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Egger, F.N.
(2001). Affective Design of E-Commerce User Interfaces: How
to Maximise Perceived Trustworthiness. In: Helander, M.,
Khalid, H.M. & Tham (Eds.), Proceedings of CAHD2001:
Conference on Affective Human Factors Design, Singapore,
June 27-29, 2001: 317-324.
Affective Design
of E-Commerce User Interfaces:
How to Maximise Perceived Trustworthiness
Florian N. Egger
IPO, Center for
User-System Interaction, Eindhoven University of Technology,
PO Box 513, 5600MB Eindhoven, The Netherlands.
Abstract
Successful
e-commerce user experience design depends on a large number
of factors. This paper focuses on consumers’ acceptance of
and trust in an e-commerce system, based on the transaction’s
value and perceived risk. The model of trust for e-commerce
(MoTEC) by Egger (2000) provides a framework making explicit
factors likely to affect customer trust. For each model
component, design principles are provided, along with more
concrete guidelines. It will be shown that the user
interface is only one element of the customer experience.
Designing for trust therefore requires user experience
strategists to look beyond the mere design of the web site
and pay attention to more general management and marketing
issues
Keywords
HCI, E-Commerce, User Experience, Trust
1. Introduction
As increasingly
more products and services are sold over the Internet, it
becomes all the more important to build up knowledge in
e-commerce-specific user interface (UI) and user experience (UX)
design. Whether a web site is an extension of a familiar
off-line company, or whether it is the only touch point with an
unknown company, consumers must be confident that they have
significantly more to gain than to lose when entering a
transaction. Losses can take the form of frustration, deception,
dissemination of confidential information, as well as wasted
time and money. The entire user experience must therefore be
designed to induce a positive affective state by strategically
addressing consumers’ concerns.
1.1 Consumer
Trust
The main UX
concept examined in this paper is consumer trust, as it
encapsulates the notions of uncertainty, vulnerability and risk,
characteristic of transactional relationships (Deutsch, 1960;
Doney & Cannon, 1997). Trust is defined as a type of belief
superior to faith and inferior to confidence. The
Faith-Trust-Confidence continuum, as defined by Arion et al
(1984), refers to the amount of available knowledge and cues on
which to base one’s belief. Thus, trust acts as a mental
mechanism, based on incomplete information, that helps reduce
complexity to allow for decision making under uncertainty (Luhmann,
1988; Kahneman et al, 1982).
Trust is seen
as a highly valuable element of business relationships, as it
fosters risk taking in economic transactions (Luhmann, 1988).
Two types of trust must be distinguished. The first type,
initial trust, refers to a new situation where, say, a
prospective customer assesses the trustworthiness of a merchant
based on third-party information and surface cues. The second
type, trust based on direct experience, presupposes an initial
transaction, followed by an evaluation of the outcome. As such,
it affects the long-term orientation of the relationship. In
this paper, the stress will be on designing for initial trust.
1.2 Research
Objectives
Given the
importance of trust in commercial relationships, there is a
clear need for substantive and methodological knowledge about
consumer trust in e-commerce.
Previous UX
research on trust has focused on graphic design (Kim & Moon,
1998), surface cues (Cheskin Research & Studio Archetype,
1999) and user experience design (Nielsen Norman Group, 2000).
While these studies all contribute to our knowledge about trust
design, none of them has attempted to start from an in-depth
theoretical account of trust to derive trust-specific design
principles. In addition, existing design guidelines have paid
little attention to the wider business and marketing issues
necessary to design not only a web interface but the entire
buyer-seller interaction.
The initial
phase of the author’s research dealt with substantive
knowledge and the development of a model of trust for e-commerce
(MoTEC; see 2.2 below). Readers interested in the theory
underlying the development of the model are referred to Egger
(2001). The objective of this paper is to show how the
descriptive model can systematically be used to derive design
principles that maximise consumers’ initial trust in an online
vendor.
2. Method
The approach
adopted in this research project was to start with a model that
identifies all the factors, be they on- or offline, likely to
have an effect on consumers’ perception of a vendor’s
trustworthiness. The general issue of trust was first analysed
from a psychological (Rempel et al, 1985) and marketing (Doney
& Cannon, 1997) viewpoint, which led to the identification
of a number of crucial factors for the development and
maintenance of trust. These factors were then integrated as
components in an analytical model. This model has been
iteratively tested and refined by means of user tests where over
60 subjects were tested on sites for online grocery shopping,
travel booking, private banking, as well as online marketing
services (Egger & de Groot, 2000). Since its formulation in
Egger (1998), the model has continuously been refined with new
research findings by the author and other sources. An overview
of the MoTEC model is presented below (Fig. 1).
