Cognitive frameworks, mental models and Norman's gulfs

Frameworks explain behaviour from inside and outside the head

Intuition

When someone cannot use your interface, either their picture of how it works is wrong, or the screen does not show what happened. Cognitive frameworks give you names for each failure so you can fix the right one.

Lecture 2 introduces cognitive frameworks to explain and predict user behaviour at the interface. They rest on theories of behaviour, focus on mental processes, and also look at the use of artefacts and representations. They split in two.

Compare

Internal frameworks

• Human information processing model
• Mental models
• Gulfs of execution and evaluation

External frameworks

• Distributed cognition: visualise propagation across representational states
• External cognition: tools to aid our limited cognition

The Model Human Processor (Card, Moran and Newell, 1986) was one of the first HCI models derived from information processing theory. Its application on the slide is model-based evaluation. Mental models are the user’s picture of how the system works. The slide is an image and gave no further text, so no definition beyond this is quoted. In the distributed cognition example, an order for a Big Mac at a drive-through moves from placing the order, to preparing the food (cook the patty, assemble), to giving the burger. Cognition is spread across people and artefacts.

The gulfs are two gaps between user and system

Mechanism

• Gulf of execution: the distance between the user’s goals and the means of achieving them through the system. Typical thoughts: “What do I do now?”, “How do I…?”, “I wanted to do X but cannot see how”, “Do I press this?”, “I am looking for X but cannot find it”.
• Gulf of evaluation: the amount of effort required to determine the system state. Typical thoughts: “What happened then?”, “What did I do wrong?”. A common behaviour is repeating the action, such as clicking Next or Submit again.

The extra slides give the same ideas in terms of direction. The gulf of execution is the distance from the user to the physical system. The gulf of evaluation is the distance from the physical system back to the user. Bridging the gulfs reduces the cognitive effort needed to perform tasks.

Optional aside

One Lecture 2 slide says “When problems occur in the evaluation phase, the gulf of execution widens”. That is likely a typo for the gulf of evaluation, since the same slide lists evaluation symptoms. This page treats evaluation problems as widening the gulf of evaluation.

Seven stages of action split across the gulfs

Norman’s seven stages model how a person completes an activity. All actions begin with a goal and are repeated until the goal is achieved. There are four stages of execution and three of evaluation.

Stage	Name	Question	Belongs to
1	Forming a goal	What do I want to achieve?	Execution
2	Forming the intention	What would satisfy this goal?	Execution
3	Specifying an action	What do I want to do to achieve the intention?	Execution
4	Executing the action	Do the steps I have specified	Execution
5	Perceiving the state of the world	Use my senses to gather information about the world or system	Evaluation
6	Interpreting the state of the world	Work out what, if anything, has changed	Evaluation
7	Evaluating the outcome	Did I achieve my goal?	Evaluation

Design implications for execution: transform goals into intentions and operating actions as easily as possible, make possible actions determinable in each situation, and make actions executable easily and robustly. For evaluation: the reaction of the system and its state are recognisable at all times and easily interpretable, and a displayed or indicated new state is easily comparable with the user’s goals.

Pitfall

Forming the goal is stage 1 of execution, not a separate stage. If a question gives a symptom, ask whether the user does not know what to do (execution) or cannot tell what happened (evaluation).

Try it: worked example

Worksheet W3 asks you to apply the seven stages to adding yourself to a project group on Canvas. Outline the stages.

Show answer and steps

AnswerGoal: be in a group. Execute: find People, then Groups, then Join. Evaluate: see your name listed.

1. Goal: I want to be in a project group.
2. Intention: join an existing group (rather than create one).
3. Specify the action: open the groups page and choose Join on a group.
4. Execute: click through the screens.
5. Perceive: look at the page after clicking.
6. Interpret: work out whether the page now shows you as a member.
7. Evaluate: goal achieved if your name appears in the group.
8. Gulf check: if you cannot find the groups page, that is execution. If the page does not clearly confirm membership, that is evaluation. The exact Canvas screens are not in the lecture, so this outline is illustrative.

Recall

Which seven-stage numbers are execution and which are evaluation?

Stages 1 to 4 are execution (goal, intention, specify, execute). Stages 5 to 7 are evaluation (perceive, interpret, evaluate).