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User Perspectives on Blockchain
Technology: User-Centered Evaluation
and Design Strategies for DApps
Hyeji Jang1, Sung H. Han1, and Ju Hwan Kim2
1Department of Industrial and Management Engineering, Pohang University of Science and Technology, Pohang, Korea
2Department of Creative IT Engineering, Pohang University of Science and Technology, Pohang, Korea
Corresponding author: Sung H. Han (e-mail: shan@postech.ac.kr)
This research was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No.
NRF-2019R1A2C1086366), and by the Ministry of Science and ICT (MSIT), Korea, under the Information Technology Research Center
(ITRC) support program (IITP-2018-0-01441) supervised by the Institute for Information & Communications Technology Promotion (IITP).
ABSTRACT Emerging technologies have played an important role in driving major changes in human
society. However, the advent of most technologies is typically initially accompanied by confusion; this is
often because technology developers overlook the user perspective. This study was conducted to
systematically determine the fundamental causes of problems that users encounter when they interact with
blockchain technology, one of the promising emerging technologies today, and to suggest relevant design
strategies. To this end, usability evaluation was conducted for the KDEX decentralized exchange
application. To ensure the effective identification of the significant usability problems, heuristic evaluation
with four experts and usability testing with 23 experimental participants were carried out. The results
obtained show that more user-centered design is necessary to enable the widespread use of decentralized
applications. Based on the experimental findings, actionable design strategies that facilitate the effective
utilization of emerging technologies are suggested. The proposed strategies are expected to enable users to
easily understand and navigate applications based on these technologies.
INDEX TERMS Decentralized application, decentralized exchange, heuristic evaluation, usability testing,
user-centered approach
I. INTRODUCTION
The term “emerging technologies” refers to radical
technologies in the early stages of development that have a
high potential for application in society in the near future [1,
62, 63, 64]. These technologies have been developing at a
rapid rate, and some of them have been expanding their
influence on the day-to-day activities of people. For
example, in just 30 years since its appearance, the World
Wide Web (WWW) has completely changed human society.
Several business areas have declined, and internet-based
companies such as Amazon and Google have grown on a
global scale. Since the release of Apple’s first iPhone in
2007, the use of smartphones has rapidly increased.
Eighteen million iPhone 11 were sold just in the first
quarter of 2020; today, they serve as powerful portable
computers. In terms of industrial impact, emerging
technologies are considered to have the potential to create
new industries or transform existing ones [2, 3]. Therefore,
businesses must focus on emerging technologies to retain
and engage customers; indifference to emerging
technologies and the changes they bring often leads to
elimination from the market.
Interest in new technologies is not sufficient to lead
future markets. It is also necessary to understand the novel
contexts in which these technologies interact with people,
in addition to the difficulties that arise from new
technologies [3, 4]. Technological innovation is
accompanied by new types of interactions. In other words, a
new technology implies a new user experience (UX).
Although exploring the applicability of technology is
important, the technology can be left unused if developers
do not consider UX. The success of technologies that are
widely used in our daily lives occurred because there was
deep consideration of the user interacting with the technical
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aspects. The initial emergence of the Internet involved very
little concern for users, thereby resulting in user confusion.
Decades later, the Internet has been playing an increasingly
important role in the world, and extensive research has been
conducted on UX relating to factors such as screen layout
and navigation [80]. The widespread usage of smartphones
would also have been impossible without research on new
experiences introduced by touch interaction, a completely
new type of human–computer interaction for its time.
Indeed, emerging technologies are ahead of the general
users’ ability to understand and utilize them. Technology is
extremely powerful and has the ability to change the world;
however, it cannot reach its full potential unless people feel
the need to use it. Several researchers agree that the
perspective of the user should be focused on instead of the
technology itself to ensure the success of an emerging
technology [65, 79]. Designing new experiences is a
process that facilitates a relationship between technology
and users; thus, balanced research must be conducted from
both perspectives. When applying an emerging technology,
developers should assign equal importance to the UX
design strategy and the development method.
Blockchain was selected as one of the top five
technologies of 2018 in the Gartner hype cycle of emerging
technologies [6, 7]. Further, it is receiving attention as a
promising technology because it is expected to solve the
limitations of existing centralized networks through
advantages such as anonymity and transparency. Several
researchers have asserted that the significance of
blockchain technology in future societies will be similar to
that of the Internet itself [8, 66]. Although the technical
characteristics of blockchain can introduce considerable
changes to users, few studies have reviewed the new
changes introduced by blockchain technology from the user
perspective. This study was conducted to determine the
factors that impede the success of emerging technologies
from the user perspective. To this end, a user-centered
approach to blockchain technology was considered. Experts
on both UX and blockchain conducted a heuristic
evaluation, and a group of general users participated in user
testing on a decentralized exchange to identify issues that
impede the use of a decentralized application (DApp). The
testing results indicated the major hurdles of DApp. Based
on the derived problems, a DApp design strategy is
presented.