Figure 1 – Overview of the
Model of Trust for Electronic Commerce (MoTEC)
The model is
based on the metaphor that people’s predisposition to trust
and pre-knowledge determine an initial trust value even before a
merchant web site is accessed. As one explores a new site for
the first time, the first impression made by a system, in terms
of graphic design and usability, will lead to a re-assessment of
that trust value. As one examines cognitively more demanding
factors, such as the company’s competence or the risk of a
transaction, one’s trust value is bound to change once again.
The fourth dimension, relationship management, refers to the
handling of inquires or orders over time. Whether communication
happens before or after ordering, the responsiveness and the
quality of the help may also affect one’s level of trust. This
model shows that trust can be affected by both emotion and
cognition, in both implicit and explicit ways. One should add
that the evaluation of interface properties does not necessarily
precede the evaluation of informational content; however, the
former, qua means, is often required for the latter.
Sections 3 to 6
will present the model’s four dimensions in greater detail.
The descriptions will be followed by implications for design, in
the form of design principles and more concrete guidelines.
3. MoTEC: Pre-interactional
Filters
The first model
dimension consist of pre-interactional filters. That is, factors
that can affect consumers’ trust in an online business before
any online interaction has taken place.
3.1. User Psychology
Research has
shown that individuals differ a lot in terms of their readiness
to trust another party. (Deutsch, 1960). Cultural factors have
also been reported to shape people's trust attitudes and
behaviours (Jarvenpaa & Tractinsky, 1999). For instance, it
has been found that Americans and Japanese trust more readily
than Chinese and French (Fukuyama, 1995). Another predisposition
is people’s trust in information technology (IT) and,
specifically, in the Internet. Generally, one’s expertise in
the underlying technology affects the extent to which the medium
is perceived to be reliable and trustworthy. Another
psychological filter is the person’s general attitude towards
e-commerce. Although a third of the population forms the
"early adopters of almost anything" (Keen, 1999),
two-thirds will need good arguments and the benefit of others'
experiences to feel confident enough to transact online.
Know the customers:
- Identify the customer segments
targeted by the company's marketing strategy.
- Establish a profile for each
group: pay particular attention to age, gender, cultural and
socio-economic background, as well as to likely personality
traits (Early adopters? Risk averse?).
- Determine their levels of
proficiency with IT, the Internet and e-commerce.
3.2 Pre-purchase Knowledge
This
sub-component refers to facts or preconceptions about a
particular industry and/or a particular company. For instance,
some people may have a rather negative perception of direct
marketing companies or second-hand car dealers. This entails
that these people will approach online systems of such companies
with a negatively biased trust value. Prior knowledge might also
include an individual’s offline experience with a specific
company. This experience can be both indirect and direct.
Indirect experience is mostly related to brand awareness, i.e.
knowing that a particular company exist and what it offers.
Direct experience, on the other hand, implies that one has
actively interacted with a particular business, be it physically
or through other media like phone, fax or mail order.
Examine attitudes towards the
industry:
- Analyse consumers’
familiarity with and perception of the industry.
- Determine the objective risks
characteristic of the industry.
- Determine the perceived risks
associated with the industry.
- Identify ways others have
addressed those risks and concerns, both off- and online.
Analyse the company’s brand
equity:
- Determine the company’s
brand position with respect to its competitors.
- Determine consumers’
perception of the brand: reputation, quality of experiences,
expectations.
- Identify any associations and
values connected to the brand.
- Define a clear online user
experience strategy.
3.3 Transference
In addition to
one’s own experience with a company, one can also rely on the
advice of trusted sources of information. The author’s
research has found that people rely a lot on word-of-mouth, a
form of viral marketing. Experiences, good and bad, spread
rapidly among the web of trust consisting of close friends,
family or colleagues. Other trusted sources in the offline world
are traditional media like newspapers or television programs.
Online, people can also be influenced by what they read on
trusted web sites, e-zines, newsgroups, bulletin boards or
mailing lists. In addition, a site’s presence and ranking in
directories or search results can also affect the perception of
its trustworthiness.
