i
Interpersonal Influence within Car Buyers’ Social Networks:
Observing Consumer Assessment of Plug- in Hybrid Electric Vehicles ( PHEVs)
and the Spread of Pro- Societal Values
By
JONN AXSEN
B. B. A. ( Simon Fraser University) 2004
M. R. M. ( Simon Fraser University) 2007
DISSERTATION
Submitted in partial satisfaction of the requirements for the degree of
DOCTOR OF PHILOSOPHY
in
Transportation Technology and Policy
in the
OFFICE OF GRADUATE STUDIES
of the
UNIVERSITY OF CALIFORNIA
DAVIS
Approved:
_____________________________________
Kenneth S. Kurani
_____________________________________
Thomas S. Turrentine
_____________________________________
Daniel Sperling
Committee in Charge
2010
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Abstract
Consumer purchase behavior is central to the successful deployment of alternative- fuel
passenger vehicles, which includes non- rational processes such as social influence. This
dissertation explores the role of social influence in vehicle purchase behavior via
observations of car buyers’ assessments of plug- in hybrid- electric vehicles ( PHEVs)—
vehicles that can use gasoline and grid electricity. Five theoretical perspectives on social
influence are used to analyze these behaviors: contagion, conformity, dissemination,
translation, and reflexivity. I designed and implemented a multi- method, exploratory
research design to engage households in semi- directed interviews, online surveys, a
social- network mapping exercise and a diary of social episodes. Participants included 10
“ primary” households ( 18 individuals) that drive a PHEV for a multi- week trial in the
Sacramento, California region, and 22 “ secondary” individuals that primary households
recruit from their social networks.
The analysis explores three questions: i) whether or not social interactions influence
vehicle assessment and purchase behavior, ii) how such social influence occurs, and ii)
under what conditions pro- societal motivations might develop. First, I find that social
interactions do have substantial influence over the majority of participants’ assessments.
Second, contagion and similar theoretical perspectives over- simplify processes of social
influence, while translation and reflexivity better provide the language and theoretical
depth required to integrate the observed perceptions and social processes with concepts of
self- identity. Third, car buyers that are typically motivated by the private benefits of
vehicles may be amenable to developing new, pro- societal interpretations of PHEVs
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when they: i) are in a transitional ( liminal) state in their lifestyle practices, ii) can quickly
form a basic functional understanding of PHEV technology, and iii) find supportive pro-societal
values within their social network.
A theoretical contribution of this dissertation is an integration of theoretical perspectives
with my empirical observations to create a framework representing the role of social
influence in purchase of pro- societal goods— what I call the Reflexive Layers of
Influence ( RLI) framework. Overall, this dissertation demonstrates that social influence is
important, as is the development and use of behaviorally realistic theoretical frameworks
to advance transportation and energy policies that rely on the widespread adoption of new
technologies.
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Executive Summary
The question of how and why consumers buy new products is central to the successful
deployment of alternatively fueled and propelled vehicles— and the adoption of
sustainable consumption practices in general. Although the rational actor model
dominates research on transportation behavior, behavioral economists, psychologists and
sociologist have long established that consumers do not typically follow “ rational”
decision processes ( e. g. Thaler and Sunstein, 2003; Tversky and Kahneman, 1974). This
dissertation explores the role of social influence ( or interpersonal influence) as one
determinant of consumer purchase behavior. The context for this study is the assessment
and adoption of plug- in hybrid electric vehicles ( PHEVs) as one incarnation of electric-drive
vehicle.
What are PHEVs and how are they new to consumers?
A PHEV is a combination of a hybrid- electric vehicle ( HEV)— which uses only
gasoline— and an electric vehicle ( EV)— which uses only electricity. A PHEV user could
power their vehicle with electricity from the electrical power grid and/ or gasoline ( or
another liquid fuel). Policymakers are increasingly viewing PHEV technology as a means
to meet environmental and energy goals in transportation. From a consumer’s
perspective, PHEVs can be perceived and valued according to two dimensions ( Table E-
1). First is the functional/ symbolic dimension ( Hirschman, 1981). Functional benefits
relate to what the PHEV can physically do for the consumer, such as reducing gasoline
costs and engine noise. Symbolic benefits relate to what the PHEV can represent, such as
expressing the buyers’ environmental or nationalistic identity, or helping them to fit in
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with a certain social group. The second dimension is private/ societal ( Green, 1992),
which concerns who receives the benefit: the individual or household ( private benefits),
or the community, nation, or society at large ( societal benefits). Each individual may
value PHEVs based on different attributes within this framework, and their perceptions
will change as they are exposed to and learn more about the vehicle technology.
Table E- 1: Conceptualization of PHEV attributes ( hypothetical examples)
Functional Symbolic
Private • Save money
• Reliable
• Fun to drive ( experiential)
• Expression of self- identity
• Convey personal status to others
• Attain group membership
Societal • Reduce air pollution
• Reduce global warming
• Reduce oil use
• Inspire other consumers
• Send message to automakers,
government, oil companies
Because humans are social beings, perceptions of functional, symbolic and pro- societal
attributes as well as purchase decisions are firmly embedded in social processes. Yet only
very recently have transportation researchers begun to explore the role of social
interactions in individual transportation decisions. The dominant research approach is
based on the rational choice model of discrete choice— representing the consumer as an
actor that chooses among available alternatives to maximize their individual utility.
However, in reality consumers do not typically act in isolation, nor do they typically
follow rational, deliberative decision processes when they purchase a vehicle.
Research questions
This dissertation explores the role of interpersonal influence in the formation and
stabilization of such perceptions, considering three main research questions:
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1. Does interpersonal influence play a significant role in the adoption of electric
drive vehicles?
2. If so, how can we characterize the interpersonal processes that impact consumer
perceptions of functional, symbolic and pro- societal attributes?
3. Under what conditions might households adopt electric drive vehicles and the
pro- societal car? ( And how might policy create those social conditions?)
Methods: Mapping, stimulating and observing social Networks
To collect empirical data on social influence, I designed and implemented a multi-method,
qualitative research project. Working with a PHEV demonstration project
conducted in the Sacramento, California region, I utilized a subset of 10 participating
households. Research instruments included a series of semi- structured interviews, a two-part
online survey, a social network construction exercise, a social episode diary and an
influence ranking exercise. An approximate timeline of the research design is depicted in
Figure E- 1. In the first interview, each of the 10 “ primary” households were instructed to
construct a map of their social network, then to recruit several of their friends or family
( or other alters) to take part as “ secondary” participants. Next, the primary household
substituted a PHEV for their current vehicle for a multi- week trial. They recorded any
social interactions that pertained to the PHEV in a social episode diary, and described
these interactions in subsequent interviews. In the final interview, the primary household
assessed the PHEV technology, then ranked how influential different experiences were in
their PHEV assessment. In total, 10 primary households ( 18 individuals) and 22
secondary participants took part in the project. This “ sample” includes participants with a
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wide variety of demographic, socioeconomic, and attitudinal characteristics—
approximating the distributions of larger, representative samples of car buyers used in
several previous studies.
Figure E- 1: Timeline of research design ( approximate)
Initial
invitation
“ Network”
Interview (# 1)
Survey
( Part 1)
“ Drop- off”
Interview (# 2)
PHEV Trial
Social Episode Diary
“ Midterm”
Interview( s)
(# 3, # 4)
“ Closing”
Survey Interview
( Part 2)
PRIMARY
HOUSEHOLD
SECONDARY
PARTICIPANT
Invitation
By Primary Survey
( Part 1)
Vehicle
Driving Diary
Survey
( Part 2)
Phone
Interview
Timeline
( Weeks) 0 1 2 3 4 5 6
Invites Social Interaction Social Interaction
PHEV
Assess-ment
Results
Figure E- 2 illustrates the types of results flowing from this dissertation using the social
network of one primary household, Billy Woods, as well as the social interactions
observed within his network during his PHEV trial. Billy identified 44 people as very
close or somewhat close, i. e. within the first four circles of his network ( the y- axis in
Figure E- 2). Billy mentioned or discussed the PHEV with 11 of these alters during his
trial ( A- K), eight casual acquaintances ( I- Q), and one stranger ( R). Recruited secondary
participants are identified with a thicker circle ( F, J, K and R). The darker shading in a
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circle indicates that Billy rated interactions with that individual to have had relatively
higher influence on his assessment of PHEV technology. The number of identified alters
and social interactions differed across the ten primary households.
Figure E- 2: Billy Woods’ sociogram
1st Circle
2nd Circle
3rd Circle
4th Circle
Casual
Acquaint.
Stranger
Family
Out- of- State
Friends
Former
In- Laws
Longt ime
Friends
Golf Buddies
and Friends
Coworkers
Girlfriend and
Her Daughter
Social Proximity to Billy
Didn’t discuss PHEV w/ Billy
Lower influence interaction
Mod influence interaction
Higher influence interaction
Interviewed secondary
Somewhat close tie
Very close tie
X
X
X
X
Billy Woods
From each participating household’s interview and survey data I construct a narrative of
their PHEV trial. Box E- 1 is an example of an abbreviation of the narrative elicited from
Billy Woods. The narrative follows a chronological, causal flow of experiences and
events. It begins with the participant’s background information and expectations of the
study. Next is the household’s PHEV trial experience, including driving and recharging
the vehicle, as well as talking to various alters. Finally, the household concludes with
their overall assessment of the PHEV technology, which may or may not differ from their
initial expectations. I analyze each narrative to explore the five perspectives of social
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influence gleaned from previous literature, and to further look for patterns that help
explain why some households develop pro- societal values, while others don’t. Results
suggest answers for each of the three research questions I set out to explore.
Box E- 1: Billy Woods tries on a new lifestyle
The beginning: A bachelor lifestyle
Billy is a single man in his mid- forties living alone in a detached home in Sacramento. After an
“ amicable” divorce a couple of years ago, Billy’s bachelor lifestyle is suggested by his décor: a
surfboard in the backyard; a dining room dominated by a large putting green, a counter-mounted
wine opener, and liquor dispenser; and a living room with a large flat- screen TV. Billy
describes himself as a social guy who will typically “ make friends pretty easy,” and he
identified 44 alters in his social network ( Figure E- 3). He completed degrees in civil
engineering and business, and he currently earns a six figure income as a public relations
person at a computer company. He owns a 1995 Lexus ES 300 which he bought used from
his sister and currently uses for commuting— although he often works from home— as well as
an older pickup truck he occasionally uses on weekends, and a small Harley Davidson
motorcycle.
Prior to participating in this study, Billy had little familiarity with his current energy
expenditures, including gas and electricity use. He also had no previous experience with
“ electric- drive,” not even a Prius, and didn’t initially understand the differences between an
HEV, PHEV and EV. He expected the PHEV itself to be “ sluggish, not to perform like a regular
combustion engine.” Billy also anticipated that he would talk to many people about the
PHEV— when researching something new, he would typically “ toss it to other people to see
what their thoughts are, if it is worthwhile… some suggestions.”
The trial: Showing off, exploring and polling others
Throughout his trial, Billy learned about the PHEV through experiences with the technology
itself, as well as through some of his 18 social interactions. At first, Billy would initiate
conversations to “ show off” the vehicle; he called his sister ( B) and Mother ( A) to tell them
about the study but discovered his mother had little concept of hybrid vehicles, and his sister
was unimpressed that the car was “ just a Prius.” During these and other “ small talk”
conversations, e. g. with co- workers ( L- O), his bartender ( P), his barber ( Q), Billy engaged in
a general “ intro” pattern, briefly describing the study, how the car was special, and then
answering some basic questions.
Billy also had more meaningful experiences that helped him to learn about the technology. He
faithfully substituted the PHEV for his Lexus, commuting to work most weekdays, running
errands, and driving to golf on weekends. He quickly concluded that driving the PHEV was
“ really no different from any other car,” except for perhaps being quieter. When it came to
performance, Billy “ was not disappointed at all” and was impressed with the vehicle’s “ pick- up”
and acceleration capabilities: “ it had some power, it could get to speed… just like any other
car.” However, he noted some drawbacks, such as when his golfing buddy, Albert ( D) pointed
out that at higher speeds, “ you can actually hear the engine almost racing… like it was trying
to power up… it left some kind of worry.”