The main contributions of this paper are as follows:
1) Factors hindering the use of DApps are explored
through systematic usability testing. In addition to
expert evaluation, the behavior of users was observed
to identify usability problems in DApps.
2) Design strategies for the successful introduction of
DApps are suggested. These strategies are obtained by
analyzing the problems identified based on the user
perspective. The proposed strategies can be applied to
other emerging technologies beyond blockchain.
The remainder of this paper is organized as follows.
Section 2 gives an overview of blockchain technology,
decentralized exchange, and the user-centered approach.
Section 3 discusses the current status of user-centered
research on blockchain technology. Section 4 outlines the
method used in this study. Section 5 presents and analyzes
the results of the study. Section 6 introduces and discusses
the major hurdles facing the introduction of blockchain
technology identified in this study. Section 7 proposes
considerations for DApp designers. Finally, Section 8
concludes this paper.
II. BACKGROUND
A.
BLOCKCHAIN AND ITS APPLICATIONS
Blockchain refers to a technology that stores a set of data
(called a block) in a distributed environment in the form of
a “chain” based on a peer-to-peer (P2P) network [9]. The
advantage of a centralized network is that all transactions
are centrally recorded and maintained, reducing the
recording cost. However, centralized management forces
the participants to rely heavily on trust in the central
institution [10]. In the blockchain network, the ledger in
which transaction information is recorded is distributed to
all network participants rather than a central institution.
When a new transaction occurs, it is recorded on a new
block, which is then added to the end of the existing chain
of blocks. All participants repeatedly store and maintain the
ledger to reflect the new transaction. Through this process,
a pure P2P network can be implemented in a stable manner.
Blockchain networks have several characteristics that
differ from those of centralized networks. For example,
blockchain networks do not handle the private information
of a user during a transaction [11]. Through data encryption,
a transaction can proceed in a manner that can identify but
not characterize an individual [12]. These characteristics
protect the privacy of users at a higher level compared to
traditional payment methods that require personal
information such as bank accounts and credit cards [13].
Further, all blockchain network participants can access all
transaction data, and modifying or deleting data recorded
on the blockchain have an extremely high computational
cost [14]. Thus, data recorded on the blockchain has high
transparency and traceability
With its characteristics, blockchain technology can help
increase the competitiveness of services. It is being actively
considered in several service fields, including healthcare,
transportation, food, and energy [15, 16]. In addition, it has
received significant attention in the field of finance because
it effectively prevents fraud (such as multiple payments) in
transactions between individuals without intermediary
support.
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B.
DECENTRALIZED EXCHANGE
The use of tokens is very important for several DApps.
Tokens are issued with a special purpose, and they function
like coupons in a system [15, 17]. Tokens function as
monetary incentives to drive desirable user behavior in
many DApps [18, 19, 20, 21, 22]. Users can gain monetary
benefits by exchanging tokens obtained as rewards for
contributions with cryptocurrency or fiat money through a
cryptocurrency exchange. Further, at cryptocurrency
exchanges, a certain type of cryptocurrency can be
purchased using fiat money for use within the DApp that
utilizes the cryptocurrency. Cryptocurrency exchange is
essential for the expansion of DApps because it functions as
a monetary intermediary between the DApp and the real
world. Cryptocurrency exchanges such as BKEX, P2PB2B,
and MKC are being operated actively. As of 2017, the
value of cryptocurrency exchanges grew to over 25 billion
dollars [23].
The majority of exchanges currently in operation are
implemented on a centralized network [24, 25]. However,
centralized cryptocurrency exchanges have several
disadvantages. For example, transaction information is
centrally managed, such as in banks, and users cannot take
complete control of their cryptocurrency. The central
institution can abuse its power and arbitrarily block certain
users or halt transactions. Further, centrally managed data
are vulnerable to external attacks [9].
As an alternative approach, blockchain has been applied
to implement cryptocurrency exchanges. Currently, several
decentralized exchanges such as EtherEx, Coinffeine, and
KDEX are in operation. The decentralized exchange builds
a P2P network such that users have complete control over
their assets. By introducing blockchain to a cryptocurrency
exchange, high transparency, security, and anonymity can
be guaranteed [26].
C.