Take advantage of trusted
sources of information:
- Identify and use traditional
sources of information trusted by the target population.
- Identify and use online
channels trusted by the target population.
- Use on- and offline viral
marketing techniques to raise awareness of the web site.
4. MoTEC: Interface Properties
Interface
properties refer to the surface cues that make or brake the
first impression made by a web site. Given people’s
confirmation bias, first-time visitors will unconsciously seek
to confirm their first impression rather than falsify it. The
two factors under consideration here are branding and usability.
4.1 Branding
When accessing
a site for the first time, the first response is likely to be an
emotional one. The appeal of the interface, in terms of graphic
design and layout, can directly affect the acceptability and
usage of the system. More specific attributes of branding are
the easy identification of the company and its activity sector,
e.g. by means of a prominent logo and slogan. Another element
likely to have a significant influence at this stage is how
prominently the company presents its main selling points. This
can arouse people’s curiosity and motivate them to explore the
site further. Since the first contact is all about presentation,
professionalism is also a key factor. For instance, outdated
content, broken links and typographical errors have all been
reported to decrease a site’s credibility and trustworthiness
(Nielsen Norman Group, 2000; Fogg et al, 2001).
Generally, the more a company is perceived to have invested in
its web site, the less likely it is perceived to act
opportunistically by betraying customers’ trust, as it would
have more to lose than to gain.
Take advantage of a
familiar brand experience (traditional
companies):
- Transpose trusted offline
brand attributes to the web site (colour scheme, style guide,
etc.).
- Ensure that the different
channels all convey the same image.
- Integrate offline marketing
campaigns into the design of the web site.
Create an interactive
brand experience (dotcoms):
- Take advantage of people’s
familiarity with related on- and offline companies.
- Meet or exceed people’s
expectations about the look-and-feel and functionality of the
web site.
- Take advantage of the medium’s
interactivity for efficient experience branding.
- Complement online with offline
branding channels to facilitate the transfer of trust to the
web site.
Convey a
professional image:
- Invest considerable resources
for brand positioning, UX strategy and implementation.
- Allude to the company’s
investment in its operations and the size of its customer
base.
- Pay attention to details, be
they graphic, textual or navigational.
- Have a domain name consistent
with the brand or company name.
4.2 Usability
When
prospective customers start exploring a web site, the ease and
the efficiency with which they can access relevant information
can affect how much they feel in control of the site. Factors
that come into play are the architecture of the information, the
familiarity of metaphors and the transparency of terminology.
Any feature that lets visitors familiarise themselves with the
system or that guides them through the shopping process can also
facilitate the human-computer interaction. Specifically,
confirmations of actions, process feedback and constructive
error messages all help visitors feel in control of the system.
An aspect related to usability is the reliability of the system,
which can be affected by factors both inside and outside the
merchant’s control. Generally, ease-of-use is perceived as a
sign that the company understands, cares for and respects its
customers.
Please note
that we will not expand on general principles for web design
(cf. Nielsen, 1999).
Provide easy
access:
- Design for cross-platform and
cross-browser compatibility.
- Avoid the need for plug-ins
and downloads on the homepage.
- Only use plug-ins if they add
value to the content.
Be
customer-centric:
- Structure the site in
accordance with customers’ domain model and expectations.
- Present information in a way
relevant to the customer: e.g. thoroughly test localised
systems.
- Minimise click stream for
greater efficiency and satisfaction.
- Learn and anticipate customers’
preferences: e.g. personalisation over time.
Let the
customer be in control:
- Support the browsing
behaviours of both novice and expert users.
- Inform customers about the
procedures required to transact: e.g. overview of steps.
- Provide clear feedback to user
actions: allow for easy error management.
- Allow for customisation: e.g.
content, language or measurement units.
5. MoTEC:
Informational Content
When exploring
a site further, customers will start assessing the information
they encounter. This phase can be split into two main processes.
The first is an evaluation of the company’s competence, while
the second is an evaluation of the risk associated with a
potential transaction
5. 1 Competence
5.1.1 Products & Services
Whether people
have a precise goal in mind or simply browse through a site,
detailed descriptions of the available products and services
help them make informed decisions about their purchases. The
credibility of the information has also been observed to be very
important as unreasonable or misleading claims can say a lot
about a company’s ethical standards and trustworthiness.
