The ABCs of UX: The Diverse Disciplines

“To understand what the user is looking for in the things he is looking at.”

The current post is the first one in the series of 3 posts, where I would like to clarify the definitions and concepts that are core to our context covering User Experience (UX), Information Architecture(IA) and Interaction Design (IxD).

User Experience (UX)

Fig: 1

User experience (UX) is a convergence of several disciplines. There is no final fool-proof list of disciplines which come together to form it. But yes, there are many popular explanations by social scientists, industrial designers and information architects which describe it as a combination of a verity of disciplines.

The most popular and accepted compilation of disciplines is shown in Fig 1 where it is represented as a combination of :

  1. Information Architecture (IA)
  2. Visual Design
  3. Industrial Design
  4. Human Factors
  5. Interaction Design (IxD)
  6. Human — Computer Interaction (HCI)
  7. Architecture

There are variations available to this where commercial aspects are added to it . Fig 2 represents such a case.

Fig: 2

In Fig:2, you can see the UX definition has been seen as all those disciplines which can work together to provide a solution that can deliver “customer with a harmonious and consistent experience”.

User experience (UX or UE) involves a person’s emotions about using a particular product, system or service. User experience highlights the experiential, affective, meaningful and valuable aspects of human-computer interaction and product ownership. Additionally, it includes a person’s perceptions of the practical aspects such as utility, ease of use and efficiency of the system. User experience is subjective in nature because it is about individual perception and thought with respect to the system. User experience is dynamic as it is constantly modified over time due to changing circumstances and new innovations.”

If you notice all the aspects such as “branding” and “customer service” are related with emotional aspect of human behavior. So user experience is also about emotions and psychological dimensions of customer’s perceptions about the product. Wikipedia also defines “User Experience” as :

a person’s perceptions and responses that result from the use or anticipated use of a product, system or service”. According to the ISO definition user experience includes all the users’ emotions, beliefs, preferences, perceptions, physical and psychological responses, behaviors and accomplishments that occur before, during and after use. The ISO also list three factors that influence user experience: system, user and the context of use.

Similarly ISO 9241–210 defines user experience as:

So basically, “User Experience” deals with the “How” factor of the product or system rather than it’s “What” factor. Most of the customers buy the product not because simply “what it does”, rather the “how” factor takes priority when it comes to choose from a several similar products.

We will dive deep throughout this series, but before that let’s see clear similar jargon.

Information Architecture (IA)

While exploring UX in previous section, we saw that Information Architecture (IA) is one of the contributing disciplines which form the total User Experience. During 1960’s ,Richard Saul Wurman, an architect by profession having skills of a graphic designer, author and an editor of numerous fine graphics related books, coined the term “Information Architecture”. He mostly developed concepts “ in the ways in which information about urban environments could be gathered, organized, and presented in meaningful ways to architects, to urban planners, to utility and transport engineers, and especially to people living in or visiting cities”. Later these impacted a set of disciplines such as library- and information-science (LIS) , graphic design and in recent years the world wide web (www). During 1990’s , with the evolution of the Web, there rose the need to rethink the presentation of library-catalog information as this information has been moved into online public-access catalogs, and in part to the proliferation of information on the Web itself. So during 90’s IA has taken on something of a connotation of applying especially to the organization of information on the World-Wide Web.

Fig: 3

Basically Information Architecture (IA), all about organizing information in a meaningful way so that the user can easily find it when needed through proper organization, navigation, labeling, andsearchingsystems.IA also takes care of the process that ensures that there is no information breakdown or explosion with the scaling of information overtime.

Fig:3 represents the 3 basic ingredients of IA, namely:

Users: This represents those who will use the product or system, their “information seeking behavior” and their needs. Any of the following roles/skills/features can be applied to them:

Content: This is what is presented to the users through the product or system. This includes the data or information that is offered, along with its aspects such as volume, metadata, structure and organization. Sample skills/roles/features/concepts revolving around content are:

Context: This is what gives meaning to the content that is being served to the user. This can have the attributes like business model, business value, resource, resource constraints, culture etc. The following features/roles/skills are associated with context:

Interaction Design (IxD)

Wikipedia defines Interaction Design as:

In design, human–computer interaction, and software development, interaction design, often abbreviated IxD, is “about shaping digital things for people’s use”

Interaction design involves attributes of several related disciplines such as :

  1. Design research
  2. Human–computer interaction
  3. Cognitive psychology
  4. Human factors and ergonomics
  5. Industrial design
  6. Architecture
  7. User interface design

Interaction design focuses more on human behavior through scientific tools and statistics, even when it is in fact is opposed to the disciplines which focus on “how things are” . Even when it uses tools that span across design and engineering domains, by it’s ability to perform “synthesis and imagining things as they might be” makes it a part of “designing” field.