USER-CENTERED DESIGN APPROACH AND
USABILITY TESTING
The term “user-centered design” first appeared in the 1980s
[72]. User-centered design refers to a design philosophy
that places the needs, wants, and limitations of end users at
the center of the design process of a product or service [73,
78]. User participation is essential for user-centered design;
although user-centered design requires a considerable
amount of time and cost, it enables efficient development
by minimizing the redesign stage, thereby enhancing the
developer's understanding of user behavior. Further, the
problems faced by the user can be specifically defined, and
the most effective solutions can be derived [74].
There are many ways users can participate in the design
process. In the early stage, requirements can be derived,
and desirable task sequences can be collected through
interviews, focus groups, and on-site observations. In the
final stage, user satisfaction or usability criteria can be
quantitatively measured through usability testing and
questionnaires [75]. Among user-centered design
approaches, usability testing is recognized as an effective
approach to derive the difficulties of end users specifically
[47]. Usability is a term that can be defined as usable or
useful [73], and it refers to how easily a user can perform a
task using a product or service [76]. As technology has
become increasingly complex, usability testing has become
an essential consideration in today's product and service
development to minimize development costs and attract
users effectively [77, 79].
III. BLOCKCHAIN TECHNOLOGY AND THE USER-
CENTERED APPROACH
Blockchain technology is accepted as a promising emerging
technology in both academia and industry. It is expected to
introduce a revolution similar to the emergence of the
Internet [16, 27]. Although public awareness of blockchain
technology has increased very rapidly in the past few years,
the widespread application of blockchain has not been
achieved yet [28, 29]. In fact, among about 86,000
promoted blockchain projects, only 8% have survived [30,
31].
Several studies have attempted to identify the hurdles in
the application of blockchain technology. The lack of
standardization, the disruption of development caused by
regulations, and problems related to users' understanding
and awareness of blockchain technology have been noted as
major barriers [32]. Among these, many researchers have
pointed out that developers’ misunderstanding of DApp
users is the foremost problem [15]. Because blockchain
technology remains an unfamiliar concept for the majority
of users, it is difficult to grasp the intrinsic value of
blockchain technology, and a high entry barrier is formed.
As user-related issues have become increasingly important
in recent times, experts have emphasized the urgent need to
improve the user perception and experience related to
blockchain technology [4, 29]. In particular, to expand the
use of blockchain technology, it is considered important to
create an environment that is accessible to users that are not
interested in cryptocurrency or blockchain technology but
are interested in using DApps [33]. However, only a few
studies have attempted to understand DApp users. Thus,
several currently operating DApps have fundamental
problems because of lack of understanding of its users.
A.
USER-CENTERED APPROACH TO BLOCKCHAIN
TECHNOLOGY
Blockchain has great value; however, its adoption is slow
compared to its potential benefits [26]. A lack of
understanding of users is emphasized as the primary cause
of this phenomenon. To solve this problem, efforts are
being invested in understanding blockchain technology
from the perspective of the user, which is called a user-
centered approach. Table I summarizes the results of a
literature survey for a user-centered approach to blockchain
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technology. Early research focused on investigating the
perception of cryptocurrencies rather than DApps. Several
studies identified motivations for using Bitcoin, which is
one of the most popular cryptocurrencies, through
interviews [34, 35, 36]. With the active development of
DApps, research has gradually increased. Ma and Pan [4]
and Meeuw et al. [37] suggested measures for improvement
by collecting user's opinions on data structures and page
layouts. Glomann et al. [29] interviewed experts to
ascertain the UX issues faced in blockchain applications.
TABLE I
Existing studies with a user-centered approach to blockchain technology
Study
Purpose
Method
Khairuddin et al.
[34]
Exploring the motivations
for using Bitcoin.
User interview
Gao et al. [35]
Investigating the
motivation for using and
requiring Bitcoin.
User interview
Sas and
Khairuddin [36]
Exploring the motivation
for using Bitcoin from a
trust perspective.
User interview
Meeuw et al. [37]
Proposing a data structure
for energy transaction
using blockchain.
User interview
Ma and Pan [4]
Investigating effective
page layouts in blockchain-
based transactions.
Eye tracker, user
interview
Glomann et al.
[29]
Exploring UX issues in
blockchain applications.
Expert interview
Although several blockchain studies have been
conducted, the majority of them were aimed at applying
technology or facilitating system development. Few studies
have explored the lack of widespread acceptance of
blockchain technology from the user perspective. Whereas
some recent studies have considered a user-centered
approach to DApps, the majority of them have been
performed in very limited contexts with specific purposes,
including the improvement of structures or layouts.