Features that reduce user costs, such as comparisons with
competitive products, may also be perceived as a sign of honesty
and competence. In addition, the provision of related content,
if relevant, can also be interpreted as the company truly
understanding its customers’ needs. Evaluating financial costs
also comes into the picture at this stage, as it feeds into the
prospective customer’s cost-benefit analysis.
Create value:
- Create added value that may
motivate and justify risk taking.
- Meet or exceed customers’
expectations about the quality of descriptions: e.g.
multimedia features.
- Support the decision-making
process: e.g. by offering comparisons or alternatives.
Be credible:
- Back up objective content with
data and references: e.g. external links.
- Provide credentials and
affiliations of reviewers.
- Acknowledge any content that
is sponsored by or affiliated to another party.
Be transparent:
- Display all costs prominently
and early in the process.
- Provide explanations as to
unusually high or low prices.
- Be clear as to any implicit
costs: e.g. cost of ownership.
5.1.2 Company
When selecting
merchants, prospective customers will try to infer a party’s
trustworthiness from its past behaviour and performance. It is
therefore important that people be able to clearly identify the
party (or parties) that will be involved in the transaction.
Contact details and photographs of people behind the company
also help convey a real-world feeling (Fogg et al, 2001).
Given the moral dimension of trust, people will be receptive to
cues conveying a company’s philosophy and values. In addition,
little known e-commerce sites that have created strategic
alliances with high-profile and trusted companies are likely to
benefit from those partnerships in terms of added credibility.
Present the
company:
- Provide complete contact
details: e.g. physical address, phone and fax numbers, etc.
- Provide information about the
company’s legal status, associations and partnerships.
- Show that there are real
people behind the company: e.g. provide key names and
photographs.
Describe the
company’s achievements:
- Provide company background:
e.g. history and development.
- Provide a portfolio of
high-profile customers.
- Provide investors information:
e.g. stock price and annual reports.
Communicate the
company’s values:
- Stress moral values in the
company’s philosophy.
- Mention sponsoring and charity
activities the company is involved in.
5.2 Risk
5.2.1 Security
Assuming a
prospective customer is interested in a given product, the next
step will be to assess the security of an online transaction.
Cues that help this process are an explicit security policy, the
use of encryption on order forms, as well as the involvement of
trusted third parties.
Address
security concerns up-front:
- List the measures taken to
ensure that data is transferred, processed and stored
securely.
- Provide prominent links to the
security policy.
- Mention what hardware and
software solutions are used: provide external links to
providers.
- Complement browser feedback
with text to inform users that they are on a secure page.
- Provide several payment
options.
Provide
reassurance in case of fraud:
- Be clear about consumers’
liability: e.g. policies of credit card companies.
- Provide consumer redress
mechanisms and financial compensation.
5.2.2 Privacy
In addition to
security issues, people may also want to investigate information
provided about the company’s privacy policy. Typically, a
privacy policy makes explicit the use and dissemination of any
personal information collected on the site. When registration is
required, the type of personal information required in
registration forms can be quite determinant, as details judged
to be irrelevant for the transaction are usually not given or
made up. Once a personal profile has been created on a web site,
the ease with which details can be accessed and modified also
contributes to a feeling of control.
Provide a
privacy policy:
- Communicate the company’s
commitment to the privacy of its customers.
- Provide prominent links to the
privacy policy.
- Be audited by and display the
seals of an independent trusted third party.
Let customers
be in control of their data:
- Delay the need for
registration as long as possible.
- Give customers a complete
overview of the information required in registration forms.
- Justify the inclusion of
seemingly irrelevant details.
- Provide easy means to access
and modify data.
5.2.3
Contractual terms
Every
commercial transaction comes with its own set of terms and
conditions. Consumers judge the competence and the
professionalism of a company by the presumed quality and
validity of any warrantees, return policies or customer service.
Unexpected and unreasonable obligations on the part of the
customer once a product or a service is purchased are also
likely to affect customers’ trust.
Be transparent
about the fine print:
- Strive to produce legal
documents that are easily understandable.
- Check that terms and
conditions are compatible with the legislations of the target
countries.
6. MoTEC:
Relationship Management
Relationship
management reflects the facilitating effect of timely, relevant
and personalised vendor-buyer interactions on trust development
(pre-purchase) and maintenance (post-purchase).