In his book Designing Interactions. Gillian Crampton Smith, defined 4 dimensions of Interaction Design, to which Kevin Silver later added the 5 and the most important dimension (i.e. behaviour).

Fig: 4

Fig. 4 represents the 5 dimensions of IxD namely:

  1. Words: This dimension defines the interactions. Words are the interaction that users use to interact with.
  2. Visual Representations: The visual representations are the things that the user interacts with on the interface. These may include but not limited to “typography, diagrams, icons, and other graphics”
  3. Physical objects or space: The space with which the user interacts is the third dimension of interaction design. It defines the space or objects “with which or within which users interact with”
  4. Time: The time with which the user interacts with the interface. Some examples of this are “content that changes over time such as sound, video, or animation”
  5. Behavior: The behavior defines the users’ actions reaction to the interface and how they respond to it.

Many confuse between Interaction Design with User Interface design, as in most cases interaction design is associated with the designing activities of interfaces. However Interaction Design focuses more “on the aspects of the interface that define and present its behavior over time, with a focus on developing the system to respond to the user’s experience and not the other way around”.

User Interface Design (UI)

Wikipedia defines it as :

User interface designor user interface engineering is the design of computers, appliances, machines, mobile communication devices, software applications, and websites with the focus on the user’s experience and interaction. The goal of user interface design is to make the user’s interaction as simple and efficient as possible, in terms of accomplishing user goals — what is often called user-centered design. Good user interface design facilitates finishing the task at hand without drawing unnecessary attention to itself. Graphic design may be utilized to support its usability. The design process must balance technical functionality and visual elements (e.g., mental model) to create a system that is not only operational but also usable and adaptable to changing user needs.

User Interface design is somewhat “the form-giving counterpart to interaction design”. User Interface design differs from interaction design primarily in “ its focus on the behavior of artifacts rather than the behavior of humans”.In UI, the center of all the focus is artifacts that makes the interface, where as in case of IxD it is the human behavior that takes the center stage.

In case of a Software production process the UI is more associated with the Graphical User interface designer. In industrial design case, UI is more tilted towards the industrial designer.


The Fig:5, shows various disciplines that contribute to User Interface Design.

Usability and Mental Models: Foundations of UX

What is Usability?

In 1998, the International Standards Organization (ISO),the organization well known for development of standards for industrial processes and product quality, defined“usability” as :

the effectiveness, efficiency and satisfaction with which specified users achieve specified goals in a particular environment. (ISO 9241)

ISO model prescribed the following 3 criteria as components of usability:

  1. Effectiveness: accuracy and completeness with which specified users can achieve specified goals in a particular environment
  2. Efficiency: the resources expended in relation to the accuracy and completeness of the goals achieved
  3. Satisfaction: the comfort and acceptability of the work system to its users and other people affected by its use.

One year later , in 1999, Cosantine and Lockwood defined ‘usability’ as:

being composed of the learnability, retainability, efficiency of use, and user satisfaction of a product.

So basically it was an upgrade to the existing “usability” definition, with the addition of two new components:

  1. Learnability: the product usability can be learned by the user
  2. Retainability: the product usability an be retained by the user.

Basically the addition of the above two components gave rise to the concepts of “mental model” of the user and it’s role in usability.

System Models

During 1980–90’s many “system models” evolved. These models were actually representation of a system from different stake holders’ perception, namely: the user, the programmer and the designer.

Fig: 7

Among the evolved models, the most notables were that of Norman , Cooperand IBM:

  1. The model based on the programmer’s perception:
     This was the way that a system works from the programmer’s perspective
  2. User’s Mental Model:
     The way that the user perceives that the system works.
  3. The model based on the designer’s perception:

The way the designer represents the program to the user, including presentation, interaction, and object relationships.

What is a “Mental Model” exactly?

A mental model is “a person’s intuition of how something works based on past experiences, knowledge, or common sense”. When you see a book you already know how to use it (i.e. read it) as this understanding of usage of a book is bound with your past experience and the expectation aroused there by using the the book. This typical expectation of how a thing works or the expectation regarding the workflow of an object the user faces is all about a “mental model”. When it is the case of an online experience, or a software usage, users expect a certain flow based on both previous experiences, and an expectation on what the experience should be. Understanding and catering to this kind of user’s expectation in an intuitive manner is the most critical part of the UX design process.

During “usability testing” of a software product, it is measured against the following five important facets:

  1. Useful:if the product enables users to solve real problems in an acceptable way and as a practical utility whether it supports the user’s own task model.
  2. Findable: if user can find what he is looking for through his interaction with the system.
  3. Accessible:if the system can be used by persons with some type of disability such as visual, hearing and psycho-motor.
  4. Usable:if system enables users to solve real problems in an acceptable way
  5. Desirable: if the user is emotionally motivated to use the system
  6. Meaningful: It must improve the value and customer satisfaction to be more meaningful in the context.