Billy talked frequently about the PHEV with his coworker and friend, June ( J), who helped him
experiment with many of the Prius’ features, such as the energy monitor. Billy also spent
some time playing with the monitor on his own, and would often watch it to judge the PHEV’s
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state of charge and to see when the vehicle was using gasoline or electricity
Billy plugged in the PHEV as often as he could. He recharged at home almost “ every
night… just plug it in and go to bed.” Although he didn’t initially know he could recharge at
work, June ( J) encouraged him to look more aggressively— he then discovered a special spot
reserved for EV recharging and moved his car there after lunch that day. From then on, he
plugged in nearly every day at work. Billy also plugged in at his girlfriend Pat’s ( F) house on
two occasions.
Throughout his trial, Billy highlighted the PHEV’s potential to save money. However, he never
made “ an entire assessment.” He tried to calculate savings based on the cost of filling the
tank, but ultimately he couldn’t quantify fuel savings beyond the general notion that “ it uses a
lot less gas.” Billy was more comfortable framing fuel savings according to vehicle’s range
with a full tank, as with his story of a trip to Monterey with Pat ( F):
“ just before I went to Monterey, ( the tank) was pretty much empty… I thought I could make
the entire trip… didn’t quite make it…[ but] it was in excess of 400 miles… that was really
cool…[ it shows] you get more bang for the buck… that was neat to see, really cool.”
While Billy primarily focused on the “ bang for your buck” aspect of fuel saving, he also
highlighted a specific conversation with several of his “ opinionated” co- workers ( M, N, O) as
particularly influential. After seeing a question on the online survey, Billy had become
interested in societal motives. He then took this question to his coworkers:
“[ I asked them] why would you buy a hybrid? Mainly to protect the environment, or from a
consumer standpoint?… and all of them said if it costs less I’ll buy it, basically it’s all
consumer… and that’s what I answered on the survey… to buy it just to protect the
environment is probably not something I’d do at this time… I’ll look at buying something
that would have less of an impact on my pocket book more than anything else.”
Near the end of his trial, Billy plugged the PHEV into the same circuit that was being used by
another coworker, Harry ( R), that built and drove his own EV ( converted from an old
Volkswagen Rabbit), which led to a phone conversation between them [ see Harry’s
perspective in Box 3]. Billy was impressed that Harry’s EV had a retractable cord, which made
him think that manually coiling the PHEV extension cord was a bit “ hokey” and vulnerable to
theft. Billy was most excited about Harry’s expertise regarding alternative fuel technology:
“[ Harry was] very influential because he was really encouraging about this
technology… and he’s the one that pointed out the hydrogen technology… he just opened
up some questions…( that) I couldn’t answer…( I’m) already thinking that electricity might
already be outdated… if they’re exploring other technologies.”
PHEV assessment: Saving money at 50 mpg
By the end of his PHEV trial, Billy was impressed with the PHEV. His emphasis was on getting
“ more miles per gallon, from a cost savings standpoint.” While Billy feels that achieving 100
MPG would be “ cool,” he was happy enough with around 50 MPG, which is “ just ideal
because I’m comparing it to what my motorcycle gets, so if I can get at least that much that
would be great.” For Billy “ the exciting part of it is the electrical part.”
However, Billy clearly expressed reservations about what kind of plug- in vehicle he would
want to own, outlining several inclinations that ultimately favored a truck design. He wants a
vehicle that is stylish like a truck: as a “ single guy… I’m not going to drive midtown in
something that looks like an egg.” He also values the practicality, versatility and safety he
associates with trucks. Further, Billy expresses uncertainty as to whether PHEVs represent
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Result # 1: Social influence does matter. The first question implicitly asks if social
influence is worth researching in the first place. Results clearly indicate that yes, in the
context of this study, social influence does matter. Of the 10 primary households, nine
identify at least one social interaction as being at least moderately influential over their
assessment of the PHEV— and the one remaining household explained that social
influence had occurred during their previous vehicle purchases ( just not in the context of
their PHEV assessment). Thus, all households yield evidence that social interactions play
an important role in vehicle assessment. Further investigation of the observed social
interactions, e. g. via logistic regression analysis, suggest that interactions between the
primary household and a given alter tend to be rated as more influential when: pro-societal
aspects of the PHEV are discussed, the alter has more functional understanding
of electric- drive technology than the primary participant, and the primary and alter are
socially close ( in a general sense).
Result # 2: Social influence is driven by diffusion, translation and reflexivity. In
Chapter 2 I identify five general research perspectives on social influence and consumer
behavior ( Table E- 2). Contagion emphasizes the importance of the unidirectional flow of
information, as in diffusion of innovations ( DOI) ( e. g. Rogers, 2003). Conformity
accounts for how an individual is influenced by their perceptions of what others around
the future of technology, particularly after Harry ( R) mentioned the potential for hydrogen. Billy
likens vehicles to computers, describing alternative- fuel advancements as a progression of
upgrades to conventional vehicles: “ people are with hybrids today…[ now] potentially a plug-in…
and then, all of a sudden maybe that hydrogen technology will outlast what you
[ researchers] are offering here.”
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them are doing or expecting ( e. g. Granovetter, 1978). Dissemination describes how
groups of resourceful, pro- societal individuals can coordinate to intentionally diffuse
positive information about a pro- societal product or technology— known as a critical
mass ( e. g. Oliver, et al., 1985). Translation represents how social groups can negotiate
different interpretations of a new technology, eventually reaching a state of agreement
and influencing the development of the technology in the process ( e. g. Law and Hassard,
1999; Pinch and Bijker, 1984). Lastly, reflexivity describes how individuals work to
arrange their various lifestyle practices, such as the purchase and operation of a vehicle,
into a meaningful trajectory that effectively communicates their self- concept, which is
itself mediated and negotiated through of such practices ( Giddens, 1991).
Table E- 2: Comparing alternative perspectives on interpersonal influence
and adoption behavior
Contagion Conformity Dissemination Translation Reflexivity
1. What is the
innovation?
( static/ dynamic)
Innovation
( static)
Behavior
( static)
Collective good
( static)
Artifact
( dynamic)
Lifestyle practice
( highly dynamic)
2. System
boundaries?
( static/ dynamic)
Social system of
potential
adopters, ( static)
Relevant social
group
( static)
Social system,
critical mass
( static)
Relevant social
groups:
( dynamic)
Social system,
lifestyle sectors,
( highly dynamic)
3. Who adopts
first?
Innovators and
early adopters
Instigators Organizers Social groups who
perceive artifact as
a solution
Those finding
practice
compatible with
self concept
Why? Higher
“ innovativeness”
Low threshold High interest
and resources
Interpretation of
solution
Search for self-identity
4. Who adopts
later?
Imitators, early
to late majority,
laggards
Conservatives,
due to higher
thresholds,
Non- organizers Social groups that
later reinterpret
problems/ solutions
Same as above
Why? Lower
“ innovativeness”
High threshold Efforts of
organizers
Interpretive
closure
Search for self-identity
5. What drives
adoption?
Contagion:
interpersonal
communication
of information
Conformity:
motivation to
mimic, learn
from, or join
others
Dissemination:
willingness of
organizers to
achieve social
good
Interpretation:
perceived ability
of innovation to
solve a problem
Reflexivity:
creating and
sustaining self-identity
Best applied to
what types of
attributes?
Private-functional
Symbolic
( private and
societal)
Societal
( functional
and symbolic)
All All
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Of the five perspectives I find that contagion, conformity, and dissemination provide
useful concepts for particular processes, but translation and reflexivity better provide the
language and theoretical depth required to integrate the various motives and perceptions
observed among participating social networks. Further, contagion, conformity, and
dissemination hold important variables constant: contagion assumes unidirectional flow
of information between groups statically defined on “ innovativeness”; conformity only
describes the current pressures and norms of a given social system; and dissemination
focuses on a core group of pro- societal lifestyle practitioners. In contrast, translation and
reflexivity acknowledge the ongoing negotiations and development of interpretations,
values, and lifestyle practices associated with evaluating an innovation ( as seen with
Billy Woods’ consideration of pro- societal values in Box E- 1). However, the notion of
diffusion ( categorized within the contagion perspective) is useful for describing and
exploring the flow of simple, functional information relating to the PHEV— which proves
to be an important foundational process in PHEV assessment. Thus, I conclude that
processes of social influence are best characterized using concepts from three
complementary perspectives: diffusion, translation, and reflexivity.
Result # 3: Pro- societal values can be developed. I observe that four of the 10 primary
household used their PHEV trial actively experiment with pro- societal values (“ pro-societal
explorers” in Table E- 3). Two of these households ( Woods and the Rancheros)
concluded their PHEV trial with primarily private values ( where they started), while the
other two ( Potter and the Forts) concluded with relatively stable pro- societal values ( a
significant shift from where they started). Through narrative analysis, I identify
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conditions that explain why some households consider pro- societal values, and of those
that do, why some commit to pro- societal values while others do not. I identify three
conditions— in the context of this PHEV trial, it appears that each condition is necessary
( but not sufficient) for an initially privately- motivated household to shift towards pro-societal
values and lifestyle practices.
Table E- 3: Three patterns of interpersonal influence in social networks
Primary HH
( example)
1) Liminality 2) Functional
understanding:
easily learn
about PHEV?
3) Support
from social
network?
E- drive novices, “ private lifestyle”
The Noels: Low No No
The Petrovs: Mod No No
Betty Earhart: Mod Yes No
The Stashes: Low Yes No
Melissa Stashe: High No No
E- drive novices, “ pro- societal explorers”
Billy Woods: High Yes No
The Rancheros: Mod Yes No
Ethel Potter High Yes Yes
The Forts: High Yes Yes
E- drive enthusiasts, “ pro- societal lifestyle”
The McAdams: Low Yes Yes
The Rhodes: Low Yes Yes
Lifestyle liminality ( condition 1). If the household is not already engaged in a pro- societal
lifestyle, their lifestyle must be liminal enough to permit them to consider alternatives to
their current private lifestyle— that is, they must be in a relatively flexible, open- minded
state regarding their self- identity. Liminality can be a temporary state of transition, as
with a shock to the household such as a divorce, e. g. Billy Woods, or sustained, such as
when a household’s children grow up and move out, as the disposable income increases,
or when the individual’s self- concept is oriented towards flexibility and openness.
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Functional understanding ( condition 2): The second condition is a basic functional
understanding of the PHEV technology. The household does not need prior experience or
familiarity with electric- drive technology, nor do they need to be electric- drive experts or
enthusiasts. However, an individual or household must at least understand what the
PHEV does, i. e. how its function differs from a conventional vehicle, before they can
form a stable assessment of who it is good for, that is, before they can frame its benefits
according to private versus societal impacts. Having a technical background appears to
facilitate quicker learning of these functional aspects.
Social support ( condition 3): The third condition is the demonstrated support of pro-societal
values within the household’s social network. Among the households that
explored pro- societal values, the presence or absence of such support is associated with
their final interpretation of the PHEV. The two households concluding with private
interpretations described a lack of pro- societal support in most key areas of their social
network. For example, Billy Woods polled his coworkers about their motives to buy an
HEV, and then sided with their financial ( private) response. In contrast, the two
households that concluded with pro- societal interpretations of the PHEV perceived social
support for pro- societal values among alters they considered to be particularly influential.
Reflexive layers of influence ( RLI) and policy implications
As a final stage to this dissertation I propose an integrative perspective on the role of
interpersonal influence in adoption behavior, which I call reflexive layers of influence
( RLI). This perspective represents four layers that lay beneath the “ surface” of the
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observed vehicle purchase ( Figure E- 3). Building up from the bottom, these layers are:
functional awareness, assessment of the technology ( private and/ or societal), self-concept,
and behavioral outcome, e. g. purchase. The individual, household or social
group in question is identified as an actor, while the technology in question is a socially-defined
artifact.
Figure E- 3: The basic RLI framework
Diffusion
Translation
Reflexivity
Who
am I?
Benefits
to me/
others?
Artifact
assessment
Self-concept
Layers: Actor
What is it?
Awareness
information
Adopt or
not.
