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Consistency in Web Design from a User Perspective

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Within Human-Computer Interaction, it has long been speculated that inconsistency impedes the user experience. However, defining and categorising consistency has been shown to be a challenging task. Several studies on the subject have categorised consistency with mixed perspectives of the system, its developer, and its user. The present thesis considers only the user perspective, and categorises consistency into Perceptual, Semantic, and Procedural consistency. 21 subjects, with moderate experience in using the web, participated in an experiment designed to explore the effect inconsistency might have on usability. In order to test both main and interaction effects between the three proposed consistencies, the experiment was based on a full 2 × 2 × 2 factorial design for repeated measures. The participants’ task was to use eight partly different versions of a mock-up web shop in which a subject selection drop-down menu was experimentally manipulated. Multiple Analysis of Covariance revealed that Perceptual and Procedural inconsistency affected user performance negatively. It also indicated that inhibitory interaction effects occurred between some of the (in)consistencies. The results have important implications for web developers in designing usable applications. By adapting a user perspective, they can aid users to avoid performing faulty actions.
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Bachelor’s Thesis
15 credits
Consistency in Web Design from a User Perspective
Konsekvent webbdesign utifr˚an ett anv¨andarperspektiv
Anton Axelsson
m09p0891@student.mah.se
Exam: Bachelor of Science 180 credits
Subject area: Computer Science
Programme: Information Architecture
Date of final seminar: 2012-09-20
Examiner: Bengt Nilsson
Supervisor: oran Hagert
Abstract
Within Human-Computer Interaction, it has long been speculated that in-
consistency impedes the user experience. However, defining and categor-
ising consistency has been shown to be a challenging task. Several studies
on the subject have categorised consistency with mixed perspectives of the
system, its developer, and its user. The present thesis considers only the
user perspective, and categorises consistency into Perceptual, Semantic,
and Procedural consistency. 21 sub jects, with moderate experience in us-
ing the web, participated in an experiment designed to explore the effect
inconsistency might have on usability. In order to test both main and in-
teraction effects between the three proposed consistencies, the experiment
was based on a full 2×2×2factorial design for repeated measures. The
participants’ task was to use eight partly different versions of a mock-up
web shop in which a subject selection drop-down menu was experimentally
manipulated. Multiple Analysis of Covariance revealed that Perceptual
and Procedural inconsistency affected user performance negatively. It also
indicated that inhibitory interaction effects occurred between some of the
(in)consistencies. The results have important implications for web de-
velopers in designing usable applications. By adapting a user perspective,
they can aid users to avoid performing faulty actions.
Keywords: consistency, usability, web design, HCI, user perspective
Sammanfattning
Inom människa-datorinteraktion har det länge spekulerats huruvida in-
konsekvent design påverkar användarupplevelsen. Att definiera och kate-
gorisera olika typer av konsekvens har visat sig svårt. Flera studier på
området har kategoriserat typer av inkonsekvens med blandade perspek-
tiv av såväl systemet, dess utvecklare samt dess användare. Denna uppsats
sätter användarens perspektiv i fokus och kategoriserar typer av inkon-
sekvens i perceptuell, semantisk och procedurell konsekvens. 21 personer,
med måttlig erfarenhet av att bruka nätet, deltog i ett experiment utfor-
mat att utforska effekterna av inkonsekvent design på användbarhet. För
att pröva såväl huvud- som interaktionseffekter baserades experimentet
på en fullständig 2×2×2faktordesign för upprepade mätningar. Del-
tagarnas uppgift var att använda åtta prototyper av en webbutik där en
dropdownmeny för ämnesval utsattes för experimentell manipulation. En
trevägs variansanalys med kovariat visade att perceptuellt och procedu-
rellt inkonsekvent design påverkade användarupplevelsen negativt. Resul-
taten pekade också på att hämmande interaktionseffekter uppstod mellan
vissa av de tre inkonsekvenserna. Resultaten ger viktiga implikationer för
webbutvecklare när de skall utveckla användbara applikationer. Genom
ett användarperspektiv kan utvecklare hjälpa användare att undvika fel-
aktiga handlingar.
Nyckelord: konsekvens, användbarhet, webbdesign, MDI, användarper-
spektiv
Contents
1 Introduction 1
1.1 Previous Research on Consistency . . . . . . . . . . . . . . . . . 1
1.2 Redifining Consistency within HCI . . . . . . . . . . . . . . . . . 4
1.3 Purpose and Expected Outcomes . . . . . . . . . . . . . . . . . . 6
2 Methods 9
2.1 Participants.............................. 9
2.2 Material................................ 9
2.3 Design................................. 11
2.4 Procedure............................... 12
2.5 Measurements............................. 13
3 Results 15
3.1 Sample................................. 15
3.2 Handling Covariance . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.3 UserSatisfaction ........................... 17
3.4 UserError............................... 18
3.5 UserEciency ............................ 19
4 Discussion 21
4.1 Implications.............................. 21
4.2 Limitations .............................. 22
4.3 FurtherResearch........................... 23
4.4 Conclusions.............................. 24
A Baseline Choice Selections 29
B Variations of Inconsistency in Subject System 30
C Task Compendium 33
D Consent Form 44
1 Introduction
It has long been debated whether or not consistency is an important factor
of usability within Human-Computer Interaction (HCI). Shneiderman (1992)
claimed consistency to be the primary concern when putting forth his heur-
istic eight golden rules of dialogue design. Grudin (1989) argued antithetically
against this by pointing out instances where consistency might counteract usab-
ility. Reisner (1981) highlighted early on that there is very little agreement as to
what consistency actually is. Many have since tried to approach an explanation
by singling out and categorising different types of consistencies (e.g., Grudin,
1989; Kellogg, 1987; Tanaka, Eberts & Salvendy, 1991).
Findings from studies and experiments on the subject have since been brought
forward, disclosing mixed results (e.g., Adamson, 1996; AlTaboli & Abou-Zeid,
2007; Kellogg, 1987; Mendel & Pak, 2009; Ozok & Salvendy, 2000; Satzinger,
1998). Therefore, the answer as to what consistency within HCI should entail
remains elusive.
The aim of the present study is to explore whether consistency affects usab-
ility, by an experiment testing the main effects and interactions of Perceptual,
Semantic, and Procedural consistency. In contrast to previous research, we ex-
plicitly define consistency entirely from the user’s, rather than the developer’s
or system’s, point of view.
1.1 Previous Research on Consistency
1.1.1 Difficulties in Defining Consistency
Attempts at capturing the essence of consistency were made already in the times
of terminal based operating systems and applications. The focus of research was
initially aimed at consistency in command language (e.g., Barnard, Hammond,
Morton, Long & Clark, 1981; Payne & Green, 1986; Reisner, 1981).
At the ACM CHI’88 conference in Washington, a workshop was held with
15 usability experts aiming to agree on a joint definition of consistency for HCI
(Nielsen, 1989). An agreement was never met and, therefore, the term still has
not been given an adequate definition. Instead, it has been, and still is, used
implicitly under its conventional meaning.
Generally, it is claimed of consistency within HCI, that it allows users to
reason analogically and thereby predict actions within novel tasks (Blake, 1986;
Mayhew, 1992). Others reason that consistency means that similar actions lead
to similar results (Wolf, 1989; see also Shneiderman, 1992; Wiecha, Bennett,
Boies & Gould, 1990).
Kellogg (1989) argued that consistency is meaningless on its own, thus ren-
dering a guideline with consistency as an independent goal meaningless. Con-
stantine and Lockwood (1999) made a similar claim saying that striving for
consistency for its own sake might lead to “consistently bad solutions” (p. 62).
Conversely, it has been claimed that there are instances where inconsisten-
cies are desirable. Shneiderman (1992) mentions for example how passwords
should not be echoed to users and that delete operations should result in a con-
firmatory prompt, also pointing out that these types of inconsistencies should
be kept at a minimum.
With all these separate views on consistency it is no surprise that Smith, Irby,
1
Kimball, Verplank and Harslem (1982) deemed it the most difficult characteristic
to attain within system development.
1.1.2 Frameworks for Consistency
Grudin (1989) requested a new way of viewing consistency within HCI. He put
forth an antithetical view that consistency of a user interface is an unwork-
able concept and said it to lead designers astray, disguising good design as an
interface property.