6.1
Pre-purchase
In the case a
prospective customer has a question, it should be easy to get in
touch with the company. Different means of contact will cater to
different needs. Facilitating contacts can also be perceived as
an indication that the company really cares for its customers.
It also helps overcome the lack of face-to-face interaction.
Once contact has been initiated by the customer, it is important
that the company’s response be prompt and informative. Indeed,
if a visitor never gets an answer to his transaction-critical
question, he is not very likely to buy from that vendor.
Immediate feedback that the customer’s enquiry is queued for
processing can help communicate responsiveness. In addition to
the promptness of the reply, its quality in terms of relevance
and completeness is also of paramount importance. Customers
value a personal touch, e.g. that they are addressed by their
name or that the message is written by an identifiable
individual.
Provide
different means of contact:
- Provide traditional means of
contact: e.g. postal address, phone and fax numbers.
- Provide online means of
contact: e.g. e-mail addresses or instant messaging.
Handle customer
inquiries efficiently:
- Provide feedback that
inquiries are queued for processing.
- Reply to e-mail inquires
within 24 hours.
- Provide complete and
personalised responses.
6.2
Post-purchase
Once an order
has been placed, customers generally value a confirmation of
their order. Some vendors propose a tracking facility that lets
customers check the progress of their order. This
contributes to the transparency of the process and puts the
customer in control of the situation. Fulfilment is an
importance part of the customer experience. It includes the
physical delivery of an order to the customer, its condition,
presentation, packaging, as well as the correctness and
completeness of the order. Should something be wrong with the
order or should help be required, the ease with which customer
service can be notified is crucial to the maintenance of trust.
Besides, the amount actually charged by the company should be
identical as the amount authorised through the online payment
system. The way problems are solved all put consumers’
trust in a vendor to the test.
Provide
feedback about the order:
- Send a confirmation message
immediately after a customer has placed an order.
- Allow customers to track
orders in real time.
- Make it easy for customers to
modify and cancels orders.
Choose
trustworthy commercial partners:
- Choose reliable partners for
the web site: e.g. hardware, software, hosting, etc.
- Choose reliable partners for
the logistics: e.g. for warehousing, packaging, delivery, etc.
Provide an
effective after-sales service:
- Make it easy to return
products and get refunds.
- Bear in mind that it is
cheaper to retain satisfied customers than to acquire new
ones!
7. Discussion
It is
noteworthy that the design principles presented in this paper
partly overlap with the findings made by Cheskin Research &
Studio Archetype (1999) and the Nielsen Norman Group (2000). The
novelty of the present approach lies in the scope of the
knowledge it produces. As was mentioned in Section 2, the first
phase of this research dealt with the development of the MoTEC
model. The model is based on a variety of theoretical accounts
of trust, as well as on numerous empirical studies. The
iterative development of the model, by means of several
applications and evaluations cycles, ensures that the model
elements are coherent and complete. The stress of this paper was
to show how descriptive knowledge about the trustworthiness
evaluation process could be translated into methodological
knowledge for trust design.
The wide scope
of the model is reflected in the three types of design
principles that were produced:
- Trustworthiness can be
communicated before customers have accessed the web
site (branding);
- Trustworthiness can be
communicated during the online interaction (UI and UX
design);
- Trustworthiness can be
communicated after the online interaction (customer
service, fulfilment).
The affective
design of e-commerce user interfaces must therefore be placed in
the wider context of customer experience strategy. It follows
that the traditional scope of Human-Computer Interaction (HCI),
viz. "a user interacting with a system", must be
extended to "a customer interacting with a company" if
one wants to communicate trustworthiness effectively. This
redefines the role of UX designers, as they will have to
collaborate very closely with management and marketers to
develop a common and consistent strategy.
7.1 Limitations
One should note
that keeping the design principles too high-level comes at a
price. Indeed, it sacrifices the direct applicability of the
principles by UX strategists and designers. Although each
principle was illustrated by concrete guidelines, it was felt
that one needs high-level design principles to gain a general
understanding of the trust issues in business-to-consumer (B2C)
e-commerce. These general design principles can then be adapted
to different industries and business models. Indeed, systems for
healthcare services, online banking or online gambling all come
with their own set of trust issues. In other words, these
services would attach different weights to the different model
components.