Behavioral
outcome Processes
of influence:
Social
group
Social
group
Contextual
factors
Social influence follows different processes at different layers. Social influence impacts
lower layers through the diffusion of simple information, such as awareness of the artifact
in question. Social influence impacts the private and societal assessment layers through
translation, where the actor interprets benefits of the artifact that relate to their interests
and lifestyle practices. These assessments are reflexively linked to the actor’s self-concept,
which can both serve to frame the actor’s assessment, and be reinforced or
xvii
altered according to their assessment. This self- concept is reflexively linked to the
apparent lifestyle practices of other actors, as well as the actor’s purchase intention and
eventual adoption behavior. All RLI layers are constrained by contextual factors,
including the actor’s life stage, disposable income, and need for a new artifact, as well as
market availability, price, marketing efforts and government support. When the actor’s
assessment of the artifact aligns with their lifestyle trajectory and favorable contextual
factors, they are more likely to adopt the artifact. The RLI perspective represents all of
these layers as dynamic and subject to processes of social influence.
Policy implications
The dominant perspective on transportation behavior, the rational choice model, suggests
only two levers for policymakers to influence consumer behavior: changing price ( via
financial incentives or disincentives) and providing functional information about the
product or behavior. In contrast, this dissertation attempts to move beyond simplistic
behavioral models, exploring a multitude of complex processes that influence human
behavior. Social influence can be a very powerful lever: households can alter their values
under certain conditions. Careful consideration of how different policies and types of
information can influence the different RLI layers can help policymakers to better design
policy, predict its effects, and measure its impacts ( Thaler and Sunstein, 2003). In
particular, policymakers might consider the differences between the processes of
diffusion, translation and reflexivity.
xviii
The effects of almost any policy action can be considered using RLI ( Figure E- 4). A
publicity campaign can attempt to intentionally diffuse, or disseminate, information about
PHEVs in efforts to achieve societal goals, such as awareness of the technology and
functional information about what it does. Policymakers might also disseminate this
information through labeling standards, or energy information websites. Successful
policy- driven diffusion may help to establish the awareness and functional understanding
layers that are necessary for an actor to further assess the technology. However, diffusion
alone tends not to significantly impact the individual’s assessment, self- concept, or
adoption. Translation describes a more sophisticated form of social influence where the
actor develops a more refined and stable understanding of the PHEV, how it might
benefit them personally, if it might benefit society, and ( through reflexivity) if they
should care if it benefits society. This study suggests that translation is more likely to
occur at an interpersonal level, that is, through person- to- person interaction rather than
from mass media sources, though it can also occur indirectly through other means.
Product labeling serves as one type of translation— where policymakers frame the PHEV
according to particular benefits, such as cost savings ( a private benefit) or GHG
emissions ( a societal benefit). Other policies may also be indirectly ( or unintentionally)
translated by actors. While a subsidy directly affects the price of a PHEV ( a contextual
factor in RLI), it may also help diffuse awareness about the technology, and also may be
translated through considerations of why the subsidy is being offered, e. g. PHEVs are
good for society, PHEVs are bad technologies that need government help, or the
government is wasting tax dollars. Further, a government mandate, such as the Zero-
xix
Emissions Vehicle ( ZEV) mandate, can also contribute to the popular debate about what
kind of vehicles consumers should desire, and whether they should emphasize private or
societal benefits. In short, policymakers need to consider the variety of impacts of a given
policy, including the differing processes of social influence, and RLI provides a useful
framework to do so.
Figure E- 4: Policy levers for social influence
Change context
Diffusion
Translation
Reflexivity
Functional
information
Private
assessment
Societal
assessment
Self-concept
Behavioral
intention
Layers:
Awareness
information
Behavioral
outcome
Contextual
factors
Legend:
What does
it do?
Do I
want it?
Who am
I?
Benefits
to others?
Car Buyer
Benefits
to me?
What is
it?
Adopt or
not.
 price
 availability
Policy
Subsidy
Mandate
GHG
labeling
Energy
labeling
Publicity
campaign
xx
Acknowledgements
The inquiries that drove the bulk of this dissertation were inspired by the continuing
behavioral work of Drs. Ken Kurani and Tom Turrentine. In particular, Ken Kurani
played a very integral and helpful role as advisor and guide. He encouraged me to pursue
my research interests, and frequently and reliably set aside time to provide intellectual
and emotional support in the design, implementation and analysis of this dissertation.
Still, any errors in this document are my own responsibility.
I also thank the other staff and students of the Plug- in Hybrid Vehicle Research Center
who helped with the development of this project, including Dr. Tom Turrentine, Nicolette
Caperello, Tai Sillwater, Jamie Davies, Kevin Nesbitt and Marilyn Kempster.
Special thanks for my wife, Wendy, for the continued love and support.
xxi
Table of Contents
Abstract ............................................................................................................................... ii
Executive Summary........................................................................................................... iv
Acknowledgements........................................................................................................... xx
Table of Contents............................................................................................................. xxi
List of Abbreviations ..................................................................................................... xxiv
1 Context: The Market for Plug- in Hybrid Vehicles .......................................................... 1
1.1 What is electric drive and why is it important? ........................................................ 1
1.2 Understanding PHEV technology............................................................................. 5
1.3 Anticipating the early market for PHEVs ............................................................... 12
1.4 How might consumers value PHEVs?.................................................................... 18
1.4.1 How is a PHEV an innovation? ................................................................ 18
1.4.2 The functional/ symbolic dimension: What does it do and represent? ...... 20
1.4.3 The private/ societal dimension: Who is it good for? ................................ 22
1.4.4 Attribute dynamics: How might perceptions change? .............................. 23
1.5 Why focus on the role of interpersonal influence? ................................................. 25
1.6 Summary and Scope of This Dissertation............................................................... 27
2 Consumer Behavior and Interpersonal Influence .......................................................... 29
2.1 Models of sustainable consumption........................................................................ 30
2.2 Applications to vehicle purchase behavior ............................................................. 36
2.3 Perspectives of interpersonal influence and adoption............................................. 38
2.3.1 Contagion: Interpersonal communication................................................. 41
Diffusion of innovations ( DOI) ............................................................................ 42
Social networks analysis ....................................................................................... 51
2.3.2 Conformity: Thresholds, social learning and social norms ...................... 55
2.3.3 Dissemination: Collective action and critical mass .................................. 60
2.3.4 Translation: Social construction and interpretation .................................. 65
Social construction of technology ( SCOT)........................................................... 65
Actor- network theory ( ANT) ................................................................................ 71
2.3.5 Reflexivity: Modernity and the project of the self.................................... 76
2.4 Conclusions: Towards an integrated perspective?.................................................. 81
3 Methods: Mapping, Stimulating and Observing Social Networks ................................ 85
3.1 Why follow a qualitative research approach?......................................................... 87
3.1.1 Comparing quantitative and qualitative approaches ................................. 87
3.1.2 Vehicle purchase behavior and the qualitative approach.......................... 90
3.1.3 Social influence research and the qualitative approach ............................ 93
3.2 Study context: The UC Davis PHEV demonstration project.................................. 97
3.3 Selecting participants and their personal networks............................................... 100
3.4 Overview of research design................................................................................. 103
3.4.1 Stage 1: Contact primary household and elicit personal network........... 104
3.4.2 Stage 2: Collect baseline information from secondary participants ....... 106
3.4.3 Stage 3: Stimulate personal network with PHEV trial............................ 107
3.4.4 Stage 4: Network questionnaire and selected interviews........................ 108
3.5 Research instruments ............................................................................................ 108
xxii
3.5.1 On- line PHEV questionnaire .................................................................. 109
Primary households............................................................................................. 109
Secondary participants ........................................................................................ 113
3.5.2 Constructing personal social networks ( sociograms) ............................. 115
3.5.3 Secondary participant invitations............................................................ 121
3.5.4 The social episode diary.......................................................................... 122
3.5.5 Ranking influence of experiences........................................................... 124
3.5.6 Semi- structured interviews ..................................................................... 127
3.6 Data analysis ......................................................................................................... 134
3.7 Some limitations ................................................................................................... 136
4 Empirical Results: Does Social Influence Matter? ...................................................... 140
4.1 What does the sample look like? .......................................................................... 140
4.2 Mapping social networks ...................................................................................... 150
4.3 Do social interactions matter?............................................................................... 156
4.4 Under what conditions do social interactions matter? .......................................... 159
4.5 Discussion of empirical findings .......................................................................... 166
5 Applying Five Perspectives on Interpersonal Influence .............................................. 171
5.1 Household stories: Three patterns of social influence .......................................... 171
5.1.1 E- drive novices engaged in private lifestyle: The Noels ........................ 173
5.1.2 E- drive novices exploring pro- societal lifestyle: Billy Woods............... 174
5.1.3 E- drive enthusiasts engaged in pro- societal lifestyle: The McAdams.... 175
5.2 Characterizing patterns of social influence........................................................... 176
5.2.1 Contagion................................................................................................ 177
5.2.2 Conformity.............................................................................................. 179
5.2.3 Dissemination ......................................................................................... 180
5.2.4 Translation .............................................................................................. 181
5.2.5 Reflexivity............................................................................................... 183
5.3 Discussion............................................................................................................. 188
6 The Spread of Pro- Societal Values: Narrative Analysis.............................................. 190
6.1 Social networks that emphasize private values..................................................... 193
6.2 Social networks that emphasize pro- societal values............................................. 196
6.3 Narrative accounts of social networks exploring pro- societal values................... 197
6.3.1 Billy Woods: Trying on a new lifestyle.................................................. 198
The beginning: A bachelor lifestyle.................................................................... 198
The trial: Showing off, exploring and polling others.......................................... 200
PHEV assessment: Saving money at 50 mpg ..................................................... 206
Why did Billy Woods conclude with private interpretations?............................ 207
6.3.2 The Rancheros: Recharging versus family safety................................... 208
The beginning: Family priorities and energy concerns....................................... 208
The trial: Fitting a PHEV into a hectic lifestyle ................................................. 211
PHEV assessment: Fuel economy, family- sized, then environment .................. 216
Why did the Rancheros conclude with private interpretations? ......................... 217
6.3.3 Ethel Potter: Embracing societal interests .............................................. 218
The beginning: Wanting a more “ ecological friendly” car ................................. 218
The trial: A quick convert ................................................................................... 220
PHEV assessment: Towards a solar car.............................................................. 225
xxiii
Why did Ethel conclude with pro- societal interpretations?................................ 227
6.3.4 The Forts: Hummer to hybrid ................................................................. 228
The beginning: Mass always wins ...................................................................... 228
The trial: Big surprise in a small car ................................................................... 230
PHEV assessment: Payback and the environment.............................................. 236
Why do the Forts conclude with pro- societal interpretations? ........................... 237
6.4 Discussion: Looking across narratives.................................................................. 239
7 An integrated perspective: Reflexive layers of influence ( RLI) .................................. 246
7.1 Revisiting the five research perspectives on interpersonal influence ................... 247
7.2 An integrative perspective: Reflexive layers of influence ( RLI).......................... 252
7.2.1 The innovation as a dynamic, socially- defined artifact .......................... 253
7.2.2 System boundaries: Dynamics in the relevant social system.................. 254
7.2.3 The timing of adoption: Aligning context and actor interes ................... 256
7.2.4 Driving adoption: Layers of social influence.......................................... 262
7.3 Applying the RLI framework................................................................................ 271
7.4 Generating hypotheses from the RLI framework ................................................. 279
7.5 Assessing the RLI framework............................................................................... 280
8 Conclusions.................................................................................................................. 282
8.1 Some research answers ......................................................................................... 282
8.1.1 # 1: Social influence does matter ............................................................. 282
8.1.2 # 2: Social influence is driven by diffusion, translation and reflexivity.. 283
8.1.3 # 3: Pro- societal values can be developed, subject to three conditions ... 285
8.1.4 Reflexive layers of influence ( RLI): An integrated perspective............. 287
8.2 Policy implications of RLI.................................................................................... 288
8.3 Assessing qualitative and quantitative research methods ..................................... 295
8.4 Directions for future research ............................................................................... 298
8.4.1 Ethnographic focus groups: Direct observation of social influence ....... 298
8.4.2 Large- scale online survey ....................................................................... 299
8.4.3 Measuring pro- societal values as lifestyle practices............................... 300
8.4.4 Mapping symbolism................................................................................ 302
8.4.5 Constructing life and vehicle ownership trajectory ................................ 303
8.4.6 Observing total network effects .............................................................. 304
8.4.7 Observing actual vehicle purchase behavior........................................... 305
9 References.................................................................................................................... 307
Appendix A: First interview and personal network construction ( outline) .................... 319
Appendix B: PHEV survey part 1 ( online questionnaire) .............................................. 325
Appendix C: Pre- Interview Questionnaire...................................................................... 328
Appendix D: Recruitment instructions ........................................................................... 331
Appendix E: Recruitment email...................................................................................... 332
Appendix F: Social Episode Diary ................................................................................. 334
Appendix G: Plug- in Hybrid Vehicle Guide .................................................................. 337
Appendix H: PHEV survey part 2 ( online questionnaire) .............................................. 345
Appendix I: Closing interview questionnaire ( outline) .................................................. 350
Appendix J: Experience Ranking Exercise..................................................................... 353
Appendix K: Additional Survey Questions for Secondary Participants ......................... 355
Appendix L: Phone Interview for Secondary Participants ............................................. 359
xxiv
List of Abbreviations
AE All- electric
ANT Actor- network Theory
B Blended
CARB California Air Resources Board
CD Charge- depleting
CS Charge- sustaining
CV Conventional vehicle
DOI Diffusion of innovations
EV Electric vehicle
GHG Greenhouse- Gas Emissions
GM General Motors
HEV Hybrid- electric vehicle
ICE Internal combustion engine
Li- ion Lithium- ion
NiMH Nickel- metal hydride
PHEV Plug- in hybrid electric vehicle
RFI Reflexive layers of influence
SCOT Social construction of technology
SOC State of charge
ZEV Zero- Emissions Vehicle
1
1 Context: The Market for Plug- in Hybrid Vehicles
The question of how and why consumers buy new products is central to the successful
deployment of alternatively fueled and propelled vehicles— and the adoption of
sustainable consumption practices in general. Although the rational actor model
dominates research on transportation behavior, behavioral economists, psychologists and
sociologist have long established that consumers do not typically follow “ rational”
decision processes ( e. g. Thaler and Sunstein, 2003; Tversky and Kahneman, 1974). This
dissertation explores one potential determinant of consumer purchase behavior: social
influence ( or interpersonal influence). This first chapter sets the context for the particular
type of sustainable consumption under study: the adoption of plug- in hybrid- electric
vehicles as one incarnation of electric- drive vehicle. Later chapters delve into theories of
consumer behavior and the details of the present research.