After the ACM CHI’88 workshop he came to the conclusion that work on
defining consistency should be restarted. As a way of starting anew, he proposed
three categories of consistency: (1) internal, (2) external, and (3) analogue. The
internal category comprises consistencies within an application (or web site), the
external category comprises consistencies between applications or platforms, and
the analogue category comprises consistencies with conceptual metaphors, such
as the desktop metaphor (Smith et al., 1982). He also hinted at a fourth
category, (4) veridical, which would be an interface fully consistent with its
system’s design (rather than the user’s needs).
Subsequent to the theoretical work of Grudin (1989), attempts at defining
consistency was abandoned and instead work was aimed at finding types and
categories of consistencies.
Building on Moran’s (1981) ideas of interface levels, Kellogg (1987) con-
structed a framework consisting of (1) conceptual, (2) communicational, and
(3) physical consistency, which were all either internal or external. Conceptual
consistency concerned correspondence to metaphor and mapping between user
and system tasks. Communicational consistency concerned interaction between
user and system, and physical consistency was related to screen layout.
Tanaka et al. (1991) distinguished between two types of consistencies: (1)
cognitive and (2) display. Cognitive consistency is characterised by consistency
in user knowledge, whilst display consistency is defined as consistency in screen
layout.
Somberg (2000) argued that too much focus within development of interface
standards had been aimed at the look and feel of systems. A new approach called
functional user interface standards, based on object-oriented programming, was
proposed to deal with task performance, thereby facilitating what he called
procedural consistency.
1.1.3 Measuring Usability
In order to measure the usability of a system, usability metrics are used. Two
categories of metrics are normally used in experiments on consistency within
HCI: (1) performance metrics and (2) self-reported metrics. Performance met-
rics can be measured through the time it takes to complete a task (time-on-task),
number of errors made, or the number of clicks made (click rate), whereas self-
reported metrics are measures reported by users themselves, such as how they
rate an application or how difficult they found a task to perform (Tullis &
Albert, 2008).
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1.1.4 Preceding Experiments
Adamson (1996), Ozok and Salvendy (2000), and AlTaboli and Abou-Zeid
(2007) found physical inconsistency to increase user errors. AlTaboli and Abou-
Zeid (2007) also found evidence that it affects user satisfaction.
Adamson (1996) found indications that communicational inconsistencies af-
fect user performance and satisfaction, which Ozok and Salvendy (2000) did
not.
Kellogg (1987) found that conceptual inconsistencies affected both user per-
formance and satisfaction, whilst Ozok and Salvendy (2000) found no such evid-
ence.
Mendel and Pak (2009) pointed out the fact that the mixed, and sometimes
even detrimental, results of all these experiments may lie in the manipulation of
task difficulty. Adamson (1996) used a combination of radio buttons and drop
down menus to create his inconsistencies. It is both interesting and surprising
that he found evidence for effects on user performance and satisfaction for such
a simple experiment. One factor might be that nearly 30 percent of his subjects
had very little experience of using graphical user interfaces. Ozok and Salvendy
(2000), on the other hand, had participants more experienced with user inter-
faces, which could account for the diametrically opposite results of Adamson
(1996) with regard to communicational inconsistency.
Another possible explanation for the mixed results of these experiments is
that experimenters might be tainted by their own interpretations of what is
consistent and what is not. Satzinger (1998) carried out a study on consistency
of conceptual models. He found no evidence that his manipulation affected
user performance or satisfaction. He did, however, find indications that “more
accurate mental models might be developed when conceptual models are incon-
sistent (p. 11, original emphasis). Participants in his experiment were asked to
carry out tasks in two separate systems. All participants used a system called
NUCLEUS as a first system. Half of the participants used a second system con-
sistent in action grammar to NUCLEUS and the other half used a second system
inconsistent in action grammar to NUCLEUS. For example, in the inconsistent
version the action ‘Delete’ was called ‘Erase’. The question is whether the terms
‘Delete’ and ‘Erase’ are really conceptually inconsistent from a user’s point of
view. Perceptually they look different, but semantically they mean the same
thing, and in the two systems they resulted in the same action. This would
make them conceptually consistent. If, on the other hand, the two terms had
been used within the same system with the same outcomes then this could be
perceived as inconsistent, and would thereby possibly confuse users.
1.1.5 Consistency from the Developer’s Perspective
The current view on consistency seems to be founded in a developer’s perspect-
ive. Satzinger’s (1998) study on conceptual consistency illustrates this, but the
most prominent example is one of Grudin’s (1989) arguments of when incon-
sistencies are desirable. Although acknowledging the fact that what a developer
(or designer) might consider consistent might as well be inconsistent in the eyes
of the user, he seems to overlook this in his example.
The example is one from early word processors, where a user selects a phrase
in order to italicise it through a menu. The next time the user selects a phrase
3
and enters the same menu, the italic option is preselected. Thus, the system con-
sistently preselects previously used options to ease word processing. However,
when the user returns to the menu after copying a selection to the clipboard,
this time the paste option is preselected. According to Grudin (1989), this is
a facilitating inconsistency in the word processor. But, this example is only
inconsistent when considered from the developers reasoning when building this
feature. If we instead look at it from a user’s perspective, this feature is consist-
ently facilitating the user with what action the user most probably would like
to perform next.
Thus, it is proposed that we shift our focus from a developer’s, and even
a system’s, perspective to one which only considers the user’s perspective with
regard to consistency in HCI.
1.2 Redifining Consistency within HCI
In recent years outspoken professional web developers have claimed consistency
to bear no importance, at least with regard to web usability (37signals, 2006;
Hurst, 2004). Instead they advocate that user needs should be prioritised over
interface consistency. Hurst coined this way of reasoning intelligent inconsist-
ency.
The shift of concern regarding consistency from Shneiderman (1992) saying
its vital, via Grudin (1989) calling it misleading, to Hurst (2004) deeming it is
insignificant, is possibly due to the fact that consistency has become easy to
take for granted within application development. This because it has become
easier to achieve over the years thanks to concepts such as object-oriented pro-
gramming and graphical user interface libraries. These ensure reuse of code
and graphical elements. The definitions of HTML standards do the same for
web site applications, as do the multitude of usability guidelines which many
developers and designers adhere to.
This is possibly why Hurst (2004) considers consistency a non-issue when it
comes to web site design. However, it does not alter the necessity of consistency
from a user’s point of view. It might be somewhat easier to achieve, thanks
to a tremendous work of standardising the development of applications, but
consistency is still of fundamental importance. It is therefore vital to come to
a conclusion as to what consistency really is and decide on a definition of what
it means within HCI.
1.2.1 Etymology of ‘Consistency’
The term ‘consistency’ is derived from the Latin word consistere whose literal
meaning is “to stand still”. Encyclopedia Britannica (2012) defines ‘consistent’
as “not having or showing any apparent conflict”, whilst The Free Dictionary
(2012) defines the term as “[r]eliability or uniformity of successive results or
events”. Thereby, consistency is purely relational and concerns perceived uni-
formity between two or more occurrences. Related words include ‘coherence’,
‘familiarity’, and ‘regularity’.
The opposite of consistency is inconsistency, which entails that irregular
patterns emerge when two or more occurrences are compared, between which
we would expect regularities. This, as we shall see, can be crucial for decision
making.
4
1.2.2 Cognition and Consistency
In a fire’s seemingly haphazard behaviour there are regular patterns which an
experienced firefighter can interpret. In order to explain the inner workings
of intuition, Klein (1999) referred to a particular case that illustrated how a
commander reacted on a gut feeling to flee when a fire did not act as anticip-
ated, and thereby he saved the lives of himself and of a group of several other
firefighters.
Tiny clues in the environment can be picked up by humans and other an-
imals. Regular patterns are subconsciously registered upon which decisions are
based. All species alive today are the product of their ancestors’ decisions.
By evolving in an environment with regularities, we have learned what to eat
and what to avoid. Poor decisions means being left out of the gene pool. The
survivors have thereby added refined skills of pattern recognition to succeeding
generations by making the right choices (Shermer, 2011).
We are dependent on our ability to recognise inconsistency for survival. We
recognise familiar patterns, or acknowledge disruption of patterns, and upon
this we base our decisions. Our innate ability to recognise inconsistency alerts
us also when interacting with computers, and the conventional view is that it
impedes usability.
1.2.3 Definition and Categorisation
As previously acknowledged, through the dictionary definitions, consistency is
a relational concept. It can be argued that it is therefore also a subjective,
observational phenomenon. In order to have consistency, you need an observer
who apperceives. Thus, in HCI, this implies that consistency of a web site can
never exist independently from its user’s experience and expectations; they are
intricately intertwined because consistency is founded in the user’s apperception.