Glomann et al. [29] examined the overall UX of DApps
through expert interviews; however, experts already have a
strong understanding of the technology, and thus, they do
not appropriately represent general users. Therefore, to
overcome the limitations of existing studies, it is necessary
to identify concrete problems in DApps and deeply analyze
these problems through the cooperation of experts and
general users.
B.
USABILITY OF DAPPS
Previous studies attempted to collect users’ experiences and
opinions on blockchain technologies by conducting
interviews. Gathering experience in an uncontrolled
scenario helps to gain a broader understanding of a user's
experience with the technology; however, it is insufficient
to elicit specific problems affecting usability. Because poor
usability becomes the main factor that impedes the use of
emerging technologies, improving usability should be dealt
with very importantly among the various other attempts to
achieve a user-centered approach [38]. In this context,
usability testing can be an effective approach to gain insight
into the user perspective [39]. In particular, experiments
with real users play a very critical role in understanding the
technology from the perspective of the user [40].
Nevertheless, few studies have explored the usability of
DApps systematically. Most of the research on
decentralized exchanges is focused not on the usability to
users [41] but on technical implementations [9, 42, 43] or
legal regulations [44]. Some studies mention that usability
remains a key research topic for the success of blockchain
technology [67, 68, 69]. They emphasize that most
blockchain usability research provide solutions for
developers and not for end users. For example, Decker and
Wattenhofer [70] proposed auditing software to improve
the usefulness of bitcoin exchanges, and Di Battista et al.
[71] proposed a system for visually analyzing bitcoin flow
on the blockchain. For DApps to be operated actively, it is
necessary to identify and solve their problems
systematically by evaluating usability from the user
perspective.
This study aimed to understand UX with a decentralized
exchange—a type of DApp—to identify the usability
problems hindering the use of DApps. Decentralized
exchanges facilitate the exchange of the cryptocurrencies
utilized by most DApps. In addition, because the
cryptocurrency transaction process is similar to the
cryptocurrency wallet functions used by most DApps and
transactions without intermediaries, decentralized
exchanges are expected to have similar user experiences as
other DApps. Therefore, it is one of the DApps that should
be primarily researched.
IV. METHOD
In this study, a usability evaluation was conducted on the
KDEX mobile application, a decentralized exchange (Fig.
1), which was launched in Korea in 2018. In most
decentralized exchanges, real-time trading is difficult
because of the time delay in recording transactions on the
blockchain. To overcome this limitation, KDEX applies a
“ready-pending” system. Ready-pending supports the next
transaction by admitting the pending transaction that has
been processed but has not yet been recorded on the
blockchain as completed.
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Figure 1. Screenshots showing the main, transaction history, and
cryptocurrency wallet screens of KDEX.
The usability problems of KDEX were identified through
two methods: heuristic evaluation and user testing (Fig. 2).
To conduct the two evaluations effectively, a preliminary
survey was conducted before the heuristic evaluation, and a
pilot test was conducted before user testing. In the
preliminary survey, the main tasks performed in
cryptocurrency exchanges were listed. Based on the derived
tasks, experts performed a heuristic evaluation to
understand the function and task procedure of the
application. Subsequently, the experimental design was
modified to conduct user testing in the pilot test efficiently.
Finally, user testing was conducted for users with no
experience in using cryptocurrency exchanges. The
identified usability problems were classified and analyzed
based on the tasks.
A.
HEURISTIC EVALUATION
Heuristic evaluation is a usability engineering approach
proposed by Nielsen and Molich [45]. It is used to identify
usability problems in the user interfaces of web or mobile
applications. Usability experts conduct the evaluation based
on predetermined evaluation criteria [46, 47]. There is a gap
between the expert and the perspective of the actual user,
and the results are highly dependent on the skill level of the
experts. However, it is useful for evaluating systems
because it is easy and quick to apply, and it incurs a
reasonable cost [45, 47]. The ten heuristic evaluation
criteria used in this study were adopted from [48]. They are
visibility of system status; match between the system and
the real world; user control and freedom; consistency and
standards; error prevention; recognition rather than recall;
flexibility and efficiency of use; aesthetically pleasing and
minimalist design; help users to recognize, diagnose, and
recover from errors; and help and documentation.
The number of experts participating in a heuristic
evaluation has a significant effect on the results. One expert
is expected to identify about 35% of the problems [49]. The
larger the number of evaluators, the greater is the number of
problems that can be identified. The most cost-effective
number of experts is between three and five. It is expected
that 60–75% of usability problems can be identified via
evaluation using only three to five experts [49].