1.1 What is electric drive and why is it important?
Spurred by petroleum supply and price disruptions, air pollution policy, and climate
change policy, much effort and many resources have been devoted to the development of
electric drive vehicles over the past three decades. The oil crisis of 1973- 4 lead to
substantial government funding of research on alternative fuels, including the Hybrid
Electric Vehicle Act of 1976 which resulted in much of the electric vehicle technology
developments that emerged during the 1990s ( Turrentine and Kurani, 1996). Battery
electric vehicles ( EVs)— which are powered solely by an on- board energy storage system
2
and recharged from an external grid— captured renewed attention in the 1990s, stimulated
by General Motor’s development of the EV- 1 ( aka Impact) and California’s Zero-
Emissions Vehicle ( ZEV) mandate. In the late 1990s, after years of further technological
development and policy debate, policymakers were convinced by automobile
manufacturers that battery technology was insufficient to meet manufacturers’ EV design
goals. Since then, small markets have developed for EV applications with relatively
limited range and top speeds, such as neighborhood or regional EVs.
Although the ZEV mandate failed to produce commercially viable EVs in the intended
time frame, some battery technologies later proved successful in less demanding hybrid-electric
vehicle ( HEV) applications. HEVs are fueled by gasoline ( or potentially another
liquid fuel), combining a conventional internal combustion engine ( ICE) with an electric
motor and battery to improve the vehicle’s overall fuel economy. Relative to other
alternatively propelled vehicle technologies, HEVs have achieved significant commercial
success over the last decade, typified by the Toyota Prius ( see Figure 1). 1
Currently, interest has turned to what many claim is the next logical step from the HEV:
plug- in hybrid electric vehicles ( PHEVs). The PHEV combines aspects of the EV and
HEV, potentially operating like an EV for a limited distance, with the addition of an ICE
to replace or supplement the electric motor to extend range and increase power. No
commercial PHEVs are currently available in the US, but the technology is receiving
attention from automakers, regulators, electric utilities and consumer groups.
1 Declining market share in 2008 and 2009 may have more to do with economic recession than a decline in
hybrid popularity per se.
3
Figure 1: US annual HEV new market share, 1999- 2009
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Year
U. S. Light- Duty Vehicles Market Share (%)
All HEVs
Prius Only
Source: USDOE ( 2009)
In particular, policymakers are increasingly viewing PHEV technology as a means to
meet environmental and energy goals in transportation ( Service, 2009). In response to the
U. S. President’s 2006 State of the Union address, the U. S. Department of Energy has
published a working draft of a PHEV R& D Plan ( USDOE, 2007). In California, the Air
Resources Board amended the ZEV mandate in March 2008 to provide incentives for
automakers to produce and sell PHEVs ( CARB, 2008). More recently, President Obama
set a national target to have 1 million PHEVs on the road by 2015 ( Revkin, 2008), and as
of the beginning of 2009, a federal tax credit of $ 2,500 to $ 7,000 is offered for the first
250,000 PHEVs sold ( U. S. Congress, 2009).
4
Despite growing support, determining the environmental and societal impacts of PHEVs
is complex and the benefits are uncertain; it is a new technology capable of a wide
diversity of designs, driving and recharge patterns, and electricity sources. To date, many
studies have attempted to calculate potential energy and environmental impacts ( e. g.
Axsen and Kurani, 2008; Duvall, et al., 2007; Gonder, et al., 2007; Hadley and
Tsvetkova, 2008; Kang and Recker, 2009; Lemoine, et al., 2008; McCarthy and Yang,
2010; NAS, 2009; Samaras and Meisterling, 2008; Silva, et al., 2009; Sioshansi and
Denholm, 2009; Stephan and Sullivan, 2008). Each study yields different results flowing
from different assumptions about the type of PHEV in question, consumer driving
patterns and recharge behavior, the source of electricity used by the PHEVs, and the
baseline to which the PHEV should be compared, e. g. conventional vehicles or HEVs.
Research generally indicates that PHEV use could halve petroleum use ( Axsen and
Kurani, 2008; Gonder, et al., 2007) and reduce greenhouse gas emissions ( GHG) by one
third ( Samaras and Meisterling, 2008) to two thirds ( Duvall, et al., 2007) relative to
conventional vehicles. Under some conditions, PHEVs are depicted as being no more
desirable from a GHG perspective than HEVs ( e. g. Hadley and Tsvetkova, 2008; NAS,
2009; Samaras and Meisterling, 2008)— but such a comparison presumes that PHEVs
would be replacing HEVs rather than some distribution of conventional and hybrid
vehicles. Of course, all estimates of PHEV benefits stem from the uncertain assumptions
noted above and, of central importance to this dissertation, uncertain assumptions of
consumer purchase behavior. In any case, the strong potential for societal benefits
suggests that PHEVs at least warrant further exploration.
5
1.2 Understanding PHEV technology
Relative to other electric- drive and conventional gasoline vehicles, one potential
advantage of PHEVs is fuel flexibility. A user could power their vehicle with electricity
from the electrical power grid, gasoline ( or another liquid fuel), or both. To do so, a
PHEV has both an electric motor and a heat engine— usually an ICE. 2 This flexibility
also complicates vehicle designs and possible ways of using energy from two different
systems. Figure 2 depicts two simple schematics of possible PHEV architectures, that is,
the overall design of the PHEV system to supply power from two different sources. A
series drivetrain architecture powers the vehicle only by an electric motor using
electricity from a battery. The battery is charged from an electrical outlet, or by the
gasoline engine via a generator. A parallel drivetrain adds a direct connection between
the engine and the wheels, adding the potential to power the vehicle by electricity and
gasoline simultaneously and by gasoline only. These two architectures are illustrated by
the differing plans of two automakers: while Toyota is currently developing a PHEV with
a parallel architecture, i. e. a plug- in version of the Prius, General Motors is working with
a series architecture, i. e. the Chevy Volt.
In any PHEV architecture the battery plays a crucial role in storing energy from the
electrical grid and from the gasoline engine ( through a generator), as well as passing
energy back and forth with the electric motor to maximize efficiency. During braking and
coasting, an electric motor can convert— or, regenerate— some of the kinetic energy of
2 As the ICE in most conventional vehicles is fueled with gasoline ( or diesel), I will refer to gasoline and
gasoline engines without precluding the possibility of different future fuels.
6
the moving vehicle into electrical energy to be stored in the vehicle’s battery. “ Pure” EVs
only have an electric motor and only run on electricity and thus need batteries that can
store large amounts of energy and deliver high power. However, PHEVs can be designed
to emphasize energy or power requirements ( or both) of batteries.
Figure 2: Basic PHEV Drivetrain, series versus parallel design
Series
ENGINE
MOTOR
GENERATOR
ELECTRICAL
OUTLET
GASOLINE
Battery
Parallel
MOTOR
GEN.
ELECTRICAL
OUTLET
GASOLINE
Battery
ENGINE
In part, the commercial success of PHEVs depends on the development of appropriate
battery technologies. There is much uncertainty about what exact requirements a battery
must meet to produce successful PHEVs and where different battery technologies stand
in meeting such requirements. On the one hand, electric drive advocate often claim that
battery technology is sufficient to begin the commercial introduction of PHEVs
immediately ( e. g. CalCars, 2008; EPRI, 2007). On the other hand, some critics counter
that substantial technological breakthroughs are required before PHEVs should be
7
introduced to the market ( e. g. Kromer and Heywood, 2007). One battery researcher states
that commercialization prior to 2015 would present substantial business risk ( Anderman,
2008). Also, as the difference in initial PHEV architectures between automakers shows,
there is disagreement on what a PHEV is, or if the concept is flexible enough and the
market diverse enough to support multiple incarnations. For their part, policymakers are
unsure how to regulate PHEV emissions and “ fuel” use under conditions of such
technical and market uncertainty.
To help clarify issues relating to PHEV technology, here I briefly explain three
fundamental PHEV concepts. First, for any given architecture, a PHEV can operate in
one of two modes: charge sustaining ( CS) or charge depleting ( CD). Figure 3 ( adapted
from Kromer and Heywood, 2007, p31) illustrates these two modes in two different types
of operation. In both graphs, the blue line and left- hand vertical axis represent the
battery’s state of charge ( SOC), ranging from 0 percent to 100 percent, and the horizontal
axis is the distance traveled. 3 In these examples, the battery is “ fully” charged ( from an
electrical outlet) to 90 percent SOC at the beginning of the cycle. For a distance the
charged PHEV is driven in CD mode— energy stored in the battery is used to power the
vehicle, gradually depleting the battery’s SOC. Once the battery is depleted to a
minimum level, set at around 25 percent in this example, the vehicle switches to CS
mode. In CS mode the SOC is sustained by relying primarily on the gasoline engine to
drive the vehicle, using the battery and electric motor to increase the efficiency of the
3 In practice, the maximum SOC may be limited to less than 100 percent, and the minimum SOC
constrained to more than 0 percent, both to preserve battery life and improve safety. The difference
between the maximum and minimum SOC is known as the usable depth of discharge ( DOD), which varies
across battery and vehicle designs.
8
gasoline engine, as is now done in an HEV. Small cycles can be seen in the SOC during
CS mode ( as in CD mode), where the battery takes on energy from the engine driven
generator or from regenerative braking and uses the energy in the electric motor to
improve the efficiency of engine operation. The vehicle remains in CS mode until the
battery is plugged in again to recharge. The distance a fully charged PHEV can travel in
CD mode before switching to CS mode is called CD range.
A second key PHEV concept is that a vehicle can be designed for all- electric ( AE) or
blended ( B) operation in CD mode. A PHEV designed for AE operation can be driven for
the CD range using only electricity from the battery, and the engine is not used at all. The
top graph in Figure 3 illustrates an AE design. In contrast, a PHEV designed for B
operation ( the bottom graph in Figure 3) will use electricity and gasoline to power the
vehicle during the CD range— energy from the engine and the battery are “ blended”
together through the drivetrain. CS driving can be identical for both PHEV types, where
only gasoline is used to power the vehicle. Thus, if an AE and a B design are equivalent
in every way other than CD type, cumulative gasoline ( gold line) use will be higher in the
B design for any vehicle trips that include a portion of CD driving, as indicated by the
right- hand vertical axes in the figure. Also, a PHEV designed for AE driving will require
a battery capable of delivering more power than a PHEV designed for B driving because
the battery ( and motor and power electronics) must be capable of providing the full
power of the vehicle during CD mode, not just partial power.
