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Human Computer Interaction Notes
2nd December 2009

These notes are based around my COMP3511 course.

Interaction Design (+Scenarios)

Cooper et al. describe the process of interaction design as,

  1. Identifying needs and establishing requirements for the user experience.
  2. Developing alternative designs that meet those requirements.
  3. Building interactive versions of the designs so that they can be communicated and assessed.
  4. Evaluating what is being built throughout the process and the user experience it offers.

Scenarios are narratives about named people with an age. We need some background to understand where they are coming from (for instance their cultural background (eg. the US uses MM/DD/YYYY but Australia uses DD/MM/YYYY)). We try to remove incorrect assumptions about what we think a certain group of people are like. The scenario should explain their motivations and their goals.

Usability

Usability is all about producing things which are usable. Where something is usable when it meets these usability goals, however you should work out which goals are most important for the problem and focus on those first.

Usability Goals

User Experience Goals

Heuristics (Usability Principles)

Design Principles

When designing a system we need to consider,

Identifying Needs

Requirements

When testing an interface with users/test participants, give them a high level goal and observe how they go about doing it. Don't give them specific instructions.

Use Scenario 1: For each task identified (or major tasks, or particularly special tasks if many tasks are defined), write a description of how that user would accomplish the task independent of how they would complete it within the application.

Use Case 1: If a use scenario has been implemented, include a matching use case which describes how the task use scenario can be completed in the application. There may be branching or multiple ways to complete the task, and this is a good way to document it.

To test if something is a requirement just ask, "If I remove this, will the product still fulfil its purpose?"

Design Conceptualisation

A conceptual model is a high-level description of how a system is organised and operates. --Johnson and Henderson, 2002, p. 26

I like to think of it as this. The person coding the web browsers understands that when the users types in a URL and presses enter an HTTP GET request is sent and the response is received and the HTML is processed and displayed. There are many technical interactions and details that are happening here. But the conceptual model of this is what the average non-technical uses thinks is happening. They just have some kind of model in their head that they type the URL hit enter and get the web site displayed. Its just an abstraction of what is going on.

Interface metaphors are used as they can help the user understand and determine how an interface works. We try to use them for this purpose but just using the metaphor directly can have some negative affects (eg. if your designing a radio application for desktop PC's, it may not be a good idea to just show an image of a real radio as the UI). We don't want to use the metaphor to an extent that it breaks the design principles.

A classic example of a conceptual framework is that of the relation between the design of a conceptual model and the user's understanding of it. In this framework there are three components, (Sharp et al., 2006)

[caption id="attachment_772" align="aligncenter" width="361" caption="Conceptual Framework (from Norman, 1988)"]Conceptual Framework (from Norman, 1988)[/caption]

The designers job is to create the system image so that the users will invoke the same conceptual model as the designer's.

The interface could be made more transparent so the user can see the details of how the system works, but this is not always desirable as it may cause confusion. Also many users may not want to know all the gory details, nor should they have to know the actual implementation in order to use the system.

Prototyping

Using A Design Diary

Wireframes

Here is an example wireframe.

[caption id="" align="aligncenter" width="445" caption="Example Wireframe from https://wiki.ubuntu.com/DesktopExperienceTeam/KarmicBootExperienceDesignSpec"]Example Wireframe from (https://wiki.ubuntu.com/DesktopExperienceTeam/KarmicBootExperienceDesignSpec)[/caption]

Another paper prototype with a slightly higher fidelity.

[caption id="attachment_850" align="aligncenter" width="450" caption="An example paper prototype (from https://wiki.ubuntu.com/SoftwareStore)."]An example paper prototype (from https://wiki.ubuntu.com/SoftwareStore).[/caption]

Issues Table

Usability Testing

There are some legal and ethical issues to consider. The participant,

During a Usability Test,

After the Testing,

Usability Testing

When actually running a usability test you should follow a usability test plan. The test plan just details what the test facilitator should do during the test.