With the view that consistency should be redefined from a user perspective,
the need for a new definition of consistency within HCI also arises. The following
definition will be used for this study:
Consistency is the user’s apperception of regularities within a sys-
tem, leading the user to actions in the task environment based on
previous experiences.
This leaves Grudin’s categories somewhat counterintuitive because they are
based on a claimed consistency’s origin, and therefore bears little relation to
the user. The veridical category leaves the user completely out of the picture,
whilst the analogue category is unreliable because it is dependent on knowledge
transfer. Studies have shown that there are no guarantees that the knowledge
transfer will occur on its own, without connections being explicitly pointed out
to the learner (or user; Gick & Holyoak, 1980 in Barnett & Ceci, 2002). Internal
and external consistencies can be somewhat useful as a means of discussing
whether an argued consistency is derived from, for example, industry standards
(external) or company guidelines (internal).
Based on previous work on categorising and developing frameworks for con-
sistency (e.g., Grudin, 1989; Kellogg, 1987; Tanaka et al., 1991), we propose
a new categorisation, redefined from a user’s perspective, taking cognition into
5
consideration. This is motivated by the subjective nature of consistency, as dis-
cussed in Section 1.2.2. Previous categories mixed features of the system with
the user’s cognitive abilities. These must be kept apart. The three redefined
categories proposed are Perceptual,Semantic, and Procedural consistencies.
Perceptual Consistency
Perceptual consistency has to do with what we perceive when interacting with,
for instance, a web site. Most commonly it will be through the visual perception,
but can of course be auditory for visually impaired. This includes the use of
colours and graphical elements, adhesion to the gestalt principles (e.g., Kanizsa,
1979), and so forth. For example, the use of the same fonts and font sizes in
a text in a paragraph facilitates reading. Perceptual consistency is similar to
Kellogg’s (1987) physical consistency, although with a shift in focus from screen
layout to the user’s perception of the system.
Semantic Consistency
Semantic consistency is derived from our semantic memory for facts and words.
It has to do with consistent use of symbols and icons in correct context; if what
has been perceived is consistent in meaning so that the correct action can be
taken in the next step. When a system is semantically consistent it facilitates
the user’s conceptual model (Foley & van Dam, 1982). The term “semantic”
is here used in its traditional meaning, but with the amendment of including
the position of objects and symbols. In interaction design, the placement of
an object is as important as its appearance for inferring the object’s purpose
in the same way that words can have different meanings in different contexts.
Examples of Semantic consistency include that all anchors should be coloured
blue and underlined, or that submit buttons should appear in the same place
in all forms throughout a web site.
Procedural Consistency
Procedural consistency has to do with whether action types and sequences ne-
cessary to achieve a goal are consistent or not. For example, all drop-down
menus need one click to reveal options, and another click to choose one of the
revealed options. Procedural consistency is similar to Kellogg’s (1987) commu-
nicational consistency with the alteration that it only takes the user’s actions
into account when interacting with the system. In the present model, the sys-
tem part of the communication is considered under Perceptual consistency, in
how the user perceives feedback from the system.
1.3 Purpose and Expected Outcomes
The area of consistency within HCI lacks in clear theories. As mentioned earlier,
the conventional view is that inconsistency impedes usability, but (in)consistency
has previously only been loosely defined. Our purpose is to explore whether or
not Perceptual, Semantic, and Procedural inconsistencies affect user perform-
ance and satisfaction, and if there are any interaction effects when combining
these inconsistencies. Empirical results on the relationships between different
kinds of inconsistency, based on the user’s point of view, is expected to contrib-
ute to the development of theory of consistency within HCI. Adapting a user’s
6
perspective justifies the need for conducting a behavioural experiment.
Drawing on previous research (Adamson, 1996; AlTaboli & Abou-Zeid,
2007; Kellogg, 1987; Ozok & Salvendy, 2000) it is expected to find main
effects on both user performance and user satisfaction from the three kinds
of inconsistencies. Importantly, it is unusual to consider interaction effects in
studies of inconsistency, but drawing on previous results, any interaction effects
between the three inconsistencies are expected to be cumulative, leading to an
amplified decrease in user performance, as well as, satisfaction.
7
2 Methods
2.1 Participants
A convenience sample of 21 participants was recruited for the experiment (7
women, 14 men; Mage = 31 years, SD = 7.04 years). The minimum computer
experience was 10 years. Of the 21 participants, 8 had either begun or completed
a university degree in, or worked professionally within a computer related field.
On average, the participants reported spending 3.5 hours each day actively on
the Internet. They also reported having, on average, moderate experience (3
on a 4-point category scale) filling out forms on the web, as well as purchasing
products over the web.
2.2 Material
Data was collected in a computer lab at the Malmö School of Technology. Each
participant was assigned a computer, running Windows 8, and the assignments
were performed using eight Web site versions of a mock-up web shop running
in a Firefox (v14.0.1) browser. Each participant was also given a pen and an
assignment compendium, consisting of a cover page, an introduction, and eight
numbered tasks (an example compendium is enclosed in Appendix C).
2.2.1 Mock-Up Web Shop
The web shop was built using PHP, HTML5 and JavaScript (Figure 2.1b). The
back-end was running on an Apache server and utilised a MySQL database. All
user activity, key strokes and mouse clicks, was logged through JavaScript and
sent in the background through AJAX requests to the server.
Throughout the web shop, sequences of drop-down menus were used to select
categories and subcategories of options (see Figures in Appendix A & B).
Initially, in the consistent, or baseline, version of the web shop, only one drop-
down menu for subcategory selection was visible. Once an option was selected in
the visible drop-down menu, the next subcategory drop-down menu appeared.
This system of drop-down menus was used to select newsletter options, expiry
date for credit card payment, and subject categories in a contact form, in three
separate parts of the web shop.
The subject drop-down menu system (henceforth, subject system) in the
web shop’s contact page was subjected to experimental manipulation, whereas
the newsletter and expiry date selections were kept constant in the experiment.
The rationale behind this design was that inconsistency is relational, and may
thus only occur in relation to a baseline. Hence, in the present experiment the
drop-down menu system for selecting newsletter options and expiry date options
for credit card payment was used as the baseline.
All combinations of presence/absence of the three inconsistencies (Percep-
tual, Semantic, and Procedural) were used in a full 2×2×2factorial design
to alter the subject system on the contact page. This resulted in eight different
versions (W1-8) of the web shop, or rather, eight different versions of the subject
system on the contact page depicted in Figure 2.1c. The figures in Appendix
B depicts the manipulations of the subject system.
9
(a) Introductory demographics form. (b) Web shop mock-up.
(c) Contact page. (d) Post task evaluation.
Figure 2.1: Web site setup.
Web site 1 (W1) included none of the inconsistencies (Figure B.1). Thereby,
the subject system on the contact page was fully consistent with the baseline
newsletter and expiry date selection.
Web site 2 (W2) included Perceptual inconsistency in the subject system on
the contact page when compared to the baseline drop-down menus (Figure B.2).
In this version the subject system was replaced by buttons and radio buttons,
this in order to change its visual appearance compared to the baseline. A web
developer might argue that this would be a Semantic inconsistency, referring
to the semantic web. However, the manipulation is carried out from the user’s
perspective, in such a manner that it only affects how the subject system looks,
keeping the interaction of subject selection constant.
Web site 3 (W3) included Semantic inconsistency in the subject system
on the contact page when compared to the baseline drop-down menus (Figure
B.3). The drop-down menu system was kept. However, the drop-down element
was given the visual appearance of the baseline element label. Conversely, the
element labels were given the visual appearance of the baseline drop-down ele-
ment (see Figure B.1). In addition, the element label was placed to the right
of the drop-down element instead of above as in the baseline version. Thus, the
baseline semantics were interchanged; an orange frame and yellow background
with black text represented the drop-down element in the baseline, but here rep-
resented a label, whilst black text on white background represented the element
label in the baseline, but here represented the drop-down element.
Web site 4 (W4) included Procedural inconsistency in the subject system
10
on the contact page when compared to the baseline drop-down menus (Figure
B.4). The drop-down system was kept. However, when choosing a subject
subcategory in this version, the subsequent subcategory drop-down menu did
not appear automatically. Instead, the user had to click on an orange arrow
to the right of the subcategory in order to reveal the subsequent subcategory
drop-down menu. This obliged the user to carry out additional actions (pointing
and clicking) in the procedure of choosing the contact subject. This resulted
in an inconsistent procedure when choosing contact subject compared to the
baseline’s automatically appearing drop-down menus.