9
Figure 3: Illustration of the discharge pattern of a PHEV battery (~ 65%
depth of discharge)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Distance
Battery State of Charge ( SOC)
Cumulative Electricity or Gasoline Use
Electricity
SOC Gasoline
Charge Depleting
( CD) mode - B
Charge Sustaining
( CS) mode
Blended ( B) CD Operation
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Distance
Battery State of Charge ( SOC)
Cumulative Electricity or Gasoline Use
Electricity
Gasoline
SOC
Charge Depleting
( CD) mode - AE
Charge Sustaining
( CS) mode
All Electric ( AE) CD Operation
Source: Adapted from Kromer and Heywood ( 2007, p31). Used with permission from authors.
Third, PHEV designs are commonly described according to CD range; the common
notation is PHEV- X, where X is distance in miles. For instance, a PHEV- 10 can be
driven 10 miles in CD mode before switching to CS mode. However, this notation does
10
not distinguish whether a PHEV in CD mode is operating all- electrically or using
blending, nor does it specify the driving conditions that would allow CD mode for the
stipulated distance. Comparisons of PHEVs, even those sharing the same PHEV- X
designation, must reconcile assumptions regarding CD operation and driving behavior.
Kurani et al. ( 2009) discuss how further confusion in PHEV notation can result from
differing concepts of PHEV- X. First, Gondor and Simpson ( 2007) argue that X should be
defined as the equivalent number of miles of petroleum displaced by electricity from the
battery. This approach makes no distinction between AE and B operation; a fully charged
PHEV- 10 could store and use enough electricity to reduce gasoline use by the amount of
gasoline required to travel 10 miles, but not necessarily during the first 10 miles. On the
other hand, the California Air Resources Board ( 2003) defines X as the total miles that
can be driven before the gasoline engine turns on for the first time, also known as AE
range ( or zero- emissions range). By this definition, a fully charged PHEV- 10 could be
driven for the first 10 miles without using any petroleum. CARB’s definition requires a
more powerful electric motor and battery to avoid engine use during CD mode, i. e.,
CARB assumes AE mode. Again, these distinctions must be clarified when discussing the
battery requirements of a particular PHEV design. In this dissertation, I identify CD
range and operation of a given design with the following notation: AE- X or B- X.
Given the wide variety of plausible PHEV designs, it is not easy to determine if battery
technology is “ ready” for PHEV applications. Research by Axsen et al. ( 2008; 2010)
describe how differing assumptions about PHEV operation, range, body type and driving
11
and recharge patterns can drastically influence the estimated technological requirements
of battery technology. Further, battery development involves a careful tradeoff between
five key attributes: energy capacity, power, cost, safety and longevity. Given the more
aggressive technology goals of the U. S. Department of Energy ( 2007), the nickel- metal
hydride ( NiMH) battery chemistries used by today’s HEVs will not likely be usable for
PHEV applications. Instead, lithium- ion ( Li- ion) chemistries will have to be developed,
given their potential for higher energy and power density. However, as detailed further
below, a recent consumer survey suggests that many potential PHEV buyers would be
interested in buying less technologically advanced designs, e. g. a B- 10, which could
feasibly be built with battery technology that has already been commercialized ( Axsen, et
al., 2010).
A list of PHEV designs promised by automakers suggests that a variety of PHEV designs
may be available for purchase within the next few years ( Table 1). For illustration of the
range of potential designs, compare the B- 20 Prius in development by Toyota with the
AE- 40 Volt planned by General Motors. Also note that most PHEV concept vehicles are
presented according to an AE range, even when their anticipated top electric speed ( and
power capabilities of the electric motor) is unlikely to cover the range of accelerations
and speeds required for the driving behavior of typical U. S. drivers. For instance, I add
the B- 20 specification in brackets to the Toyota Plug- in because although Toyota
typically describes the vehicles as AE- 12, the vehicle performs more like a B- 20 with
“ average use” ( English, 2009). Of course, this list of forthcoming PHEV models is highly
speculative, and the actual timing and specification of commercialized PHEVs may
12
change dramatically— but it is a useful illustration of the automotive industry’s present
perceptions of the future of PHEVs.
Table 1: PHEV model and concepts planned for commercialization
( presently publicly available)
Make PHEV
Model
Release
Year
Design Batt.
Capacity
Top
Electric
Speed
Price
Toyota Prius 2012 AE- 12.5 ( B- 20) ~ 5 kWh 62 mph ~$ 48k
GM Volt 2011 AE- 40 16 kWh > 70 mph ~$ 40k
Volvo V70 2012 AE- 30 12 kWh 80 mph ??
Ford Escape 2012 AE- 30 10 kWh ?? ??
Fisker Karma 2010 AE- 50 22 kWh 125 mph ~ 90k
VW Golf 2010 AE- 30 12 kWh 35 mph ??
Hyundai Blue- Will 2012 AE- 38 ?? ?? ??
Sources:
Toyota: http:// www. popularmechanics. com/ automotive/ new_ cars/ 4339705. html
GM: http:// www. popularmechanics. com/ automotive/ new_ cars/ 4338192. html
Volvo: http:// www. autotropolis. com/ autotropolis- columns/ car- tech/ volvo- announces- plans- for- phev- by- 2012. html
Ford: http:// www. greencarcongress. com/ 2009/ 02/ ford- selects- jo. html
Fisker: http:// www. autotropolis. com/ wiki/ index. php? title= 2010_ Fisker_ Karma
VW: http:// www. allcarselectric. com/ blog/ 1036439_ behind- the- wheel- of- volkswagens- golf- twindrive- phev
1.3 Anticipating the early market for PHEVs
The plausible early market for PHEVs can be conceptualized according to consumer
constraints, e. g. what proportion of car buyers currently have the ability to plug- in a
vehicle at their home, and according to consumer interests, e. g. what proportion of those
car buyers are interested in purchasing a PHEV, and if so, what kind of PHEV?
Several studies have explore consumer constraints, estimating the proportion of
households with home recharge access to be 28 percent in the U. S. ( Nesbitt, et al., 1992)
and 15 to 30 percent in California ( Williams and Kurani, 2006), while another study
assumes that 86 percent of American drivers park within 25 feet of an electrical circuit
13
( Graham, et al., 2001). Due to lack of direct data, such previous market analyses have
relied on assumptions about consumer behavior, which are typically drawn by proxy
from databases of travel patterns and housing stocks.
A study by Axsen and Kurani ( 2008; 2009) sought to reduce some of these uncertainties
for the plausible early U. S. PHEV market. Researchers designed a web- based survey
which they administered to 2,373 new vehicle buying households in what they judged to
be a fairly representative sample of such households in the U. S. The survey was
implemented in three separate pieces, requiring multiple days for households to answer
questions, conduct a review of their own driving and parking patterns, and then complete
a sequence of PHEV design exercises. Recharge potential data were collected with a
Plug- in Potential diary of driving and parking for one of the household’s vehicle. PHEV
design priority data were collected in with priority- evaluator games.
The authors conclude that just more than half the population of U. S. households that buy
new cars have the potential to recharge a vehicle at home with at least 110- volt service
( Figure 4). This proportion is one- and- a- half to three times larger than previous estimates.
( One explanation for this difference is that previous studies looked at all households, not
just new vehicle buyers.) Few respondents located non- home recharge opportunities, such
as at their workplace, friend’s and family’s homes, restaurants, etc. Recharge potential,
that is, the spatial- temporal correspondence between a parked vehicle and a 110- volt
electrical outlet, was estimated to peak between 12am and 6am when most vehicles are
14
parked at home, reaching a broad minimum from 10am to 4pm when most vehicles are
parked at work or other locations or are being driven.
Figure 4: Access to recharge spot ( 110- volt) by location and outlet distance
( all respondents, n = 2,373)
0%
10%
20%
30%
40%
50%
60%
70%
80%
Any Home Work Other's
Home
Store All
" Other"
50 ft. 25 ft. 15 ft. 10 ft.
Given the distributions of car buyer’s access to recharging and the interests in PHEV
designs, Axsen and Kurani estimate that about one third of U. S. new vehicle buying
households have both the required infrastructure and interest to purchase a vehicle with
plug- in capabilities— a sub- sample they identify as the plausible early PHEV market
respondents. Within this plausible early market, there is a wide diversity of consumer
interests in PHEV design options ( Figure 5). Starting with a base PHEV design offering 8
hour recharge times, B- 10 capability, and a 10 mpg increase in CS mode over a
conventional vehicle, the most popular upgrade category was improved CS fuel
economy. Respondents also exhibited interest in increasing vehicle range in CD mode,
% Finding an Outlet
Location Type
Higher Home
Recharge Potential:
Home recharge outlet
within 25 feet of vehicle
( 52.4% of respondents)
15
and improving CD fuel economy ( with more electricity and less gasoline to the “ blend”).
There was little evidence of inherent demand for AE- X vehicles, even following the one-day
driving diary, the tutorial on electric- drive vehicles, and PHEV design games. This
finding suggests that while AE- X designs may presently be attractive to a small subset of
consumers, including those who are already knowledgeable and experienced with electric
vehicles, at this point in time most households who buy new vehicles are more interested
in high fuel economy.
Figure 5: Attribute selection in design exercises ( plausible early market
respondents, n = 827)
0%
20%
40%
60%
80%
100%
Recharge
CD Type
CD Range
CS MPG
Recharge
CD Type
CD Range
CS MPG
Recharge
CD Type
CD Range
CS MPG
Recharge
CD Type
CD Range
CS MPG
Recharge
CD Type
CD Range
CS MPG
Recharge
CD Type
CD Range
CS MPG
Base Model
Recharge
CD Type
CD Range
CS MPG
Base Model
% Choosing Upgrade
Base Model
3rd Level Upgrade
2nd Level Upgrade
1st Level Upgrade
Game 1: Development Priority ( Points) Game 2: Purchase Design ($)
Round 1
( 1pt)
Round 2
( 2pt)
Round 3
( 4pt)
Round 4
( 6pt)
Round 5
( 8pt)
“ High”
Price
“ Low”
Price
Also, about one- third of the plausible early market respondents who constructed a PHEV
variant of their likely next new car ( that they selected rather than a conventional version
of that car) chose no upgrades above the proffered base PHEV design. Thus, there may
be substantial potential for market success with less ambitious PHEV designs, i. e. B- 10
16
vehicles, particularly with high CS fuel economy. This wide variety of PHEV design
selections supports the notion of a “ blank slate” early PHEV market, where early buyers
may have little in the way of performance expectations— that is, expectations of what a
PHEV is or should be.
Translating these consumer interests to battery requirements ( Figure 6, from Axsen, et al.,
2010) suggests that the vast majority of consumer- selected PHEV designs ( grey circles)
fall within the energy and power capabilities of an already- commercialized battery
chemistry ( NiMH), and also fall short of the PHEV technology goals ( power density and
energy density) espoused by experts from the U. S. Advanced Battery Consortium
( USABC) ( Pesaran, et al., 2007) and Massachusetts Institute of Technology ( MIT)
( Kromer and Heywood, 2007). In other words, while some expert goals for PHEV
batteries call for advanced Li- ion battery technology or better, the PHEV design interests
of the majority of plausible early market respondents in this nationwide study suggest
that the cheaper battery technology currently proven in HEV applications ( NiMH), or
something like it, could be used to meet the needs of most early PHEV buyers— if they
are given the opportunity to buy the PHEVs they say they want.
Overall, these analyses provide baseline measures of market potential— which could be
highly subject to influence. Recharge infrastructure could expand to a higher percentage
of households with changes in residential building and remodeling codes, as well as
increased employer and publicly installed vehicle recharge outlets. Desired PHEV
designs and capabilities may be even more subject to change. Survey respondents had
little pre- existing understanding of PHEVs and the elicited responses could be sensitive
17
to the PHEV information provided by researchers. As information about PHEV
technology spreads throughout social groups and the economy, along with corresponding
developments in PHEV values and meaning, interest in particular attributes could shift.
For example, AE- X designs could become more meaningful to car buyers as they gain
experience and as they participate in the process of identifying just what AE- X means to
people— particularly as battery costs decline with increased manufacturing experience.
But the baseline provided by this research does help illuminate near- term opportunities
for PHEVs, as well as questions for further research, which I now consider for this
dissertation.