The usability testing procedures we used in this course are:

  1. Explain procedures (think aloud, data collection methods in use...)
  2. Make sure they agree and sign a consent for before proceeding (you keep one, they keep one)
  3. Run a pre-test questionnaire (used to generate a participant profile) (this helps to give you an idea on their experience level, as well as any background they may have in using similar interfaces before, as these affect how the participant performs) (best to get the participant to do this a few days before the test so that you can focus on specific tasks.)
  4. Introduce scenario
  5. Run through tasks
  6. Ask any post test questions
  7. Do they have any extra comments/debriefing
  8. Thank them for their time

Interviews

Questionnaires

User Centred Design Process

The UCD process is all about focusing on the users and tasks. It also means iterate your designs often. The development is driven by users needs rather than technical concerns.

More specifically Gould and Lewis (1985) give three principles,

Affinity Diagramming

Card Sorting

Software Lifecycles

Cognitive Load Theory

Cognition is what goes on in our brains. It includes cognitive processes such as,

Some Cognitive Load Theory

Some HCI Applications

Memory

(From a psychologists perspective).

Long Term Memory

 

[caption id="attachment_794" align="aligncenter" width="360" caption="A Taxonomy of Memory"]A Taxonomy of Memory[/caption]

Explicit and Implicit Memory

"Imagine that you learn a list of items and are then required to recall or recognise them. This memory test would be accompanied by conscious awareness that you were remembering. Imagine that a considerable time later, a test of recall or recognition revealed no memory for the items. However if you were given the original list to relearn there would probably be some savings in learning time (i.e. you would take less time to learn the list the second time, oven though you were not aware of your memory of the items). This is the distinction between explicit memory, in which remembering is accompanied by either intentional or involuntary awareness of remembering, and implicit memory, in which remembering is not accompanied by awareness (Graf & Schacter 1985; Schacter 1987)." -- (Walker, "Chapter 9: Memory, Reasoning and Problem Solving". pg. 262 (sorry I don't have the title))

Not really related, but a good thing to hear a text book say,

"Finally, some long-enduring memories are for passages that our teachers have drulled into us... The Interesting thing about these memories is that they are preserved as they were memorised, in a very literal form, in exact wordings (Rubin, 1982). The memory code is not transferred from literal to semantic. In fact, the words are often remembered mechanically, with almost no attention to their meaning." --(Walker, "Chapter 9: Memory, Reasoning and Problem Solving". pg. 267 (sorry I don't have the title))

Obstacles to Problem Solving

External Cognition

People use external representations to extend or support ones ability to perform cognitive activities. For example, pens and paper, calculators, etc. We do this to,

  1. reduce memory load
    • eg. post-it notes, todo lists. But the placement of say post-it notes is also significant.
  2. offload computation
    • eg. pen and paper to solve a large arithmetic problem (the mechanical kind).
  3. annotate
    • modifying or manipulating the representation to reflect changes

Experts vs. Novices

Visual Design

Internationalisation

Differences around the world,

Internationalisation (i18n) refers to designing and developing a software product to function in multiple locales. Localisation (L10n) refers to modifying or adapting a software product to fit the requirements of a particular locale. This could include translating text, changing icons, modifying layout (eg. of dates).5

A locale is a set of conventions affected or determined by human language and customs, as defined within a particular geo-political region. These conventions include (but are not necessarily limited to) the written language, formats for dates, numbers and currency, sorting orders, etc.5

Accessibility

Quantification

GOMS

Keystroke Level Model

Fitt's Law

References

[1] Sharp, Rodgers, Preece. (2006) Interaction Design: Beyond human computer interaction. 2nd Ed.

[2] Marcus, Nadine. (2009) COMP3511 Cognitive Load Theory Lecture Slides.

Woo, Daniel. (2009) COMP3511 Lecture Slides.

Norman, Donald. (1988) The Design of Everyday Things.

[5] http://www.mozilla.org/docs/refList/i18n/

Tags: comp3511, computing.

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