Web site 5 (W5) combined Perceptual and Semantic inconsistencies (Figure
B.5). Thereby, the subject selection drop-down menus on the contact page were
replaced by buttons and radio buttons, and also, an interchange of semantics
was carried out in a similar fashion of W3.
Web site 6 (W6) combined Semantic and Procedural inconsistencies (Figure
B.6). The exact interchange of semantics applied in W3 was used in this version,
along with the need to click the orange arrow in order to reveal the subsequent
subcategory drop-down menus.
Web site 7 (W7) combined Perceptual and Procedural inconsistencies (Fig-
ure B.7). Buttons and radio buttons replaced the drop-down menus and the
orange arrow had to be clicked to reveal the subsequent subcategory buttons
and radio buttons.
Web site 8 (W8) combined all three inconsistencies (Figure B.8). Thus, the
contact page used buttons and radio buttons, along with interchanged semantics
of the elements in line with W3, together with the need to click the orange arrow
to reveal subsequent subcategory buttons and radio buttons.
2.2.2 Task Sheets
The participants’ task was to assist eight fictive customers in buying three differ-
ent products from the web shop. For this purpose the participants were provided
eight unique task sheets (T1-8; Appendix C) holding pretend customer inform-
ation, including contact, as well as, credit card details. In addition, all task
sheets included (1) three unique products to be purchased in the web shop, (2)
customer request to obtain a specific newsletter, and (3) a contact message from
the customer. On all eight task sheets, the customer message was kept to an
average length of 164 characters (Range: 160-168 characters). All eight tasks
were designed to first introduce the participants to the consistent, baseline fea-
tures of the web shop before they used the experimentally manipulated contact
form.
2.3 Design
As indicated above, the experiment was conducted with a within-subject, 2×
2×2factorial design. The Perceptual, Semantic and Procedural inconsistencies
were the independent variables, where the two levels of the factors represented
presence or absence. One web site in combination with one task (e.g., W6:T2)
was considered a treatment for each participant. All participants were given
eight treatments.
An irregular Latin Square design was adapted in order to counterbalance
the task, as well as, web site order. To minimise carryover effects, four criteria
11
were established for the design of a basic 8×8design matrix:
(1) Every one of the eight participants, in a basic design matrix, should perform
all eight tasks (T1-8), and evaluate all eight web sites (W1-8).
(2) Each web site (W1-8) should be evaluated using all eight tasks (T1-8).
Thus, 8(W ebsites)×8(T asks) = 64 combinations were to be used.
(3) Every one of the eight participants, in a basic design matrix, should use all
the eight web sites (W1-8), combined with a task, in a unique order (i.e.,
Latin Square).
(4) A basic design matrix should be organised in such an order that each of the
eight web sites (W1-8), combined with a task, should be followed by any
other web site only once (i.e., irregular Latin Square).
The four criteria resulted in a design matrix for 8 participants. The pro-
cedure was then repeated to create a different design matrix for another 8 par-
ticipants. In all, it is possible to create 16 unique design matrices based on
these four criteria. The design means that at least 8 — and thereafter multiples
of 8 — participants are necessary in order to secure that an imbalance in the
combination of tasks and web sites will not influence the experimental results.
2.4 Procedure
Data was collected at three separate group sessions with 7 different participants
at each occasion. Each session started with the experimenter reading an intro-
duction aloud for the participants. The participants were asked to read along
in the compendium, or on the computer monitor in front of them. The parti-
cipants were explicitly told to finish each task as fast as they could but with as
few errors as possible.
Before the participants were allowed to start they were instructed to use the
provided pen to circle the treatment number once they had finished a treatment,
and before continuing on to the next. Remember that a treatment consisted of
a web site (W1-8) combined with a task sheet (T1-8). It was stressed that it was
important that the participants finished the treatments in the order given, and
that circling the treatment number should help them to achieve this. The parti-
cipants then entered an individual nine digit identification number on the start
page of the experiment web site, and were redirected to a demographics form
(Figure 2.1a) asking for their year of birth, sex, and computer experience. Once
this form was completed the participants started on their first treatment. The
unique treatment order for each participant was held in a pre-filled relational
database with the individual identification number as a primary key.
Within each treatment, the participants conducted two subsequent tasks:
(1) completing a purchase of three products, and (2) sending a customer con-
tact message to the fictional company behind the web shop (Figure 2.1c). All
information the participants needed was provided on the eight task sheets. A
purchase was completed by placing the three specified products in the shop-
ping basket, creating a new customer account with specified contact details and
desired newsletter, and completing the order with delivery and credit card de-
tails. Sending the message meant finding the web shop’s contact page, entering
12
customer details and specifying the subject, as well as writing the specified
customer message. Once the contact message was sent the participants were
redirected to an evaluation form (Figure 2.1d) where they rated their experi-
ence with the web site (Table 2.1). When the evaluation was submitted, the
participants were redirected to the next web site and they continued on their
next task sheet. When participants had finished all eight treatments, they were
given a consent form allowing for the use of their recorded data in analysis and
they were asked to read and sign it (Appendix D). Completing the experiment
took, on average, 53 minutes (SD = 9 minutes).
2.5 Measurements
There were four dependent variables measured in the experiment divided into
three categories: user efficiency, user error and user satisfaction.
2.5.1 User Efficiency
Efficiency was measured through (1) Time-On-Task for contact form comple-
tion, and (2) Click Rate for selecting a subject on the contact page. Timestamps
where registered as checkpoints throughout the web sites so that activities car-
ried out between these checkpoints could be monitored. Time-On-Task for com-
pleting the contact form was measured between a start point when the user
entered the contact page and an endpoint at contact form submission. Click
Rate was measured by the number of clicks carried out between a start point
at first interaction with the first subcategory selection element and an endpoint
at the last interaction with the last subcategory selection element. The use of
keyboard keys when selecting subject (such as tab, arrow, space bar and enter
keys), as well as mouse clicks, were included in Click Rate. Clicks on the orange
triangle needed to reveal subcategories in the procedurally inconsistent web sites
were intrinsic to the experimental manipulation and were consequently not in-
cluded in Click Rate, because it would have increased the click rate beyond that
needed for the other experimental manipulations. The minimum Click Rate to
select a subject was 6 clicks for all eight web sites (W1-8).
2.5.2 User Error
The number of errors a participant made between subject selection checkpoints
were recorded. User Error was measured as the sum of three types of errors:
(1) Click error — One click error was recorded for each element the parti-
cipant clicked between subject selection checkpoints that was not associ-
ated with choosing the subcategories.
(2) Alert error — One alert error was recorded for each time the participant
received an alert dialogue informing the participant that one of the sub-
categories was missing.
(3) Selection error — One selection error was recorded, on contact form sub-
mittal, for each faulty subcategory the participant had selected.
13
2.5.3 User Satisfaction
User satisfaction was measured as SUS Score by self reported metrics through
an adaptation of Brooke’s (1996) System Usability Scale (SUS). The SUS con-
sists of 10 statements to which users score their degree of agreement on a 5-point
category scale (Disagree-Agree). The 10 original SUS statements were modified
to fit the current study (see Table 2.1). The wordings of the statements are
altered between positive and negative. To calculate the SUS Score, each pos-
itively worded statement is given a score of its scale value minus 1, and each
negatively worded statement is given a score of 5 minus its scale value. The
sum of these scores is then multiplied by 2.5 to give a total percentage score
between 0 and 100, where 100 represents complete satisfaction.
It should be pointed out that users were asked to rate the whole web shop
experience, not just their interaction with the contact form (where the manipu-
lation of the independent variables lies). The rationale behind this decision was
twofold: (1) not to hint to users that the contact form was different in any way
between the separate versions of the web shop, thereby avoiding any priming
effects, and (2) to find out whether inconsistency in a small part of a web site
could affect the whole user experience.
Table 2.1: The 10 SUS statements used for user satisfaction measurements. Adapted
from Brooke (1996).