Figure 6: Distribution of battery requirements for PHEV designs selected by
potential early market respondents and USABC, MIT, and EPRI
Source: Chemistry Ragone plots from Kalhammer et al. ( 2007).
Notes: For UCD Cars and Trucks, the areas of the circles are proportional to the number of respondents
who designed the PHEV from which those battery requirements flow. The circles indicating
USABC’s, MIT’s, and EPRI’s requirements are sized simply to make them perceptible.
The potential early market respondents plotted here account for 33 percent of the entire survey
sample of U. S. new car buying households.
18
1.4 How might consumers value PHEVs?
1.4.1 How is a PHEV an innovation?
While the studies noted above help depict the distribution of recharge constraints and
design interests of the plausible early PHEV market, it is also important to understand the
perceptions and motives of these potential buyers. In other words, which attributes of the
technology are perceived as important benefits by vehicle buyers? This question is
particularly challenging when focusing on a new technology, which, from a technological
perspective, is often described as an innovation. Classifying the technology as an
innovation requires further clarification about what is being replaced by the innovation, if
anything, and how “ disruptive” the innovation might be for the current market. However,
here I caution against following a purely technological perspective. Such an approach
focuses on the functional attributes of electric- drive vehicles: the drivetrain that dictates
engine performance, driving range and potential for fuel savings. These attributes would
be compared to the conventional gasoline engine drivetrain that could be replaced. The
transition required for consumers to adopt the innovation is sometimes described on a
continuum of continuity, concerning the degree of change in the physical product itself,
its performance or its price ( Ehrnberg, 1995). Robertson ( 1971) provides a commonly
cited classification: a continuous innovation involves only a slight modification to an
existing product, and a discontinuous innovation is a previously unknown product that
requires drastic behavior changes. From this perspective, the more continuous an
innovation is, the more easily it can diffuse and attain market success.
19
From this technological perspective, one might speculate that, for consumers, an HEV is
a relatively continuous innovation; there is only a slight modification to the conventional
gasoline vehicle that does not require change in consumption behavior, such as driving or
refueling. In contrast, an EV is relatively discontinuous, requiring a drastic shift in
refueling behavior— where the gas pump is completely replaced with an electrical
outlet— as well as some degree of training and adaptation in driving patterns to make use
of a presently limited refueling infrastructure. It is thus tempting to explain the different
adoption rates of each technology based on functional continuity: as a relatively
continuous innovation, the HEV has achieved significant market success; as a relatively
discontinuous innovation, the EV has not. A purely technological approach also
encourages researchers to focus on the incremental cost savings provided by electric-drive
vehicles, such as by calculating payback periods and discount rates that are
assumed to represent consumer perceptions regarding an HEV purchase.
However, a pure technological focus misses important issues, illustrated by
Adamson’s ( 2003, p772) alternative conceptualization of discontinuity as describing
“ products that, through the use of new technologies, create within the user group a
paradigm shift in beliefs, attitudes and use.” This consideration of beliefs and attitudes is
an essential addition: what matters is how any technological or functional change is
perceived by consumers. In this dissertation I do away with the notion of continuity, and
instead provide a conceptualization of which attributes may be important for consumers
considering an electric- drive vehicle— according to two dimensions in Table 2:
functional/ symbolic and private/ societal.
20
Table 2: Conceptualization of PHEV attributes ( hypothetical examples)
Functional Symbolic
Private • Save money
• Reliable
• Fun to drive ( experiential)
• Expression of self- identity
• Convey personal status to others
• Attain group membership
Societal • Reduce air pollution
• Reduce global warming
• Reduce oil use
• Inspire other consumers
• Send message to automakers,
government, oil companies
1.4.2 The functional/ symbolic dimension: What does it do and represent?
The first dimension, functional/ symbolic, is related to Hirschman’s ( 1981) categorization
of innovations based on which type of attribute is perceived as novel by consumers:
technology or symbolism. To Hirschman, technology innovations are tangible and
functional, including the new services provided by the physical nature of the innovation,
such as a fuel savings for HEVs. In contrast, symbolic innovations are intangible, where
the innovation “ communicates a different social meaning than it did previously”, such as
“ sexiness, conservatism, and prestige” ( Hirschman, 1981, p537). Hirschman ( 1981)
presents a simple classification for innovations according to these dimensions,
categorizing automobiles generally as both “ high technology” and “ high symbolism”. In
regards to adoption behavior and the diffusion ( further explained in Chapter 2) of the
technology through a social system, Hirschman ( 1981, p537) highlights the importance of
carefully considering the symbolic dimension, where symbolic innovations may “ possess
fundamentally different properties and diffuse according to fundamentally different
principles” relative to functional innovations. For an innovation scoring high on both
21
dimensions, symbolism may present a sort of “ secondary diffusion for it among those
identifying with a relevant reference group” ( p537).
Demand for motor vehicles is known to be associated with intangible, symbolic
motives— often more so than functional motives ( e. g. Steg, 2005; Steg, et al., 2001). In
describing the history of automobile use in America, Gartman ( 2004) illustrates how
intangible motives were dominant from the very introduction of automobiles in the late
19 th century. Vehicles were “ used not for practical purpose but for leisure activities and
public ostentation… the automobile quickly became defined in American culture as an
instrument of freedom and leisure, and a symbol of wealth” ( Gartman, 2004, p171).
Following the development of the automobile to the present day, Gartman ( 2004, p187)
describes the latest era of automobiles as one of “ subcultural difference,” where the
desire of consumers to distinguish themselves continues to prevail, stimulating the
emergence of new vehicle classes that demonstrate a distinct “ lifestyle choice,” such as
SUVs, minivans, and according to Gartman, HEVs.
Focusing on HEVs, Heffner et al. ( 2007) conducted dozens of household interviews of
HEV owners, finding that symbolism played an important role in every buyer’s purchase
decision. The authors classify five common symbolic meanings: “ preserve the
environment,” “ oppose war,” “ manage personal finances,” “ reduce support to oil
producers,” and “ embrace new technology.” Further, among individual households, these
broader symbols were linked to more personal meanings, such as ethics, national
independence and individuality. The authors found that the “ HEV purchases were about
22
constructing and communicating” the buyers’ self identity “ through a widely recognized
environmental symbol” ( Heffner, et al., 2007, p412). Thus, it is important to consider
both functional and symbolic perceptions of electric- drive vehicles. In Table 2, function
denotes attributes of functional or instrumental importance, including the basic services
of accessibility and mobility provided by an automobile, or the incremental fuel savings
provided by HEVs and PHEVs; the symbolic dimension includes the less tangible
attributes of the vehicle, such as the owner’s desire to express a certain value.
1.4.3 The private/ societal dimension: Who is it good for?
The second dimension in Table 2, private/ societal, provides a clear distinction between
electric- drive and ICE vehicles. Green ( 1992, p133) describes a private good as being
characterized by “ exclusive and personal consumption and individual payment; not
associated with the public welfare.” On the other hand, a public ( or pro- societal) good is
characterized by “ nonexclusive consumption and collective payment” such as “ clean air”
and “ saving endangered species.” Canzler ( 1999, p25) asserts that motor vehicles are
perceived as primarily private goods, dating back to the original “ race- travel- limousine”
vision, where increasing demand was driven by goals of luxury and prestigious racing.
However, electric- drive vehicles may present a divergence from the private good vision,
having the potential to produce pro- societal benefits, such as contributing to reductions in
air pollution, greenhouse gas emissions and foreign oil dependence. Thus, HEVs and
similar vehicles can be associated with public welfare. The addition of these societal
23
attributes leads Brown ( 2001) to classify the EV as a mixed good, that is, with aspects of
a private and societal good. I extend this classification to HEVs and PHEVs.
The possibility of significant pro- societal attributes indicates that electric drive and other
alternative propulsion vehicles may together produce a deviation from the purely private
connotation of the conventional ICE. In essence, the emergence of electric- drive vehicles
is not just an extension to the race- travel- limousine concept of a private good with
functional and symbolic attributes, but in some cases could represent a new vision of
motor vehicles I call the pro- societal car. The pro- societal car includes any vehicle
technology that potential adopters can associate with public benefits; such technologies
include hydrogen fuel cell, ethanol, and biodiesel vehicles. The word pro- societal
represents all societal benefits, including environmental benefits, but also concerns of
foreign oil dependence, or a desire to send pro- societal messages to government, oil
companies, automakers or other drivers. 4
1.4.4 Attribute dynamics: How might perceptions change?
To understand patterns of adoption and diffusion of an innovation over a particular time
frame, one must account for dynamics in consumer perceptions of relevant functional,
symbolic and societal attributes. For emerging technologies like electric- drive vehicles,
significant shifts in all four boxes of Table 2 can be expected. First, functional attributes
4 I also consciously chose the term “ pro- societal” rather than “ pro- social” for this dissertation to avoid
confusion with the other meaning of social, i. e., interpersonal. This dissertation’s primary emphasis is the
exploration of social influence and social networks in this sense of interpersonal exchange rather than non-excludability.
Throughout this dissertation, “ social” is thus reserved as a synonym for interpersonal.
24
change with advances in battery and electric drivetrain technology. For HEVs, what may
not be clear in Figure 1 is that the physical nature and variety of the “ hybrid” has changed
between 1999 and 2009; available vehicle models have increased from one to 19,
including increases in the variety of body styles, degree of hybridization, achievable fuel
economy, and range of purchase price.
Symbolic meanings are also dynamic. After teasing out several common meanings of
HEVs, Heffner et al. ( 2007, p412) suggest that “ as HEVs persist in the marketplace and
as the variety of models expands, established meanings will evolve and new meanings
will be added… new buyers may be motivated by novel meanings that were not
recognized by earlier buyers.” As will be explored in Chapter 2, within and among social
groups the creation of new symbolic meanings is a process of negotiation and
renegotiation among many parties.
Third, perceptions of pro- societal benefits can be similarly dynamic and negotiable
( Smith, 2005). Hess ( 2007) outlines an ongoing dispute over what constitutes a “ clean
bus” among U. S. cities. He demonstrates how fleet purchase decisions between
compressed natural gas and emissions- controlled diesel vary with continual shifts and
advances in technology ( including hybridization), health research on the effects of air
pollutants, emissions data, government regulation, and mobilization by activists and other
public- interest groups. Similarly, Calef and Goble ( 2007) describe the controversy over
the societal benefits of EVs during California’s ZEV mandate in the 1990s, where
industry and pro- environmental interest groups battled to influence the state’s perception
25
of the societal benefits of EVs. In another example, Calef and Goble ( 2007) illustrate how
the EV movement in France was not supported by environmental groups due to a
different priority: protesting the nuclear power plants that are used to generate electricity.
What may be defined as “ clean” at one moment or in one context is subject to change—
and not just for brand new technologies. In 2007 for example, when HEVs had been
commercially available in the U. S. market for nine years, a marketing firm released a
report stating that from a lifecycle perspective of energy use, the Toyota Prius performed
significantly worse than several SUVs, including the Hummer ( CNW, 2007). Despite the
many methodological flaws of that study, its findings were propagated in the media and
are said to have since “ distorted the debate” ( Gleick, 2007, p1), planting doubt in the
minds of some potential HEV buyers. In summary, the perceived societal attributes of
emerging technologies, like functional and symbolic attributes, are subject to change and
negotiation.
1.5 Why focus on the role of interpersonal influence?
Because humans are social beings, perceptions of functional, symbolic and pro- societal
attributes as well as purchase decisions are firmly embedded in social processes. Yet only
very recently have transportation researchers begun to explore the role of social
interactions in individual transportation decisions ( Carrasco, et al., 2008; Paez and Scott,
2007). As explained by Heffner ( 2007) and summarized in the next chapter, the dominant
research approach in vehicle purchase behavior is based on the rational actor model of
discrete choice— representing the consumer as an actor that chooses among available
26
alternatives to maximize individual utility. Recent studies have attempted to include
factors of interpersonal influence in such models for alternative fuel vehicles, but still
rely on aggregated representations of behavioral dynamics, and ultimately yield little
insight into the true role of social interactions in vehicle purchase behavior. In this
dissertation, I employ a qualitative research design to explore such social processes in-depth—
to yield new empirical and theoretical insights and to help guide future research
efforts.