FIGURE 2. Process of the study.
Four experts of both UX and blockchain technology
performed a heuristic evaluation. The average experience of
the evaluators was five years. The experts were proficient
in UX and HCI, and they had sufficient knowledge of the
technical principles and applications of blockchain
technology. Prior to the heuristic evaluation, a preliminary
survey was conducted to derive the main functions of
cryptocurrency exchanges. As a result, six tasks were
derived (Table II). The heuristic evaluation was conducted
over a five-day period; at this time, each expert performed
the six tasks in KDEX and recorded the problems identified.
Following the completion of the evaluation, all evaluators
checked and shared the identified usability problems.
TABLE II
List of tasks identified for evaluation.
Task
No.
Task
Explanation
1
Sign up and
login
Sign up as a member and log in to the KDEX
mobile application
2
User
authentication
Complete the user authentication process for
transactions and deposit
3
Deposit
Complete the user authentication process for
transactions and deposit a certain amount of
cash into the application
4
Check the
chart
Check the cryptocurrency chart to view trends
in trading amounts, volumes, etc.
5
Trade
Buy and sell cryptocurrency
6
Check assets
Check the type and amount of assets
B.
USER TESTING
Although a heuristic evaluation has the advantages of being
fast and highly affordable, it derives several minor
problems that do not significantly affect user performance,
which are called false positives [47, 49, 51]. Therefore, in
this study, user testing was conducted to identify usability
problems that have a serious effect on user performance.
Although user testing requires a considerable amount of
time and cost, it can identify problems that substantially
affect performance and measure user satisfaction when
interacting with an application. From previous studies, it is
known that usability problems are efficiently identified by
combining heuristic evaluation and user testing [50].
A total of 23 users (14 male, 9 female) participated in the
user testing. All users had no prior experience in using
cryptocurrency exchanges. Their average age was 24.9
years (SD 4 years; minimum = 20 years and maximum = 35
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years), and all participants were familiar with using mobile
applications without physical or cognitive difficulties.
Before the testing, a training session was held to ensure
that each participant fully understood the purpose and
process of the experiment. Users were notified that KDEX
was a blockchain-based exchange; however, they were not
informed how blockchain technology is specifically applied.
It was observed from the pilot test that the participants who
did not have experience with certain tasks such as checking
the chart (task 4) and trading (task 5) focused on learning to
perform those tasks rather than on finding usability
problems. To prevent this, a stock exchange application
was used to train them in tasks 4 and 5. In addition, in the
cases of tasks 4 and 5, differences may occur between the
participants in the experiment depending on the type of
cryptocurrency being used. To minimize these differences,
participants were asked to perform tasks using only
Ethereum, which is considered an appropriate
cryptocurrency for experiments because it is trading at a
reasonable price of around $400, and it is one of the most
actively traded cryptocurrencies. Subsequently, participants
performed the six tasks as in the heuristic evaluation (Table
II).
The time taken to complete each task was measured, and
the success status was recorded. To determine the task
completion time, participants were asked to ring the bell
when they began each task and again when they considered
it to be complete, regardless of the actual success or failure
of the task. Although the entire process was videotaped
with their consent, the time when the experimenter and the
user determined that the task was complete may differ. By
ringing the bell, the experimenter could pinpoint when the
user actually believed that the task was completed. Upon
finishing each task, a usability score signifying the
convenience of using DApp while performing the task was
determined from an 11-point Likert scale (0: very
inconvenient, 10: very convenient).
As a long experimental time could affect the
concentration of the participants, the experiment time
allotted for each task needed to be limited. A pilot test
showed that when the task was performed without difficulty,
the task time did not exceed 3 min for all tasks. Further, the
participants in the pilot test could abandon the task if they
did not know how to perform the task. The abandoning time
did not exceed 10 min in any case. Therefore, in this study,
a task that required more than 10 min was considered a
failure. During the experiments, participants were allowed
to rest and resume when they wanted if they felt tired.
There were two types of task failures. The first was a
task that was not completed within 10 min (Type A failure).
The second was a task that was not properly completed but
was marked as complete by the participants (Type B
failure). At the end of each task, participants were
interviewed on the usability problems they encountered,
regardless of the task success. Because the completion of
the previous task affects the ability to proceed to the next
task, the remaining processes of the failed task were
completed by the experimenter. After completing each task,
the participants were interviewed to ascertain what kind of
usability difficulties they had encountered, regardless of
success or failure.