Statement Wording
1 I think that I would like to use this web site frequently Positive
2 I found the web site unnecessarily complex Negative
3 I thought the web site was easy to use Positive
4 I think I would need the support of a technical person to
be able to use this web site
Negative
5 I found that the various functions in the web site were well
integrated
Positive
6 I thought this web site was too inconsistent Negative
7 I would imagine that most people would learn to use this
web site very quickly
Positive
8 I found the web site very cumbersome to use Negative
9 I felt very confident carrying out the task using this web site Positive
10 I needed to learn a lot of things before I could get going
with this web site
Negative
14
3 Results
3.1 Sample
Data obtained from 16 of the 21 participants were used in the analyses. This
corresponds to the first two complete basic design matrices (see Section 2.3).
Two participants were excluded due to technical errors at data collection, and
their unique treatments were reassigned to two new participants in order to
maintain the design matrices to which they belonged. Data obtained from
another three participants were left out of the analyses because they belonged
to a third, incomplete basic design matrix.
3.2 Handling Covariance
Screening of the data revealed statistically significant Pearson coefficient of cor-
relations between User Error and Time-On-Task, as well as between User Error
and Click Rate (Table 3.1). The Pearson coefficient of correlations between SUS
Score and the other dependent variables, as well as between Time-On-Task and
Click Rate were not statistically different from zero. Because of this pattern of
correlations, four separate multivariate analyses of covariance (MANCOVA) for
repeated measures were conducted in a step-down analysis (cf. Roy-Bargmann
step-down analysis; Tabachnick & Fidell, 2007; see also Finch, 2007). All of
these analyses were conducted using the MANOVA syntax command in SPSS
20 for Mac OS X.
Because SUS Score was largely independent of the other three dependent
variables, there was no need to subject this variable to a step-down analysis.
Nevertheless, in order to minimise the noise in the data, the first MANCOVA
for repeated measures reported below used SUS Score as dependent variable
and User Error, Click Rate, and Time-On-Task as covariates.
The correlations between User Error and Click Rate on the one hand, and
Time-On-Task on the other, indicate that the more errors the participants made,
the more clicks and the more time they needed to complete the contact form.
Thus, the question is whether or not inconsistency in the web page design had
any effect on Click Rate and Time-On-Task over and above the effect of User
Error. To investigate this, a step-down analysis was employed, where User Error,
Click Rate, and Time-On-Task were entered in this order, corresponding to their
theoretical importance. In all these analyses SUS Score was included as covariate
to minimise the noise in the data. Thus the second MANCOVA reported below
used User Error as dependent variable and SUS Score as covariate. The third
MANCOVA used Click Rate as dependent variable and User Error and SUS
Score as covariates. The forth MANCOVA used Time-On-Task as dependent
variable and Click Rate, User Error and SUS Score as covariates.
Because there were correlations between the dependent variables, and that
four separate MANCOVA were conducted, it was motivated to apply a Bonfer-
roni correction to minimise the risks of committing Type I errors (Tabachnick
& Fidell, 2007; see also Perneger, 1998). This resulted in the need for analysis
of statistical significance at the 0.01 level (Equation 3.1).
α= 1 (1 0.01)40.039 (3.1)
15
Table 3.1: Pearson’s coefficient of correlations between dependent variables: SUS
Score, User Error, Click Rate, and Time-On-Task.
SUS Score User Error Click Rate
User Error -.029
Click Rate .079 .187
Time-On-Task .016 .227.026
p < 0.05 (two-tailed).
Table 3.2: F-statistics of 2 (Perceptual inconsistency) ×2 (Semantic inconsistency)
×2 (Procedural inconsistency) repeated measures MANCOVA for SUS Score, User
Error, Click Rate, and Time-On-Task.
Sus ScoreaUser ErrorbClick RatecTime-On-Taskd
Factor F1,12 pF1,14 pF1,1 3 pF1,12 p
PERceptual 4.51 0.055 0.11 0.744 0.88 0.364 10.280.008
SEMantic 0.57 0.466 0.22 0.648 7.70 0.016 0.16 0.694
PROcedural 3.61 0.082 31.70<0.001 2.20 0.162 1.27 0.282
PER*SEM 0.01 0.931 2.50 0.136 1.53 0.238 0.50 0.493
PER*PRO 1.40 0.260 0.21 0.651 6.59 0.023 0.04 0.843
SEM*PRO 5.28 0.040 0.03 0.875 0.05 0.829 0.96 0.347
PER*SEM*PRO 0.84 0.377 4.90 0.044 1.35 0.265 0.68 0.424
p < 0.01.
aSUS Score with User Error, Click Rate and Time-On-Task as covariates.
bUser Error with SUS Score as covariate.
cClick Rate with User Error and SUS Score as covariates.
dTime-On-Task with Click Rate, User Error and SUS Score as covariates.
3.3 User Satisfaction
Figure 3.1 presents a factor plot for SUS Score, using the observed mean values,
divided on the three independent variables: Perceptual, Semantic and Proced-
ural inconsistency.
The plot indicates that SUS Score decreases when any of the three incon-
sistencies are introduced alone. However, there is a tendency that Semantic
inconsistency inhibits Procedural inconsistency, which creates an interaction ef-
fect.
Table 3.2 presents F-statistics for the four individual MANCOVA analyses.
The results for SUS Score confirm most of the tendencies indicated in the factor
plot in Figure 3.1, particularly the interaction between Semantic and Procedural
inconsistency. However, none of the effects are statistically significant at the 0.01
level.
Absent Present
75
80
85
90
Absent Present Absent Present
Semantic inconsistency
Mean values of SUS Score
Procedural inconsistency
Absent
Present
Perceptual inconsistency
Figure 3.1: Observed mean values of SUS Score divided on the three factors Percep-
tual, Semantic, and Procedural inconsistency. Each factor has two levels: absence or
presence. Error bars represents standard errors of the mean values (±1 SE).
17
3.4 User Error
Figure 3.2 presents a factor plot for User Error, using the observed mean
frequencies, divided on the three independent variables: Perceptual, Semantic
and Procedural inconsistency.
The plot indicates that User Error increases when Procedural inconsistency
is introduced. The MANCOVA confirms this main effect, which is statistically
significant at the 0.01 level (Table 3.2).
Perceptual and Semantic inconsistency shows little to no effect on User Er-
ror when introduced alone. However, there is a tendency towards a complex
three-way interaction effect between the three inconsistencies. Both Perceptual
and Semantic inconsistency tends to inhibit the negative effect of Procedural
inconsistency on User Error. On the other hand, Perceptual and Semantic incon-
sistency also tends to cancel each other out. Thus, when all three inconsistencies
are introduced together, Procedural inconsistency is as influential as when in-
troduced alone. However, the three-way-interaction effect is not statistically
significant at the 0.01 level (Table 3.2).
Figure 3.2: Observed mean frequencies of User Error divided on the three factors Per-
ceptual, Semantic, and Procedural inconsistency. Each factor has two levels: absence
or presence. Error bars represents standard errors of the mean frequencies (±1 SE).
18
3.5 User Efficiency
3.5.1 Click Rate
Figure 3.3 presents a factor plot for Click Rate, using the observed mean fre-
quencies, divided on the three independent variables: Perceptual, Semantic and
Procedural inconsistency.
The plot indicates that Click Rate increases when Semantic inconsistency
is introduced. This tendency, although not statistically significant at the 0.01
level, is apparent in Table 3.2.
Neither Perceptual nor Procedural inconsistency has any effect on Click Rate
alone but both separately tends to inhibit the negative effect of Semantic in-
consistency on Click Rate. When combined they boost the effect of Semantic
inconsistency, resulting in a peak value of Click Rate when all inconsistencies are
present. However, both these effects disappear once User Error and SUS Score
are controlled for as shown in Table 3.2. A tendency towards a two-way in-
teraction effect between Perceptual and Procedural inconsistency also becomes
evident once these factors are controlled for, which is not as clear in the observed
means in the plot.
Absent Present
7
8
9
10
Absent Present Absent Present
Semantic inconsistency
Mean frequencies of Click Rate
Procedural inconsistency
Absent
Present
Perceptual inconsistency
Figure 3.3: Observed mean frequencies of Click Rate divided on the three factors Per-
ceptual, Semantic, and Procedural inconsistency. Each factor has two levels: absence
or presence. Error bars represents standard errors of the mean frequencies (±1 SE).
19
3.5.2 Time-On-Task
Figure 3.4 presents a factor plot for Time-On-Task, using the observed mean
durations (s), divided on the three independent variables: Perceptual, Semantic
and Procedural inconsistency.
The plot indicates that each of the three inconsistencies alone has an effect,
resulting in an increase in Time-On-Task.
