The ABCs of UX: The Diverse Disciplines (Part 3/3)

The current post is the 3rd 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).

 

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 psychomotor.
  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.

 

 

Fig : 1

 

 

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 interfacedesign 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: 2

 

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 measureshow 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 ecommerce 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.

 

(c) 2013-14, Samir Dash

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