Responses to the survey described in Section 1.3 suggests the majority of new vehicle
buyers have little or no familiarity with the idea of a PHEV, and may erroneously believe
that existing HEVs can perform the same basic function as a PHEV, i. e., have the ability
to be refueled by gasoline and to be plugged into an electrical outlet ( Axsen and Kurani,
2008). This lack of awareness and understanding is both a constraint and opportunity. As
a market constraint, unaware consumers may simply fail to recognize or identify
compelling benefits of owning and operating a PHEV. On the other hand, the early
PHEV market in the U. S. may be viewed as a blank slate, with little preexisting
understanding of what a PHEV is or expectations of what it should be. Thus, the early
actions of consumers, automakers, governments, electric utilities and other stakeholders
could play an important role in establishing perceptions in the market. Similarly, the first
commercially available PHEV incarnations could set a standard for consumer
understanding and set expectations for functional, symbolic and pro- societal benefits. In
this dissertation, I seek to observe how such perceptions are established by consumers in
an interpersonal setting.
27
1.6 Summary and Scope of This Dissertation
This chapter introduced PHEVs as one type of electric- drive vehicle which includes a
wide variety of design and use possibilities. The purchase and operation of such a vehicle
might be classified under the broad umbrella of sustainable consumption practices— at
least more so than the use of conventional vehicles from a GHG emissions or gasoline
use perspective. Research suggests that about one half of U. S. new vehicle buyers are
currently able to plug- in such a vehicle at their home and two- thirds of those are also
interested in buying one. However, the market for such a technology will be strongly
determined by the types of benefits it can offer to consumers— including functional,
symbolic and pro- societal benefits— and how perceptions of such benefits develop as
commercialization begins. This dissertation explores the role of interpersonal influence in
the formation of stabilization of such perception, considering three main research
questions.
1. Does interpersonal influence play a significant role in the adoption of electric
drive vehicles?
2. If so, how can we characterize the interpersonal processes that impact consumer
perceptions of functional, symbolic and pro- societal attributes?
3. Under what social conditions might households adopt electric drive vehicles and
the pro- societal car? ( And how might policy create those social conditions?)
The remainder of this dissertation is organized as follows:
28
• Chapter 2 surveys and compares literature and perspectives that link interpersonal
influence to adoption behavior;
• Chapter 3 explains the qualitative research methodology I employed to observe
the role of interpersonal influence within a PHEV demonstration project at the
University of California, Davis;
• Chapter 4 depicts key empirical results from this methodology, seeking to address
the first question above;
• Chapter 5 applies the five theoretical perspectives outlined in Chapter 2 to the
research results in efforts to answer the second question;
• Chapter 6 addresses the third question by focusing on the stories of four
households that demonstrate changes in motivations;
• Chapter 7 returns to the theories of interpersonal influence to suggest an
integrated theoretical framework for future research; and
• Chapter 8 summarizes and concludes with policy considerations and suggested
directions for further research.
29
2 Consumer Behavior and Interpersonal Influence
As explained in the previous chapter, the question of how and why consumers buy new
products is central to the successful deployment of alternatively fueled and propelled
vehicles. Because human behavior is complex, researchers in various behavioral fields,
including sociology, anthropology, psychology and economics, often rely on models as
simplifications of behavior. Some models are based on elaborate theories, and others are
based on simple assumptions. In this chapter, I first review a general framework of
behavioral models relating to sustainable consumption, then focus in more depth on five
behavioral perspectives relating to the subject of this dissertation: the role of
interpersonal influence. 5 These five perspectives help to guide analysis in later chapters:
Chapter 3 describes the research methodology developed to explore these perspectives in
an empirical study; Chapter 5 applies each perspective to observed case studies and
assesses their validity; and Chapter 7 proposes an integrated theoretical approach based
on elements of these perspectives that proved useful in empirical application.
5 In section 1.4 I noted the inherent uncertainty in defining the purchase or use of a PHEV as pro- societal or
sustainable. From here on, in using terms like “ sustainable consumption” and “ pro- societal practices,” I
offer the same qualification as Jackson ( 2005, p1):
“… assessing the environmental impacts of specific behaviors or intentions is beyond the scope of this
document. It will concentrate instead on people’s pro- environmental attitudes and intentions and the
relation between these and their behaviors.”
In other words, I consider behavior to be sustainable or pro- societal if it may be perceived as such by the
consumer— leaving estimates of actual societal impacts to other research.
30
2.1 Models of sustainable consumption
Jackson ( 2005) identifies five broad categories of consumer behavior model, which I
depict in Table 3 according to two main factors: i) the assumed degree of the individual’s
cognitive deliberation and ii) accounting for individual versus social ( interpersonal)
motives. His first category is expectancy- value models, where behavior is the result of
individual choices which are “ supposed to be made on the basis of the expected outcome
from the choice and the value of those outcomes” ( p. viii). This category includes the
rational choice model, where an individual consumer is assumed to calculate the costs
and benefits resulting from several alternate courses of action, then chose the action
which maximizes their expected net benefit. Jacksons summarize three main assumptions
of the rational choice model ( p. vii):
1. “ individual self- interest is the appropriate framework for understanding human
behavior,”
2. “ rational behavior is the result of processes of cognitive deliberation,”
3. “ consumer preferences are exogenous to the model… they are taken as given
without further elaboration as to their origins or antecedents.”
31
Table 3: Models of consumer behavior, adapted from Jackson ( 2005)
Category Example Deliberative Unit of Analysis:
Individual- Social
Expectancy- value Rational choice Always Individual
Adjusted expectancy- value Theory of planned behavior Always Mostly individual
Normative Value- belief- norm Always Mostly individual
Habit Heuristic models Sometimes Individual
Sociality Symbolic interactionism,
structuration
Sometimes Mostly social
Take the simple example of a man purchasing an HEV, say a Toyota Prius. Following a
rational choice model, I might represent this man as having chosen the Prius from a set of
available alternatives, which included the Prius, a Toyota Corolla and Honda Civic. I
would assume that prior to making his choice the man had calculated his expected value
from each possible outcome, that is, the value to him of purchasing each vehicle. I might
represent his expected value as a function of several attributes of each vehicle, such as the
purchase price, the net present value of future fuel costs, horsepower and interior space—
each of which is weighted according to his set preferences. Through this process of
rational deliberation, the man chooses the vehicle which maximizes his own net- benefit,
in this case observed as the Prius. Perhaps he made his choice because his expected fuel
savings offset the Prius’ added purchase price, while horsepower and interior space were
not sufficiently different among the models in his choice set.
Jackson ( 2005) outlines several common criticisms of expectancy- value and rational
choice models. Such models neglect that human beings have cognitive limitations, both
in lack of access to information, e. g., future fuel prices, and an inability to rationally
process complex information, e. g. calculating net present value of future fuel
expenditures, and integrate this information into a metric of net benefit. Humans often
32
rely on heuristics, habits and emotions in decisions making— if a decision is made at all.
Further, such models’ exclusive focus on self- interest neglects the potential for social,
moral or altruistic motivations. Each of the next four categories of behavioral model
attempts to address one or more of these criticisms.
Adjusted expectancy- value models attempt to “ go beyond assumptions of rational choice
and unravel the psychological antecedents of consumer preferences” ( Jackson, 2005,
p. viii). One example is the Theory of Reasoned Action ( Ajzen and Fishbein, 1980) which
represents two antecedents to behavioral intention: i) an individual’s attitude towards the
behavior ( based on belief and evaluation of the outcome), and ii) their subjective norm
regarding the behavior, defined as the individual’s “ perception that most people who are
important to him think he should or should not perform the behavior in question” ( Ajzen
and Fishbein, 1980, p57) . Relating back to the Prius buyer example above, the Theory of
Reasoned Action would see the purchase decision as flowing in part from the buyer’s
attitude towards the purchase, based on his beliefs and evaluations of outcomes, which
again could be based on purchase price, fuel savings, horsepower, and interior space. But
this behavioral model also represents the buyer as considering whether his friends and
family think he should have bought the Prius, which adds a social motive to his
behavioral intention. However, as in the first category, most adjusted expectancy- value
models assume that decision making is a deliberative process, typically ignoring affective
motivations and habits, as well as the formation of attitudes.
33
Jackson’s third model category focuses on moral and normative factors, exploring the
roles of an individual’s values concerning the environment, e. g. ecological value theory,
or moral obligation to “ engage in pro- social behavior” ( p. 53). An example is Stern et al.’ s
( 1999) Value- Belief- Norm theory, which postulates that if an individual holds relatively
strong altruistic or biosphereric values, and weak egoistic values, they are more likely to
accept the New Environmental Paradigm, and thus “ develop a personal norm to engage in
pro- environmental actions” ( Jackson, 2005, p57). Thus, the Prius buyer may have
considered himself to be a charitable, selfless environmentalist, and views his
transportation choices as having environmental consequences that he is responsible for,
so he develops a personal norm to purchase and drive HEVs— if he considers such an
action to be pro- environmental. However, Stern et al.’ s model does little to explain how
such altruistic, biospheric and egoistic values develop in the first place.
The fourth category departs from the deliberative assumptions of the previous categories,
considering the roles of habits and simplifications in a world of limited cognitive
resources ( Jackson, 2005). Examples include models of heuristics, where individuals use
cognitive shortcuts, that is, they “ employ various approximation methods that enable
them to process the relevant information in making a decision” ( Tversky, 1969, p46) such
as “ elimination by aspects” ( Tversky, 1972), where an individual removes available
alternatives from the choice set based on certain attributes. If the Prius buyer was
uncertain how to compare the three vehicles with similar sizes and difficult cost
calculations, he may have relied on a heuristic: simply eliminating all non- hybrid options,
or all vehicles that weren’t available in blue. Further, individual responses can be
34
influenced by the framing of the decision ( Tversky and Kahneman, 1974)— the same
Prius buyer might have chosen differently if he was comparing the Prius with two
motorcycles, two other HEVs, or two luxury vehicles. The role of habit could also come
into play if the buyer was used to buying whatever sedan had the best fuel economy, for
example
Jackson’s final behavioral model category, sociality, moves beyond the individual as the
sole unit of analysis and attempts to account for the “ socially embeddedness of
environmentally significant behavior” ( 2005, p ix). An example is Blumers’ ( 1969) work
in symbolic- interactionism, which Jackson ( 2005, p71) summarizes according to three
key premises:
1. “ human beings act towards things on the basis of the symbolic meanings those
things have for them”
2. “ the meaning of such things is negotiated through social interaction”
3. “ in any given situation these meanings are handled in and modified by an
‘ interpretative process’ specific to the situation and the individuals involved.”
Thus, as noted in Section 1.4 of the previous chapter, a new technology can have
symbolic as well as functional value, and these symbolic values are negotiated through
social processes, where meanings can change and develop in different social contexts.
The Prius buyer may have associated the HEV with a positive symbol of “ environmental
responsibility” as well as a negative symbol of “ tree- hugging hippy.” He may have
35
consulted and observed his friends and family to learn which symbols they recognize, and
learned that the Prius would win him status among his outdoors friends, but earn snickers
among his coworkers. His purchase of the Prius and the social interactions that result
serve to further develop the symbolic meaning of the vehicle among his social groups.
Such a behavioral approach thus views sustainable consumption as occurring and
developing within a broader social arena.
Looking across his model categories, Jackson ( 2005, p89) highlights the importance of
“ integrative theories of consumer behavior” which attempt to encompass numerous
dimensions. An example is Giddens’ ( 1984) structuration theory, which concerns “ the
relationship between agency ( or human action) and structure ( the social institutions that
constitute the framework for human action)” ( Jackson, 2005, p89). Structuration attempts
to account for behavioral processes at the individual level, e. g. the Prius buyers desire to
own a new vehicle technology, as well as the social context, e. g. the support or rejection
he may experience in his social group, and the interactions between them, e. g. how his
purchase may help to normalize HEV ownership in his group. Taking all reviewed
categories of behavioral models into consideration, Jackson ( 2005, p. x) suggests that “ a
useful model has to account for: motivations, attitudes and values; contextual or
situational factors; social influence; personal capabilities; and habits.” I will return to this
suggestion in Chapter 7 when I seek to construct an integrative model of interpersonal
influence. Next I consider the use of behavioral models in the present application of pro-societal
vehicle purchase behavior.