7.2 Further
Research
The author’s
research will concentrate on the iterative development of the
MoTEC model and its applications. In addition to the design
principles, three further methodological tools will be
developed: a questionnaire that measures consumer trust, a
checklist for expert reviews, as well as a more structured
trust-specific design method. These tools will be validated by
means of case studies in different industries. For research
updates, please refer to: http://www.telono.com.
8. References
Arion, M, J.H. Numan, H.
Pitariu & R. Jorna (1994). Placing Trust in Human-Computer
Interaction. Proc. 7th European Conference on Cognitive
Ergonomics (ECCE 7): 353-365.
Camp, L. J.
(2000). Trust and Risk in Internet Commerce, The MIT
Press.
Cheskin
Research & Studio Archetype (1999). Ecommerce Trust Study.
Available at:
http://www.studioarchetype.com/cheskin/
Deutsch, M.
(1960). The Effect of Motivational Orientation Upon Trust and
Suspicion, Human Relations (13): 123-139.
Doney, P.M.
& J.P. Cannon (1997). An Examination of the Nature of Trust
in the Buyer-Seller Relationship. Journal of Marketing,
Vol. 51: 35-51.
Egger, F.N.
(1998). Increasing Consumers' Trust in Electronic Commerce
through Human Factors Engineering. Unpublished Master of
Science (Ergonomics) Thesis, University of London..
Egger, F.N. (2000).
"Trust Me, I'm an Online Vendor": Towards a Model of
Trust for E-Commerce System Design.
in: G. Szwillus & T. Turner (Eds.): CHI2000 Extended
Abstracts: Conference on Human Factors in Computing Systems,
The Hague (NL), April 1-6, 2000: 101-102, ACM Press.
Egger, F.N.
& B. de Groot (2000). Developing a Model of Trust for
Electronic Commerce: An Application to a Permissive Marketing
Web Site. Poster Proceedings of the 9th International
World Wide Web Conference, Amsterdam (NL), May 15-19,
2000: 92-93, Foretec Seminars Inc.
Egger, F.N.
(2001). Consumer Trust in E-Commerce: From Psychology to
Interaction Design. In an upcoming book by the Enabling
Electronic Commerce project. Info at: http://cwis.kub.nl/sobu/eec/
Fogg, BJ,
Marshall, J., Laraki, O., Osipovich, A., Varma, C., Fang, N.,
Paul, J., Rangnekar, A., Shon, J., Swani, P. & M. Treinen.
(2001). What Makes Web Sites Credible? A Report on a Large
Quantitative Study.
in: Jacko, J.A., Sears, A., Beaudoin-Lafont, M. & R.J.K
Jacob (Eds.): CHI2001 Proceedings: Conference on Human
Factors in Computing Systems, Seattle, WA (USA), 31 March- 5
April, 2001:61-68, ACM Press.
Fukuyama, F.
(1995). Trust: The Social Virtues and the Creation of
Prosperity, Free Press, New York.
Jarvenpaa, S.L.
& N. Tractinsky (1999). Consumer Trust in an Internet Store:
A Cross-Cultural Validation. Journal of Computer-Mediated
Communication, Vol. 5 (2).
Kahneman, D.,
Slovic, P. & A. Tversky (1982). Judgments Under
Uncertainty. Cambridge Univ. Press.
Keen, P. (1999). Electronic
Commerce Relationships: Trust By Design. Prentice Hall.
Kim, J. &
J.Y. Moon (1998). Designing Emotional Usability in Customer
Interfaces – Trustworthiness of Cyber-banking System
Interfaces. Interacting with Computers, Vol. 10: 1-29.
Luhmann, N.
(1988). Familiarity, Confidence, Trust: Problems and
Alternatives. Gambetta, D. (Ed.) (1988). (1988). Trust:
Making and Breaking Cooperative Relations, Basil Blackwell.
Nielsen, J. (1999). Designing
Web Usability: The Practice of Simplicity. New Riders
Publishing.
Nielsen Norman
Group (2000). Trust: Design Guidelines for E-Commerce User
Experience. Available at: http://www.nngroup.com/reports/ecommerce/trust.html
Rempel, J.K.,
Holmes, J.G. & M.P. Zanna (1985). Trust in Close
Relationships. Journal of Personality and Social Psychology,
Vol. 49 (1): 95-112.
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