Semantic inconsistency tends to inhibit the effect of Procedural inconsist-
ency, whereas Perceptual inconsistency only has a small effect on the other two
inconsistencies. However, when all three inconsistencies are combined, the effect
is cumulative and results in the longest completion time. Table 3.2 shows that
after controlling for the effect of Click Rate, User Error and SUS Score only
the main effect of Perceptual inconsistency reaches statistical significance at the
0.01 level.
Absent Present
90
100
110
120
130
Absent Present Absent Present
Semantic inconsistency
Mean durations of Time−On−Task (s)
Procedural inconsistency
Absent
Present
Perceptual inconsistency
Figure 3.4: Observed mean durations of Time-On-Task divided on the three factors
Perceptual, Semantic, and Procedural inconsistency. Each factor has two levels: ab-
sence or presence. Error bars represents standard errors of the mean durations (±1
SE).
20
4 Discussion
The present experiment resulted in statistically significant main effects (p <
0.01) of both Perceptual and Procedural inconsistencies on user performance
(i.e., User Error, Click Rate, or Time-On-Task). Procedural inconsistency res-
ulted in more errors being made, whereas Perceptual inconsistency prolonged
task completion time independently of the number of errors made (Table 3.2).
Semantic inconsistency, on the other hand, tended to increase the number of
clicks necessary to select a subject on the contact page (p= 0.016).
The inconsistencies in the contact form had only weak effects on the users’
satisfaction (i.e., SUS Score) of the web shop as a whole. The effects were not
statistically significant (Table 3.2), and overall the users gave the web shop a
high SUS Score (see Figure 3.1; according to Tullis & Albert, 2008, 80 is a
fairly good score).
To our knowledge, the present study is the first in examining full factorial
interaction effects of inconsistencies from a user’s perspective. A few interest-
ing, and unexpected, interaction effects were indicated, even though none were
statistically significant at the 0.01 level. Based on previous research, it was spec-
ulated that any interaction effects should be cumulative. However, the present
results indicate that Semantic, as well as, Perceptual inconsistency inhibited
the effects caused by Procedural consistency. Semantic consistency tended to
protect against the negative influence Procedural consistency had on user sat-
isfaction, whilst both Semantic and Perceptual consistency tended to suppress
the number of errors made in Procedural inconsistent versions of the web shop.
That Perceptual inconsistency had negative impact on user performance
coincide with the findings of Adamson (1996), Ozok and Salvendy (2000), and
AlTaboli and Abou-Zeid (2007) on physical inconsistency. However, they found
evidence that it increased errors made by users, whereas the present study found
that it prolonged task completion time.
The results that Procedural inconsistency increased errors made by users
agrees with the findings of Adamson (1996) with regard to communicational
inconsistency.
Kellogg’s (1987) manipulation of conceptual consistency was close to the
definition of Semantic consistency of the present thesis. Although the present
study lacked statistically significant results for the effects of Semantic consist-
ency, it did show tendencies to correspond with the findings of Kellogg (1987)
that it may affect user performance.
4.1 Implications
The present experiment shows that graphical designers should avoid designing
inconsistent procedures within web sites from a user’s point of view. Inconsist-
ency in procedure may lead to users making more errors. To achieve proced-
urally consistent web design, developers must analyse the procedures from the
user’s perspective.
The present experiment also indicates that Semantic inconsistency may pro-
tect against Procedural inconsistency’s negative impact on user satisfaction.
This could be that once one changes the appearance or placement of an object,
it indicates to the user that a different procedure is necessary. This potential in-
teraction effect indicates that users may regard an object, which has more than
21
one inconsistency in relation to another object, as a completely new object, and
therefore judge it differently.
An interesting result from the present experiment is that Perceptual incon-
sistency affects Time-On-Task independently of the number of errors, and the
number of clicks a user made. This suggests that the prolonged completion
time was due to cognitive load of the inconsistency. This implies that change in
visual appearance makes users think more about their actions.
Taken together, the results show that inconsistencies might be used to sig-
nal change. However, designers should be sure to signal this with perceivable
changes in order to minimise the risks of errors being made.
4.2 Limitations
Apart from the two statistically significant main effects of Perceptual and Pro-
cedural inconsistencies on user performance, some additional but weak effects
were found. That only two effects were statistically significant at the 0.01 level
may be due to at least three factors: (1) the experimental manipulation was
faulty, (2) the experimental manipulation was to weak, or (3) the sample size
was too small.
4.2.1 Faulty Manipulation
The definitions of the three categories of consistency proposed in Section 1.2.3,
were strictly adhered to in designing the eight versions of the web shop (W1-
8). Therefore there should be no question that the manipulation of Perceptual,
Semantic, and Procedural inconsistency was true to the proposed definitions.
4.2.2 Weak Experimental Manipulation
As explained in Section 2.5.3, users evaluated their experience with the whole
web shop. This is possibly the reason why there were no strong results on
the effects of user satisfaction. More powerful inconsistencies might have to be
introduced in order to affect user satisfaction when only a part of a web site
is manipulated. Naturally, the evaluation could have been on just the contact
form to achieve stronger results. However, as elaborated earlier, this could have
had a priming effect on the participants in the experiment.
No significant results were found for Semantic consistency. It can be argued
that the manipulation of Semantic consistency was too simple to affect on the
user experience. The question arises whether the interchange of visual appear-
ance (see Figure B.3) really made a semantic difference to the user. However,
the effects on Click Rate are close to being statistically significant, with regard
to Semantic inconsistency, and the notion that it affected user performance can
therefore not be rejected.
4.2.3 Too Small Sample
The most probable cause for the few statistically significant effects is that too
few participants were used. A couple of the values presented in Table 3.2 are
22
approaching statistical significance (i.e., Semantic inconsistency’s effect on Click
Rate, and the two-way-interaction effect between Perceptual and Procedural
consistency on Click Rate). This indicates that using a larger sample may yield
stronger results.
4.3 Further Research
Computer science, and thereby user interface design, will likely keep on expand-
ing into unknown territories. Studies on the impact of consistency can therefore
help us predict, and counteract, future usability issues.
Previous research and the present experiment makes it evident that incon-
sistency does affect user performance. It also shows that inconsistency can have
an effect on user satisfaction, although, the present study did not find statistic-
ally significant evidence for this.
An in-depth analysis of the manipulations carried out in all studies on con-
sistency within HCI could help to home in on the essence of consistency. This
could help to understand how these manipulations of consistency lead to such
different results. One probable reason might be that there is another level to
consistency than just categories. For example, it would be interesting to com-
bine an experiment such as ours along with Norman’s (2001) seven stages of
action (Figure 4.1), which suggests that a user goes through seven stages of
action when interacting with, for instance, a web site. This would be a use-
ful approach in order to see in what stage of interaction any of the proposed
consistencies would affect user performance and satisfaction.
It would also be useful to carry out separate experiments on each of the
three proposed consistencies and thereby test several different manipulations of
each consistency.
Figure 4.1: Norman’s seven stages of action. Redrawn from Norman (2001).
23
4.4 Conclusions
1. Inconsistent web design results in more user errors being made and in
longer task completion times.
2. Viewing the system from a user’s perspective aids developers and designers
to build consistent web applications.
3. The results of the present thesis indicate that there are interaction ef-
fects between different types of inconsistency, which needs to be further
explored.
24
Acknowledgements
Special thanks go to Dr. Östen Axelsson, Department of Psychology, Stockholm
University, for advices on research methods, statistics and scientific writing, as
well as valuable comments on the text.
Special thanks also go to Mette Clausen-Bruun for proof reading and valu-
able comments on the text.
Special thanks is also directed towards Dr. F. Layne Wallace, Department of
Computer and Information Sciences, University of Northern Florida, for finding
and forwarding a copy of Adamson (1996).
Special thanks also go to the 21 persons who volunteered to participate in
the present experiment.
25
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27
Appendices
A Baseline Choice Selections
Figure A.1: Newsletter choice at customer registration.
Figure A.2: Card expiry date choice at checkout.
B Variations of Inconsistency in Subject System
Figure B.1: Choice selection fully consistent with the baseline newsletter and expiry
date selections (W1).
Figure B.2: Perceptually inconsistent choice selection (W2).
Figure B.3: Semantically inconsistent choice selection (W3).
Figure B.4: Procedurally inconsistent choice selection (W4).
Figure B.5: Perceptually and Semantically inconsistent choice selection (W5).