V. RESULTS
Table III lists the number of participants who failed and the
success rate for each task. A total of seven participants
succeeded in all tasks, which accounts for only 30% of the
total. Among the 16 participants who failed more than one
task, 10 failed in one task, five failed in two, and one failed
in three. All participants successfully completed tasks 1 and
6. The task with the lowest success rate was task 3, with
more than half the participants failing. In terms of failure
type, there were 17 participants for Type A failure and six
for Type B failure, thereby indicating a significantly higher
rate of Type A failure.
Fig. 3 shows the average task completion time for a
successful case and the average usability score for all
participants. Task 2 required the most task completion time,
whereas task 6 required the least time for successful cases.
In task 3, seven participants did not complete the task
within 10 mins, whereas 11 successful participants
completed it in approximately 4 min. The average usability
score was highest for task 1, and lowest for task 2.
TABLE III
Number of participants per task failure type.
Type A
Type B
Total
Success rate
Task 1
100%
Task 2
5
5
78.3%
Task 3
7
5
12
47.8%
Task 4
1
1
2
91.3%
Task 5
4
4
82.6%
Task 6
100%
Total
17
6
23
Figure 3. Average task time and usability score for each task.
Table IV lists the results of classifying the usability
problems by task type. A total of 25 problems were found
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from the heuristic evaluation, and 13 problems were found
from user testing. Among them, 10 problems were
identified in both the heuristic evaluation and the user
testing. In addition to the 10 overlapping problems, 15 out
of the 28 problems were found only in the heuristic
evaluation. Those included minor problems such as the
intuitiveness of the icon and the color of the letters. Three
problems derived from only the user testing were related to
task 3.
TABLE IV
Derived usability problems.
Heuristic
Both
User testing
Task 1
Color of the sign-up button is similar
to the background
Task 2
Color of some pictures that have no
function changes when the user
touches them
Explanation and design during the
deposit process is very confusing
Insufficient guidance for authentication
process
Task 3
Pop-up notification messages have a
limited length, which makes it
impossible for the user to identify the
scenario
Even if the user can understand
notifications by entering the
notification menu, the notification
indicator does not disappear. It only
disappears when the user touches the
“all notifications” list
The user must memorize deposit account
information as there is no copy function
There is no feedback for an incorrect
deposit amount
The user cannot find the “deposit”
button
The user misunderstands the deposit
request as deposit completion
No information is provided about the
time gap between deposit and remittance
Task 4
There is no way to access the chart
screen except from the transaction
screen
Buttons to change the chart options
are not intuitive
Letters are covering the chart
Icons without functions are presented
in the chart setting and transaction
history menu
When the sort button changes the item
order, it does not indicate which criterion
is selected
No descriptions are provided for charts
or terms
Task 5
No explanation is provided for the
presence of two transaction histories
for one transaction
The icon to set the transaction history
period is not intuitive
Even if the user does not have the
cryptocurrency, they can proceed to
the next step and the transaction
disappears when they complete the
transaction procedure
The menu bar disappears only on
buy/sell screens
Inconsistent colors in letters, charts,
etc. on buy/sell screens
Some cryptocurrencies have different
buy/sell fees
To trade a specific cryptocurrency, the
user needs to create a wallet for that
cryptocurrency. Even if the user does not
have the wallet, they can proceed to the
next step, and the transaction disappears
when they complete the transaction
procedure.
No information is provided about the
deposit amount until the user attempts to
make a deposit below the minimum
amount
No feedback for buy or sell orders
No descriptions for icons or changes
presented during the transaction
Task 6
No visualization of the area division
and touchable parts between
categories in the same row
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VOLUME XX, 2017 9
VI. MAJOR HURDLES TO BLOCKCHAIN TECHNOLOGY
INTRODUCTION
Introducing blockchain technology to a cryptocurrency
exchange caused a considerable number of problems. Three
types of problems were identified in this study: the
cryptocurrency wallet requirement, time gap between the
occurrence and recording of transactions, and transaction
fees.
A.
CRYPTOCURRENCY WALLET REQUIREMENT
In task 5, several participants failed because they did not
know that the cryptocurrency wallet must be created before
progressing to any transaction. To understand the problems
related to the cryptocurrency wallet, it is necessary to know
how to use cryptocurrency wallets. A cryptocurrency wallet
is a virtual object that refers to the digital credentials of the
currency holdings [50]. Unlike wallets used in everyday life,
which actually store fiat money, identification cards, etc.,
cryptocurrency wallets serve to store and manage private
keys for signing transaction data recorded on the
blockchain. Separate cryptocurrency wallets are required
for each cryptocurrency type; only Bitcoin can be stored in
the Bitcoin wallet, only Ethereum can be stored in the
Ethereum wallet, and so on. To hold or trade a specific type
of cryptocurrency, a wallet must first be created for that
cryptocurrency. Because the process of creating a wallet
before a transaction is unfamiliar to many users, relevant
information should be provided. Most DApps provide a
cryptocurrency wallet because they utilize cryptocurrency
and tokens. Therefore, improving the usability of
cryptocurrency wallets is essential to ensure excellent UX
in DApps.
