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Human Computer Interaction Cognitive Models

Cognitive models attempt to represent how users think as they interact with interfaces. They model aspects of a user's understanding, knowledge, intentions, and mental processing. Goals represent what a user wants to achieve, while tasks are the actions to achieve goals or subgoals. Techniques like GOMS (Goals, Operators, Methods, Selection) use hierarchies to break goals down into subgoals and tasks. GOMS models decompose a goal into methods consisting of subgoals and basic operators. Selection rules determine which method to use based on conditions. Cognitive Complexity Theory also uses production rules and networks to model user cognition.

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815 views12 pages

Human Computer Interaction Cognitive Models

Cognitive models attempt to represent how users think as they interact with interfaces. They model aspects of a user's understanding, knowledge, intentions, and mental processing. Goals represent what a user wants to achieve, while tasks are the actions to achieve goals or subgoals. Techniques like GOMS (Goals, Operators, Methods, Selection) use hierarchies to break goals down into subgoals and tasks. GOMS models decompose a goal into methods consisting of subgoals and basic operators. Selection rules determine which method to use based on conditions. Cognitive Complexity Theory also uses production rules and networks to model user cognition.

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vicky aroora
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Human Computer Interaction

Lecture 23

Cognitive Models
Cognitive Models

Cognitive models claim to have some representation


of users as they interact with an interface, that is
they model some aspects of the user’s:
understanding, knowledge, intentions or mental
processing.
Level of representation differs from technique to
technique.
Goals vs. Tasks

Goals – intentions
what you would like to be true.
Goals can be divided into sub-goals.

Tasks – actions
how to achieve the goal or sub-goals.
Task can also be divided into sub-task or
smaller tasks(task analysis)
Goal and task hierarchies
Mental processing as divide-and-conquer
Example: sales report
produce report
gather data
. find book names
. . do keywords search of names database
. . . … further sub-goals
. . filter through names and abstracts by hand
. . . … further sub-goals
. search sales database - further sub-goals
layout tables and histograms - further sub-goals
write description - further sub-goals
Techniques (Models)

Cognitive models are classified as below:


Hierarchical models
• GOMS(Goals, Operators, Methods, Selection)
• Cognitive Complexity Theory (CCT)
Linguistic and grammatical models
• BNF (Backus-Naur Form)
• Task-Action Grammar (TAG)
Physical and device-level models
• Keystroke-Level Model
• Three State Model
 
GOMS
Goals
what the user wants to achieve

Operators
basic actions user performs

Methods
decomposition of a goal into subgoals/operators

Selection
means of choosing between competing methods
GOMS Example-1
GOAL: CLOSE-WINDOW
. [select
Sub GOAL: USE-MENU-METHOD
. MOVE-MOUSE-TO-FILE-MENU
. PULL-DOWN-FILE-MENU
. CLICK-OVER-CLOSE-OPTION
Sub GOAL: USE-CTRL-W-METHOD
. PRESS-CONTROL-W-KEYS]

For a particular user:

Rule 1: Select USE-MENU-METHOD unless another


rule applies
Rule 2: If the application is GAME,
select CTRL-W-METHOD
GOMS Example-2
Goal: delete a word in a sentence
Method-1 for accomplishing goal of deleting a word using
menu option:
Step1. Recall that word to be deleted has to be
highlighted
Step2. Recall that command is “cut”
Step3. Recall that the command “cut” is in edit
menu
Step4. Accomplishing goal of selecting and executing
the “cut” command
Step5. Return with goal accomplished
GOMS Example-2
Method-2 for accomplishing goal of deleting a word using
delete key:

Step1. Recall where to position cursor in relation to


word to be deleted
Step2. Recall which key to delete each letter
Step3. Press “delete” key to delete each letter
Step4. Return with goal accomplished
GOMS Example-2
Operators to use in above methods:

1.Click mouse
2.Drag cursor over text
3.Select menu
4.Move cursor to command
5.Press keyboard key
GOMS Example-2
Selection Rules to decide which method to use:

1: Delete text mouse and selecting from menu if large


amount of text is to be deleted

2: Delete text using delete key if small number of letters


are to be deleted
Cognitive Complexity Theory
• Cognitive complexity is the psychological
characteristic or variable that shows how complex or
simple the frame and perceptual skill of a person
are. It is the extent to which a person differentiates
and integrates an event.
• Two parallel descriptions:
– User production rules
– Device generalised transition networks

• Production rules are of the form:


– if condition then action

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