Figure B.6: Semantically and Procedurally inconsistent choice selection (W6).
Figure B.7: Perceptually and Procedurally inconsistent choice selection (W7).
Figure B.8: Perceptually, Semantically, and Procedurally inconsistent choice selection
(W8).
C Task Compendium
Teknik och Samh¨alle
Datavetenskap
Experiment i anv¨andbarhet
CBG: 0
ID: 123456782
Anton Axelsson
m09p0891@student.mah.se
Introduktion
Detta ¨
ar ett experiment om anv¨
andbarhet p˚a webben. Syftet ¨
ar att testa
en webbapplikations funktionalitet i ˚atta olika utformningar. Din uppgift
¨
ar att hj¨
alpa ˚atta personer att inhandla produkter fr˚an f¨
oretaget Web-
shoppen, samt hj¨
alpa dem kontakta Webshoppen via webbsidans kontak-
tformul¨
ar.
Detta kompendium best˚ar av ett f¨
ors¨
attsblad, denna introduktion, samt
˚atta uppgiftssidor med den information, samt de instruktioner du beh¨
over
f¨
or att genomf¨
ora experimentet.
Varje uppgift (1-8) best˚ar av f¨
oljande delmoment och skall utf¨
oras i an-
given ordning:
1. Hitta och l¨
agga de 3 angivna produkterna i varukorgen (observera
att s¨
okfunktionen f¨
or produkter ¨
ar avst¨
angd).
2. Registrera konto via kassan med
angivna kontaktuppgifter.
angivet ¨
onskat nyhetsbrev.
angivet ¨
onskat l¨
osenord.
3. Ange kortuppgifterna och slutf¨
or k¨
opet.
4. Skicka meddelande till Webshoppen med angiven f¨
orfr˚agan via webb-
platsens kontaktformul¨
ar.
N¨
ar meddelandet har skickats kommer du att omdirigeras till en sida d¨
ar
du ombeds utv¨
ardera din upplevelse av den senast anv¨
anda webbapplika-
tionen. N¨
ar du sparat dina svar kommer du att omdirigeras till Webshop-
pen igen och du p˚ab¨
orjar d˚a uppgiften p˚a n¨
asta blad.
N¨
ar du genomf¨
ort samtliga ˚atta uppgifter ber vi dig kalla p˚a experimen-
tledaren som kommer att ge dig ett medgivandeformul¨
ar f¨
or din under-
skrift.
Speciellt viktigt att komma ih˚ag under experimentet ¨
ar:
Den tid du tar p˚a dig samt de fel du g¨
or kommer att m¨
atas. D¨
arf¨
or
¨
ar det viktigt att du h˚aller dig till uppgiften och f¨
ors¨
oker utf¨
ora de
˚atta uppgifterna s˚a fort du kan men med s˚a f˚a fel som m¨
ojligt.
Inga m¨
atningar g¨
ors under utv¨
arderingarna mellan uppgifterna, du
har d˚a m¨
ojlighet att ta en paus om du s˚a ¨
onskar.
Vissa uppgifter kan upplevas vara sv˚ara, men de g˚ar att l¨
osa s˚a tappa
inte modet.
Detta ¨
ar INTE ett test av dig och dina kunskaper eller f¨
aridgheter,
utan ett test av hur v¨
al de olika utformningarna av webbapplikation
fungerar.
Om tekniska problem uppst˚ar eller om du undrar ¨
over n˚agot s˚a kontakta
experimentledaren. N¨
ar du k¨
anner dig redo kan du p˚ab¨
orja experimentet
genom att ange ditt niosiffriga ID. Ditt ID finner du p˚a f¨
ors¨
attsbladet. Ex-
perimentet b¨
orjar med ett mindre fr˚ageformul¨
ar d¨
ar du anger f¨
odelse˚ar,
k¨
on och datorvana.
Uppgift 1
Kontaktuppgifter
Alfred G¨
oransson
Tallgatan 11 C
523 35 ULRICEHAMN
alfred.goransson@skatteverket.se
073 - 159 595 55
¨
Onskat l¨
osenord: letmein
Kortuppgifter
Korttyp: MasterCard
Kortnummer: 5454 9963 1215 9875
Giltigt tom: 09 / 2012
S¨
akerhetskod: 951
Instruktioner
Genomf¨
or k¨
op
Alfred ber dig k¨
opa f¨
oljande produkter:
Boken ’Version Control with Git: Powerful Techniques for Certralized and
Distributed Project Management’ (Data & IT)
Filmen ’The Big Lebowski - Special Edition’ (Komedi)
CD-skivan ’Free The Bees’ (Alternativt & Indie)
Nyhetsbrev
Alfred vill ha nyheter g¨
allande alla produkter.
Skicka kontaktmeddelande
Efter att du genomf¨
ort k¨
opet vill Alfred att du kontaktar Webshoppen f¨
or att
ber¨
omma dem f¨
or snabb leverans, men inte f¨
or n˚agon s¨
arskild produkt. G˚a till
kontaktsidan och fyll i formul¨
aret. Ange f¨
oljande meddelande:
Jag fattar inte hur ni lyckas! Jag best¨
allde mina produkter ig˚ar och idag ¨
ar de
redan h¨
ar. M˚aste s¨
aga att ni g¨
or ett fantastiskt jobb. Keep up the good work!
Uppgift 2
Kontaktuppgifter
Lisa St˚
ahlski¨
old
Expressv¨
agen 55
168 53 BROMMA
lisa stahlis@hotmail.com
070 - 961 963 91
¨
Onskat l¨
osenord: tellno1
Kortuppgifter
Korttyp: VISA
Kortnummer: 4646 8366 9991 0105
Giltigt tom: 01 / 2013
S¨
akerhetskod: 883
Instruktioner
Genomf¨
or k¨
op
Lisa ber dig k¨
opa f¨
oljande produkter:
Filmen ’Eyes Wide Shut’ (Thriller & Skr¨
ack)
CD-skivan ’We Sweat Blood’ (Rock)
CD-skivan ’Cosmo’s Factory’ (Rock)
Nyhetsbrev
Lisa vill ha samtliga nyhetsbrev g¨
allande musik.
Skicka kontaktmeddelande
Efter att du genomf¨
ort k¨
opet vill Lisa att du kontaktar Webshoppen f¨
or att
kontrollera status p˚a en musikorder hon lagt tidigare i ˚ar. G˚a till kontaktsidan
och fyll i formul¨
aret. Ange f¨
oljande meddelande:
F¨
or drygt en m˚anad sedan lade jag en order (nummer 9152138) hos er p˚a fler-
talet CD-skivor, vissa skivor var d˚a sluts˚alda. N¨
ar kan jag f¨
orv¨
antas f˚a denna
order?
Uppgift 3
Kontaktuppgifter
Eva Strandsj¨
o
Storgatan 114
214 22 MALM¨
O
eva@live4film.se
070 - 193 124 25
¨
Onskat l¨
osenord: password12
Kortuppgifter
Korttyp: MasterCard
Kortnummer: 5655 9984 1211 3754
Giltigt tom: 12 / 2016
S¨
akerhetskod: 112
Instruktioner
Genomf¨
or k¨
op
Eva ber dig k¨
opa f¨
oljande produkter:
Boken ’Truth’ (Filosofi)
Filmen ’Inception’ (Action & ¨
Aventyr)
Filmen ’Scarface (Blu-ray)’ (Action & ¨
Aventyr)
Nyhetsbrev
Eva vill ha erbjudanden g¨
allande filmer.
Skicka kontaktmeddelande
Efter att du genomf¨
ort k¨
opet vill Eva att du kontaktar Webshoppen f¨
or att
beg¨
ara en retur av tidigare best¨
allda filmer som hon ˚angrar att hon k¨
opt. G˚a
till kontaktsidan och fyll i formul¨
aret. Ange f¨
oljande meddelande:
Hej, idag fick jag en leverans av filmer fr˚an ett k¨
op som jag inte trodde hade
g˚att igenom, d¨
arf¨
or har jag redan inhandlat dem p˚a annat s¨
att. Hur g¨
or jag nu?