B.
TIME GAP BETWEEN OCCURRENCE AND
RECORDING OF TRANSACTIONS
The second problem is caused by the time gap between the
occurrence of a transaction and the recording of the
transaction in a blockchain. In KDEX, all transactions are
recorded in the blockchain; however, the problem is that the
occurrence time and recording time of transactions differ
[38]. To prevent double-spending, transactions remain in
the waiting state without transmitting cryptocurrency until
the next block is created. The time between transaction
occurrence and confirmation depends on the creation time
of the block and the number of transactions waiting to be
recorded. This time gap is significantly longer than that of
existing financial transactions that users normally encounter
in a centralized system, such as in a bank [26]. In the case
of Bitcoin, it takes an average of 10 min to create a new
block [12]. In other words, when using the Bitcoin
blockchain, it takes 10 min for a transaction to be recorded.
Some networks utilize a transaction-priority mechanism to
provide an option to reduce recording time by paying
higher fees [19, 53, 54].
As a result of the interview for task 3, it was found that
the participants misunderstood the deposit process because
they did not receive information about the time gap after
depositing money in the cryptocurrency wallet. They
assumed that they had made a mistake in the remittance
process or that there was an error in the system during the
time the transaction was reflected in the cryptocurrency
wallet. In task 5, there was a problem of doubly generated
histories for one transaction. This was not encountered
during the user testing owing to insufficient experiment
time. KDEX provides a “ready-pending” function to
overcome inconsistent and long waiting periods until the
completion of a transaction. To enable the next transaction
to occur immediately after the previous one, it assumes the
transaction is completed before it is recorded on the
blockchain. Therefore, in the transaction history, there are
two records of one transaction: first, when the transaction
occurs, and second, when it is recorded on the blockchain.
It takes up to several minutes between the two events.
Because users cannot receive guidance about the ready-
pending function anywhere during the task, they may
believe this to be a double transaction.
C.
TRANSACTION FEES
There was a problem related to the transaction fee, which
was found only in the heuristic evaluation. In KDEX, the
transaction fee varies depending on the payment method,
even if a user purchases the same type of cryptocurrency
(Fig. 4). There are two types of fees: the platform fee and
the blockchain network fee. The platform fee is the fee for
using the KDEX platform, and the blockchain network fee
is that for recording a transaction on the blockchain. When
a buyer performs a transaction that pays in fiat money, both
the buyer and the seller must pay a platform fee equal to
0.1% of the transaction amount. At this time, the seller must
additionally pay the blockchain network fee in fiat money.
If the buyer purchases another cryptocurrency with a
specific cryptocurrency that they own, a platform fee equal
to 0.2% of the transaction amount and a blockchain
network fee in fiat money are charged to both the buyer and
the seller. This policy on fees is not only difficult to
understand, but the criteria for setting the fee amount and
the means of payment are ambiguous. Users who are
unfamiliar with blockchain technology might not
understand the blockchain network fees, which do not exist
in a centralized system. The results of this study show that
the DApp design, which is considered reasonable by
technology developers, can be severely problematic for
users. This indicates that DApp providers are not
sufficiently considering the changes that blockchain
introduces. It is expected that usability problems caused by
introducing blockchain can be solved by accurately
accounting for changes and systematically analyzing their
effects on task performance.
VII. DESIGN CONSIDERATIONS FOR DAPPS
The majority of DApps developers focus on functionality,
maintenance, and stability [29]. However, the results of this
study and several recent studies suggest that developers
need to invest more effort in understanding UX.
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VOLUME XX, 2017 9
Figure 4. Fees incurred in cryptocurrency transactions.
A. ADOPT MENTAL MODEL FROM SIMILAR SYSTEMS
A mental model is an intuitive understanding of a system’s
functionality in terms of its internal structure and processes
[55, 56, 57]. It helps users interpret the actions of the
system and predict the outcome [56, 58]. Difficulty in
forming a suitable mental model for a system is a primary
cause of usability problems [59]. Therefore, it is necessary
to establish an appropriate mental model to eliminate
difficulties in the use of DApps. When performing tasks,
the majority of participants assumed that KDEX would
have the structure and operation method similar to bank
applications. However, because KDEX was designed to
work differently from bank applications, users needed to
build a new mental model. Some participants stated that
this was not difficult once they determined how it works;
however, it is difficult to understand initially.