On a close look it is clear that all of these are all related to the users’ expectations. If any of these aspects do not match the expectations of the users, the usability of the product/system decorates. So, in UX design process, the most important task is to match or at least bring the design closer to the mental model of the users.

One of the best definition about mental models as they relate to software and usability can be found out in a 1999 article by Davidson, Dove, and Weltz titled Mental Models and Usability:

For most cognitive scientists today, a mental model is an internal scale-model representation of an external reality. It is built on-the-fly, from knowledge of prior experience, schema segments, perception, and problem-solving strategies. A mental model contains minimal information. It is unstable and subject to change. It is used to make decisions in novel circumstances. A mental model must be “runnable” and able to provide feedback on the results. Humans must be able to evaluate the results of action or the consequences of a change of state.

Most-likely Mental Model

The problem with matching the interface design and system flow with the mental model of the users is that :

  1. There is no fool proof approach that can provide insight into the target users’ mental models
  2. Different users have different mental models. Different users have different perceptions, past experiences, there by their mental models are most likely not the same.

In real life, an interface will never match up with every mental model because the number of possible models ranges from one to millions. So the trick is to create interfaces to match the most-likely mental models for the target users.

To determine what can be the criteria of a most likely mental model, typically different user personas, research, prototyping and user testing tools and methodologies are used.

Conceptual Model

“Conceptual Model” is a term used to represent the engineered interface that is provided to the user. For example, we can think about iBooks app on an iPad as a conceptual model being offered to the user

Fig : 9

To make UX successful, the “conceptual model” is designed to come close to the “mental model”.

If the user has read/seen any physical book, then in this case it will be easy for him to use iBooks app as it’s interaction approach is similar to a real life book where the user can turn pages to read. However iBooks has been designed by some engineer that presents a similar experience to the real book . This conceptual model in this case matches with the expectations of the user who has never interacted with the app,but has some preconceptions regarding it .His mental model about the app is formed from his past experience of interacting with the real physical book.

Challenges in Usability Measurement and Metrics

All the models and facets of usability described above have some limitations as it is not straight forward to implement them to some kind of metrics by which the usability goals can be measured. This is mostly because, there is comparatively little information about exactly how to select a set of usability factors to form a metrics to measure in the context of a software development lifecycle having aspects such as business needs and goals, management objectives, resource limitation on product development.

Even though in generic terms “usability” refers to a set of multiple concepts, such as execution time, performance, user satisfaction and ease of learning (“learnability”), taken together, it is still not been defined homogeneously to a level useful for creating a fool-proof metrics.

A challenge with definitions of usability is that it is very difficult to specify what its characteristics and its attributes should be, in particular because the nature of the characteristics and required attributes depend on the context in which the product is used. (Alain Abran et. al. , 2002)

For such reasons there is always a scope to create a consolidated usability model and its factors that can work for creating a metrics useful for software development life cycles.

A List of Factors for Generic and Consolidated Usability Model

As discussed above, here is a very generic consolidated usability model that can be used to create a metrics for a practical usability review.

The suggested model covers most of the commonly reviewed “factors” of different software products and systems which can be customized depending on the context or the need of the project:

  1. Effectiveness:This factor can be used to measure if the user is able to complete the tasks on product or the system (e.g. a website).
  2. Efficiency:It measures if the user is able to carry out the tasks, accurately and quickly.
  3. Findable: if user can find what he is looking for through his interaction with the system.
  4. Expectations: this measures if the user mental model matches with the conceptual model offered through the system.
  5. Emotions: This measures how the user feels while and after using the system .
  6. Satisfaction/ Experience:This measures if the overall system usage for the user is positive and if the user would like to revisit/reuse the system in case of the need (or will he look for alternatives).This is basically the subjective responses from users about their feelings when using the system.
  7. Productive: This measures if the amount of useful output that is resulted from user interaction with the system.
  8. Learnability: This measures how easy it for the user to master the usage of the functionalities.
  9. Safety: It measure the level of safety of the user and his information during and after the period of operation
  10. Accessibility:It measures capability of the system to be used by persons with some type of disability such as visual, hearing and psychomotor.
  11. Usefulness:It measure is the product enables users to solve real problems in an acceptable way and as a practical utility whether it supports the user’s own task model.
  12. Universality: It measures if the system has universal appeal and enables the users from diverse cultural backgrounds and locale.
  13. Trustfulness:This specially measures if the user trusts the system for critical usage (such as using credit cards on an e-commerce site)
  14. Meaningfulness:It must improve the value and customer satisfaction to be more meaningful in the context..

Based on the above factors, usability metrics can be prepared to conduct usability testing on the system.

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© 2013–14, Samir Dash

This article is a part of the title UX Simplified: Models & Methodologies by Samir Dash (ISBN: 978–1–3115–9110–4 / ASIN: B00LPQ22O0 )