20  Lecture 3: Understanding Users

20.1 Core Cognitive Aspects

The core cognitive aspects include

  • attention
  • perception and recognition
  • memory

20.1.1 Attention

Humans select things to concentrate on. This focused and divided attention enables us to be selective in terms of the mass of competing stimuli, but limits our ability to keep track of all events.

Design implications of attention include:

  • Information at the interface should be structured to capture users’ attention
  • Make information salient when it needs attending to
  • Use techniques to make things stand out like coloring, ordering, spacing, underlining, sequencing, and animation
  • Avoid cluttering the interface
  • Avoid using too much because the software allows it

20.1.2 Perception and Recognition

Perception and recognition is concerned with how information is acquired from the world and transformed into experiences

Design implication of perception and recognition include:

  • Design representations that are readily perceivable
    • Text should be legible
    • Icons should be easy to distinguish and read
  • Represetnations of information need to be designed to be perceptible and recognizable across different media, such as: icons, sounds, speech, and text

20.1.3 Memory

Involves encoding and recalling knowledge and acting appropriately. We don’t remember everything - involves filtering and processing.

A filtering process is used to decide what information gets further processed and memorized. Initially, encoding takes place, determining which information is attended to in the environment and how it is interpreted. The extent to which it takes place affects our ability to recall that information later. The context in which information is encoded also affects the extent to which information can be subsequently retrieved.

Memory involves 2 processes: recall-directed and recognition-based scanning

We recognize things much better than being able to recall things.

Design implication of memory include:

  • Don’t overlap users’ memories with complicated procedures for carrying out tasks.
  • Design interfaces that promote recognition rather than recall by using menus, icons, etc.
  • Provide a user with a variety of ways of encoding information (files, emails, image) to help them to remember where they stored them.

20.2 Mental Models

A successful system is one based on a conceptual model that enables users to readily learn a system and use it effectively. When people are leaning and using a system, they develop knowledge of how to use the system and how it works. These two kinds of knowledge are often referred to as a user’s mental model.

People tend to form different mental models for the same thing.

Notion of mental models have been used as basis for conceptual models.

Sometime people generalize the general value theory, ‘more is more’ principle, to different settings. This is bad.

20.3 External Cognition

External cognition is concerned with explaining how we interact with external representations, the cognitive benefits and processes involved, and how they extend our cognition.

Sometimes, we externalize to reduce memory load. Diaries, reminders, calendars, etc are all written to remind us of what to do. Post-its, piles, and marked emails indicates priority of what to do.

External representation:

  • Remind us that we need to do something
  • Remind us of what to do
  • Remind us when to do something

Computatinal offloading is when a tool is used in conjunction with an external representation to carry out a computation.

Annotation involves modifying existing representation through making marks (e.g., crossing off, ticking, underlining).

Cognitive Tracing involves externally manipulating items into different orders or structures (e.g, playing scrabble, playing cards).

Design implication for this include:

  • Provide external representations at the interface that reduce memory load and facilitate computational offloading
    • Example: Information visualization have been designed to allow people to make sense and rapid decisions about masses of data.

We can use knowledge about users to inform system design through:

  • Providing guidance and tools
    • Design principles and concepts
    • Design rules
  • Provide analytic tools
    • Methods for evaluating usability

20.4 Key Points

  • Cognition involves many processes including attention, memory, perception, and learning
  • The way an interface is designed can greatly affect how well users can perceive, attend, learn, and remember how to do their tasks
  • The conceptual framework of ‘mental models’ and ‘external cognition’ provide ways of understanding how and why people interact with products, which can lead to thinking about how to design better products.