Uppgift 4
Kontaktuppgifter
Abir Sahlir
Bj¨
orkgatan 13 D
571 95 N¨
ASSJ¨
O
abir.sahlir@help-it.se
070 - 987 537 12
¨
Onskat l¨
osenord: 789secret
Kortuppgifter
Korttyp: VISA
Kortnummer: 4041 4456 1441 3451
Giltigt tom: 08 / 2013
S¨
akerhetskod: 415
Instruktioner
Genomf¨
or k¨
op
Abir ber dig k¨
opa f¨
oljande produkter:
Boken ’Design Patterns’ (Data & IT)
Boken ’Information Retrieval’ (Data & IT)
Filmen ’Taxi’ (Action & ¨
Aventyr)
Nyhetsbrev
Abir vill ha erbjudanden g¨
allande b¨
ocker.
Skicka kontaktmeddelande
Efter att du genomf¨
ort k¨
opet vill Abir att du kontaktar Webshoppen f¨
or att
klaga p˚a produktavdelningen f¨
or deras begr¨
ansade utbud p˚a b¨
ocker. G˚a till
kontaktsidan och fyll i formul¨
aret. Ange f¨
oljande meddelande:
Jag har flertalet g˚anger kontaktat er i detta ¨
arende och jag f˚ar aldrig n˚agot
ordentligt svar p˚a varf¨
or ni aldrig kan ta in n˚agra vettiga b¨
ocker om HTML5!
Uppgift 5
Kontaktuppgifter
Suzanna Kowalski
Pressv¨
agen 1
977 53 LULE˚
A
daemon slayer@live.com
073 - 156 353 31
¨
Onskat l¨
osenord: daemons
Kortuppgifter
Korttyp: MasterCard
Kortnummer: 5551 5154 3589 9785
Giltigt tom: 05 / 2017
S¨
akerhetskod: 134
Instruktioner
Genomf¨
or k¨
op
Suzanna ber dig k¨
opa f¨
oljande produkter:
Boken ’Gruppsykologi : om grupper, organisationer och ledarskap’ (Psykolo-
gi & Kognition)
Filmen ’The Shining’ (Thriller & Skr¨
ack)
CD-skivan ’Fear Of Fours’ (Electronica)
Nyhetsbrev
Suzanna vill ha nyheter g¨
allande alla produkter.
Skicka kontaktmeddelande
Efter att du genomf¨
ort k¨
opet vill Suzanna att du kontaktar Webshoppen f¨
or att
¨
andra den nyss lagda ordern och byta ut en musikartikel. G˚a till kontaktsidan
och fyll i formul¨
aret. Ange f¨
oljande meddelande:
Alldeles nyss lade jag en best¨
allning med ordernummer 9153616. Jag undrar om
jag kan byta ut skivan “Fear of fours“ med Lamb till deras sj¨
alvbetitlade ist¨
allet?
Uppgift 6
Kontaktuppgifter
Anders Bengtson
Tunav¨
agen 33
424 17 ANGERED
bengtson991@gmail.com
070 - 965 461 24
¨
Onskat l¨
osenord: qwerty
Kortuppgifter
Korttyp: VISA
Kortnummer: 4587 5468 2164 3112
Giltigt tom: 01 / 2014
S¨
akerhetskod: 995
Instruktioner
Genomf¨
or k¨
op
Anders ber dig k¨
opa f¨
oljande produkter:
Filmen ’F˚aglarna (1963)’ (Thriller & Skr¨
ack)
CD-skivan ’Pendulum’ (Rock)
CD-skivan ’Blue Train’ (Jazz & Eklektiskt)
Nyhetsbrev
Anders vill ha nyheter g¨
allande filmer.
Skicka kontaktmeddelande
Efter att du genomf¨
ort k¨
opet vill Anders att du kontaktar Webshoppen f¨
or
att ta reda p˚a om det g˚ar att ¨
andra betalmetod f¨
or den nyss lagda ordern in-
neh˚allande flera typer av produkter. G˚a till kontaktsidan och fyll i formul¨
aret.
Ange f¨
oljande meddelande:
Precis n¨
ar ordern lades s˚ag jag att det inte fanns til lr¨
ackligt med pengar p˚a mitt
konto. Finns det m¨
ojlighet att ¨
andra s˚a att ordern g˚ar p˚a faktura ist¨
allet?
Uppgift 7
Kontaktuppgifter
Lovisa Granstedt
Risgrynsstigen 21
654 55 KARLSTAD
lovisa@granstedt.se
070 - 751 752 23
¨
Onskat l¨
osenord: passw0rd
Kortuppgifter
Korttyp: MasterCard
Kortnummer: 5346 8549 6172 4587
Giltigt tom: 03 / 2015
S¨
akerhetskod: 315
Instruktioner
Genomf¨
or k¨
op
Lovisa ber dig k¨
opa f¨
oljande produkter:
Filmen ’Nyckeln till frihet (Blu-ray)’ (Drama)
Filmen ’Limitless’ (Action & ¨
Aventyr)
CD-skivan ’I Am Not A Doctor’ (Electronica)
Nyhetsbrev
Lovisa vill ha samtliga nyhetsbrev g¨
allande alla produkter.
Skicka kontaktmeddelande
Efter att du genomf¨
ort k¨
opet vill Lovisa att du kontaktar Webshoppen f¨
or att
g¨
ora en allm¨
an f¨
orfr˚agan om betalning, men inte f¨
or n˚agon s¨
arskild produkt. G˚a
till kontaktsidan och fyll i formul¨
aret. Ange f¨
oljande meddelande:
S˚ag att ni bara erbjuder faktura och kortbetalningar som alternativ. Skulle ni
inte kunna erbjuda Paypal som ett alternativ? Det skulle underl¨
atta en hel del.
Uppgift 8
Kontaktuppgifter
Claes-G¨
oran Ahl
Bergshyttan
290 62 VILSHULT
classe@skogsmaskinen-ab.se
073 - 553 785 12
¨
Onskat l¨
osenord: 1q2w3e
Kortuppgifter
Korttyp: VISA
Kortnummer: 4646 2135 4875 1294
Giltigt tom: 11 / 2016
S¨
akerhetskod: 437
Instruktioner
Genomf¨
or k¨
op
Claes-G¨
oran ber dig k¨
opa f¨
oljande produkter:
Filmen ’Singin’ in the Rain’ (Komedi)
CD-skivan ’A Musical Ramance’ (Jazz & Eklektiskt)
CD-skivan ’Lockar Och Sk¨
agg’ (Jazz & Eklektiskt)
Nyhetsbrev
Claes-G¨
oran vill ha erbjudanden g¨
allande musik.
Skicka kontaktmeddelande
Efter att du genomf¨
ort k¨
opet vill Claes-G¨
oran att du kontaktar Webshoppen
f¨
or att klaga p˚a kundtj¨
anst, men inte om n˚agon s¨
arskild produkt. G˚a till kon-
taktsidan och fyll i formul¨
aret. Ange f¨
oljande meddelande:
Varf¨
or svarar ni aldrig? Jag har kontaktat er flera g˚anger via telefon men man
kommer aldrig fram ist¨
allet hamnar man bara i n˚agot slags limbo. Sk¨
arpning!!!
D Consent Form
Medgivandeformulär
Experimentledare: Anton Axelsson
m09p0891@student.mah.se
Experiment: Inkonsistens påverkan på användbarhet
Beskrivning
Detta experiment går ut på att utröna hur användare påverkas av inkonsistens i webdesign.
Experimentet består av åtta versioner av en webbapplikation. Till varje applikationsversion skall
tre uppgifter utföras.
Köp av varor
Du genomför ett köp av ett antal specificerade varor och registrerar kunduppgifter.
Utformande av meddelande
Du fyller i ett kontaktformulär och skickar ett meddelande till det fingerade företaget bakom
webbapplikation.
Utvärdering
Du utvärderar uppgiften samt applikationsversionens utförande.
Medgivande
Jag medger härmed att jag har . . .
. . . blivit informerad om experimentets syfte och tillåter att den insamlade informationen be-
varas till dess att den publiceras.
. . . förstått att den insamlade informationen rapporteras och bevaras i anonym form och att
experimentledaren enligt svensk lag, under ovanliga omständigheter, kan tvingas lämna ut
informationen till andra forskare för granskning av eventuella brister.
. . . förstått att min uttryckliga värdering av applikationsversionerna, uppgifterna samt ålder,
kön och datorvana sparas.
. . . förstått innehållet i detta dokument
Ort och datum Namnförtydligande Underskrift
Kompletterande klausul
Jag ger mitt medgivande till att den insamlade informationen publiceras online vilket ger andra
forskare möjligheten att använda sig av informationen i det syfte de finner lämpligt.
Ort och datum Namnförtydligande Underskrift
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