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2.2 Applications to vehicle purchase behavior
As explained by Heffner ( 2007), the dominant behavioral model employed in research on
vehicle purchase behavior is the rational actor model of discrete choice— representing the
consumer as an actor that chooses among perceived available alternatives to maximize
their individual utility. Train ( 1980) constructed one of the earliest vehicle choice models
to include alternative fuel technologies ( electric vehicles, PHEVs— then called hybrids,
hydrogen and aluminum- air). The model specified vehicle attributes for each vehicle
option, including purchase price, operating cost, weight and performance, as well as the
demographic characteristics of the car buyer, and forecasted market shares of the
different alternative- fuels. Later models were built based on similar function- based
attributes, often using hypothetical consumer choice data ( stated preferences) to estimate
model coefficients ( e. g. Brownstone, et al., 2000; Bunch, et al., 1993; Calfee, 1985;
Potoglou and Kanaroglou, 2007) or using actual market data ( revealed preferences) ( e. g.
Wall, 1996). Some rational choice models have attempted to include less conventional
explanatory factors, such as Ewing and Sarigollu’s ( 2000) specification of attitudinal
variables regarding technology, the environment and locus of control. However, these
alterations still maintain the deliberative, individual- centric assumptions of expectancy-value
models. Because such models focus on the functional aspects of alternative- fuel
technology, their conclusions generally focus on the functional drawbacks relative to
conventional vehicles, such as increased purchase price, reduced storage space due to
batteries or fuel tank, limited range due to batteries, and increased refueling or recharging
time.
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Similar to Jackson’s broader criticisms of rational choice, some transportation researchers
argue against the almost exclusive use of this method to study new markets for vehicle
technology. Turrentine et al. ( 1992) discovered that many consumers had little familiarity
with electric vehicles or other alternative fuel technologies, and their so- called
preferences were non- existent or instable. Instead, consumers created and developed their
preferences with exposure to and discussion of the technology in question. These
researchers branched away from the rational choice framework, instead using an
“ interactive stated lifestyle- preference” techniques to simulate “ decision making contexts
designed from actual behavior of the household” and allowing for education and learning
process as part of the choice process ( Kurani, et al., 1994, p247). They later adapted these
techniques to a large- scale survey sample ( Kurani, et al., 1996; Turrentine and Kurani,
1998). By providing more extensive information to participants and creating realistic
decision making contexts, this line of research produced significantly different
conclusions than relatively simplistic rational choice studies— demonstrating how
households could adapt their lifestyles to new, limited- range vehicle technologies.
However, even this research assumed a largely deliberative model of consumer behavior,
and though decisions were observed at the household level ( as opposed to individual
completion of questionnaires), researchers did not account for the larger social context of
transportation decision making.
Only very recently have transportation researchers begun to explore the role of social
interactions in individual transportation decisions ( e. g. Carrasco, et al., 2008; Paez and
Scott, 2007). Specific to alternative fuel vehicles, several studies have attempted to
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introduce social factors to rational choice models, through the empirical estimation and
inclusion of parameters representing aggregated preference changes as a result of
increasing technology market share ( Axsen, et al., 2009; Mau, et al., 2008), word- of
mouth effects ( Struben and Sterman, 2008), and information search channels ( van
Rijnsoever, et al., 2009). However, these approaches rely on aggregated representations
of behavioral dynamics loosely connected to empirical findings from diffusion research
in other disciplines ( discussed next) and ultimately yield little insight into the role of
social interactions in vehicle purchase behavior. To better understand interpersonal
influence within the context of new vehicle sales, I now turn to a literature review of
different perspectives of interpersonal influence from a variety of disciplines and
applications.
2.3 Perspectives of interpersonal influence and adoption
Readers should note that interpersonal influence literature is confused by a myriad of
inconsistently used terminology. Manski ( 2000) explains how social interaction
researchers will typically “ borrow jargon from sociology or social psychology” ( p117)
and refer to loosely defined, sometimes interchangeable, concepts like “’ social norms,’
‘ peer influences,’ ‘ neighborhood effects,’ ‘ conformity,’ ‘ imitation,’ ‘ contagion,’
‘ epidemics,’ ‘ bandwagons,’ or ‘ herd behavior’” ( p127). He argues that this “ abundance
of concepts” ( p121) arises in part from the imprecise use of verbal reasoning rather than
formal, mathematical analysis of such. In this section I agree with Manski that in efforts
to explore social influence, “ the very first step must be to get the concepts right” ( p132).
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However, in this review of different research perspectives, I still must rely on verbal
reasoning— reviewed concepts are far too complex, uncertain and amorphous to be easily
or appropriately quantified at this stage, if ever.
One research perspective has provided the dominant conceptualization of new product
adoption: the diffusion of innovations ( DOI). DOI emphasizes the role of information
diffusing from innovators and early adopters to the remaining majority via interpersonal
communication. The DOI approach has several strengths which have warranted its
application and development in a wide array of disciplines, perhaps the greatest strength
being a simple language to facilitate sharing and learning across disciplines. However, I
argue that DOI has very important weaknesses which are particularly exacerbated when
applied to the adoption of technologies and ideas with both functional and symbolic— and
pro- societal, in particular— costs and benefits. Electric- drive vehicles are an example of
such complex innovations. I argue that electric- drive vehicles, as well as other
alternatively fueled vehicles, should be studied under a broader category of innovation,
which I call the pro- societal car.
In this section, I illustrate the strengths and weaknesses of DOI as one application of the
contagion perspective, which focuses on the role of information flow, then discuss four
alternative perspectives: conformity, which focuses on individual thresholds and
motivations to mimic others; dissemination as the intentional diffusion of information by
a core group or critical mass; translation as the tendency for various relevant social
groups to steer the path of technological development and negotiate interpretations; and
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reflexivity, which explains the motivations of individuals seeking to establish lifestyle
practices consistent with their self concept. I warn the reader that my summary of these
five perspectives is actually a simplification of dozens of complex research approaches
and theories. My intent is to present these five perspectives as an approachable synthesis
of other literature. I explain each perspective in as general terms as possible— typically
more general than the original authors intended— e. g. contagion, then focus on particular
approaches, e. g. DOI. Further, these perspectives are not necessarily exhaustive or
mutually exclusive. In fact, social network analysts often blend elements of contagion
and conformity.
In Section 1.4, I explained that electric drive vehicles and other pro- societal cars are
complex innovations. In addition to functional attributes, symbolic and societal attributes
are highly relevant. Upon surveying literature in various disciplines, it is clear that
research is muddled with varying and often confused terminology. A relatively neutral set
of questions helps to clarify such confusion. Following a similar framework to that
employed by Bruun and Hukkinen ( 2003), I present five questions to ask of each
perspective on interpersonal influence and adoption:
1. What is the innovation, and what attributes are important?
2. What are the system boundaries?
3. Who adopts earlier, and why?
4. Who adopts later, and why?
5. What drives adoption from earlier to later adopters?
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The first question addresses the object of analysis. Terms range widely, including
innovation, invention, new product, novelty, technology, practice, artifact, trait, symbol,
meaning and interpretation. While slight variations in terminology are trivial, differences
in concept are crucial; of particular importance is how the concept addresses ( or fails to
address) the four attribute categories presented in Table 2. The second question concerns
the boundaries of the system in which the innovation is being adopted, where terminology
includes the market, social system, social group, social network, or lifestyle sector.
System boundaries frame the analysis, determining who and what can play a role in the
adoption process, as well as the nature of relationships among these components. The
third and fourth questions address the fundamental concepts of adoption patterns: do
earlier adopters differ from later adopters in any important way other than timing of
adoption, and if so, how? Earlier adopters can be labeled innovators, inventors,
instigators, visionaries or organizers. Terminology for later adopters includes imitators,
the early and late majority, laggards, conformists, social learners, and followers. The fifth
question addresses the process of interpersonal interaction that ultimately drives
adoption, which also determines the name of each approach: contagion, conformity,
dissemination, translation and reflexivity. A summary of these approaches and questions
is presented at the end of the section in Table 4.
2.3.1 Contagion: Interpersonal communication
The contagion perspective focuses on social influence as the flow of information among
individuals. The term is borrowed from epidemiological studies of how diseases are
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spread through a population. Contagion can alternatively be called diffusion, a term
borrowed from physics that refers to the movements of a substance from higher to lower
concentration areas. While this perspective can apply to any social influence approach
that focuses on information flow, here I focus on DOI and social network analysis as
prevalent examples.
Diffusion of innovations ( DOI)
In the DOI approach, adoption is primarily driven by diffusion, “ the process in which an
innovation is communicated through certain channels over time among the members of a
social system… a special type of communication, in that the messages are concerned with
new ideas” ( Rogers, 2003, p5). The object of focus is the innovation, “ an idea, practice or
object that is perceived as new by an individual or other unit of adoption” ( Rogers, 2003,
p12). The likelihood of an innovation to successfully diffuse is hypothesized to depend
on five main characteristics: 1) relative advantage over the object it replaces, 2)
compatibility with existing values, experiences and needs, 3) complexity, 4) trialability,
and 5) observability of outcomes ( Rogers, 2003). Thus, an innovation is more likely to be
adopted if: it demonstrates advantage over previous technologies and competing
alternatives, it fits in with the current culture, it is not too complex for new users to figure
out, it can be tested before adoption and visible success can be demonstrated by previous
adopters.
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The setting of the diffusion process is the social system, “ a set of interrelated units that
are engaged in joint problem solving to accomplish a common goal” ( Rogers, 2003, p23).
Moore’s ( 1999) more business- oriented definition is that of a market, consisting of
potential customers with similar needs whom reference each other. This system of
potential adopters is divided into adopter categories, based on the empirical observation
of adoption rates following a bell- curve over time ( Figure 7).
Figure 7: DOI adopter categories
Time
Rate of Adoption
Innovators
Early
Adopters
Early
Majority
Late
Majority
Laggards
Source: adapted from Rogers ( 2003)
The first to adopt are the innovators, a sub- group characterized as obsessively
venturesome, progressive, cosmopolite individuals, usually with a love of technology,
and above average education and socioeconomic status ( Rogers, 2003). Next are the early
adopters who are characterized as visionaries who use extensive social networks to
spread information about the innovation to the masses. Following are the early majority,
late majority and finally the laggards. Each category is characterized as having slightly
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different motivations for adoption, where earlier adopters are more interested in the
functions of the innovations, and resistant later adopters are eventually influenced by peer
pressure and economic necessity. Bass ( 1969) provides an even simpler classification of
adopters with only two categories: innovators that are completely independent of others
in their purchase decision, and imitators that are influenced by innovators and other
imitators. In either variation, placement in adopter categories is determined by
innovativeness, “ the degree to which an individual or other unit of adoption is relatively
earlier in adopting new ideas than other members of the social system” ( Rogers, 2003,
p280).
In DOI, the adoption process is hypothesized to be driven by communication, including
word- of- mouth and mass media. Rogers ( 2003) classifies two types of information: 1)
knowledge, which includes basic awareness of the innovation’s existence, how it can be
used, and potentially its underlying principles, and 2) persuasion, which the persuaded
individual uses to form attitudes about the overall value of adoption. Both types of
information are thought to flow from individuals in the innovator category to those in
later adopter categories, with early adopters playing a particularly important role as the
gatekeepers between technology loving innovators and the majority. Moore ( 1999)
provides a frequently- cited revision to DOI, asserting that there is a substantial divide
between Roger’s early adopter and early majority categories. This chasm results from a
communication gap between individuals in these two categories, who don’t normally
communicate with one another. Moore claims that aggressively crossing this chasm is the
most important challenge for any new product.
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Under DOI, the adoption of an electric- drive vehicle, say an HEV, would primarily be
explored from a technological, functional focus— as a new technical device. The targeted
social system is the entire new automobile market, perhaps limited to buyers of vehicle
body styles in which an HEV is available. To anticipate the diffusion of HEVs, DOI
researchers look to new car buyers with higher education and socioeconomic status,
perhaps with a history of being the first to buy new technologies in the past ( either in
general or domain- specific, i. e., automotive). The motives of the first to buy HEVs, i. e.,
innovators, are explained by their general love of technology, along with their willingness
and resources to pay a premium to be the first to own and try out the new HEV drivetrain.
After gaining experience with this technology, such as testing performance, reliability,
and fuel savings, these innovators provide feedback within their social network that
diffuses to early adopters. Upon receiving this information through various
communication channels, early adopters may envision the HEV as having mass market
appeal, and through their channels of influence, accelerate the diffusion of positive HEV
information, potentially stimulating a jump in demand that eventually overtakes the
market. Heeding Moore’s ( 1999) notion of a chasm, the success of HEV adoption