The cryptocurrency exchange usage procedure is similar
to that of some existing systems; the cryptocurrency trading
function is similar to that of a stock exchange. Further, a
cryptocurrency wallet is similar to a bank account in that it
supports the management and transfer of cryptocurrencies
(Fig. 5). However, KDEX does not use a mental model
similar to any existing system. For example, a wallet
address that acts similar to a bank account number is long
and has no rules, which makes it difficult for general users
to remember. In addition, most cryptocurrency wallets
provide functions such as “receive” and “send.” “Receive”
simply means sharing the wallet address. General users,
who have a mental model for using bank accounts, may be
confused when they first encounter these terms. Numerous
usability problems in tasks 3 and 5, related to
cryptocurrency wallets and transaction fees, respectively,
were caused by an inaccurate mental model. As most users
have a mental model for similar systems, it is recommended
that a mental model that users already have or are familiar
with be implemented. By utilizing an existing mental model,
the effort invested by the user to build a new mental model
can be minimized, which can contribute to lowering the
entry barrier to blockchain technology.
Figure 5. Differences between a bank account and a cryptocurrency
wallet.
B. DELIVER THE VALUE OF DAPPS
DApp developers attempt to add several advantages when
introducing a blockchain into the system. KDEX can almost
completely block external attacks, which are the greatest
threat to existing centralized exchanges. Unlike centralized
exchanges, which require the exchange to fiat money and
withdrawal to a bank account to hold the traded
cryptocurrency, cryptocurrency possession is immediately
granted to the buyer in KDEX. The ownership of the
cryptocurrency is confirmed immediately after the
transaction is recorded on the blockchain. Further, KDEX
has high security and transparency as all transactions are
recorded on the blockchain. However, none of the
participants commented on these advantages, which
indicates that the DApp failed to deliver its value to its
users.
For a DApp to survive in the market, it is important to
effectively deliver the value of the application to users [26,
29]. The more attractive the technology, the more likely it
is that technology experts will focus on the benefits of the
technology and disregard the users’ actual acceptance of the
value of the technology [59]. Blockchain technology
remains an unfamiliar concept to the majority of users,
thereby making it difficult for users to grasp its intrinsic
value. Rather than explaining the technical value of
blockchain technology to general users, it is necessary to
design it such that users can intuitively find advantages
while using the DApp. It is possible to deliver the value of a
DApp effectively by ensuring good usability and interaction
experiences [61]. Poor interaction experiences lead to users
utilizing only the features they can accept, which deprives
them of the opportunity to experience the value of emerging
technology [60]. Therefore, developers should contemplate
approaches to provide good usability when introducing
blockchain applications. With excellent usability, users can
easily grasp the value of DApps.
Ⅷ. CONCLUSION
This study conducted usability testing on a decentralized
exchange to investigate the cause of blockchain technology
not being accepted by users despite its value. In addition to
the general usability problems that appear in mobile
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VOLUME XX, 2017 9
applications, the major problems that appeared when
introducing blockchain to cryptocurrency exchanges were
identified. Many researchers emphasize the need for a user-
centered approach whenever new technologies emerge;
however, the results of this study show that this is not being
applied in the industry. Based on our findings, two primary
strategies are suggested for developers to ensure the
acceptance of blockchain technology: adopting a mental
model from similar systems, and effectively delivering the
value of the technology through good usability.
This study conducted an experiment with users in their
20–30s, who are very familiar with using mobile
applications. In addition, because the experiment was
conducted only on decentralized exchanges—one of the
DApps in the financial field—it is difficult to reflect the
characteristics that can appear in various fields where
blockchain is actively used accurately, such as in SNS and
medical service. Nevertheless, this study is significant in
that it proposes a systematic approach for the successful
introduction of emerging technologies.
Blockchain technology can be used for a variety of
applications in a wide range of fields. More meaningful
insights can be obtained by comprehensively analyzing
user-centered studies on DApps in various fields as well as
on other emerging technologies.
ACKNOWLEDGMENT
This research was supported by the National Research
Foundation of Korea (NRF) grant funded by the Korea
government (MSIP) (No. NRF-2019R1A2C1086366), and
by the Ministry of Science and ICT (MSIT), Korea, under
the Information Technology Research Center (ITRC)
support program (IITP-2018-0-01441) supervised by the
Institute for Information & communications Technology
Promotion (IITP).
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