Editing Usability (section)

===Cognitive modeling methods===
Cognitive modeling involves creating a computational model to estimate how long it takes people to perform a given task. Models are based on psychological principles and experimental studies to determine times for cognitive processing and motor movements. Cognitive models can be used to improve user interfaces or predict problem errors and pitfalls during the design process. A few examples of cognitive models include:

====Parallel design====
With parallel design, several people create an initial design from the same set of requirements. Each person works independently, and when finished, shares concepts with the group. The design team considers each solution, and each designer uses the best ideas to further improve their own solution. This process helps generate many different, diverse ideas, and ensures that the best ideas from each design are integrated into the final concept. This process can be repeated several times until the team is satisfied with the final concept.

====GOMS====
{{main|GOMS}}
''GOMS'' stands for ''goals, operators, methods, and selection rules''. It is a family of techniques that analyzes the user complexity of interactive systems. Goals are what the user must accomplish. An operator is an action performed in pursuit of a goal. A method is a sequence of operators that accomplish a goal. Selection rules specify which method satisfies a given goal, based on context.

====Human processor model====
{{main|Human processor model}}
Sometimes it is useful to break a task down and analyze each individual aspect separately. This helps the tester locate specific areas for improvement. To do this, it is necessary to understand how the human brain processes information. A model of the human processor is shown below.

[[File:HumanProcessorModel.svg]]

Many studies have been done to estimate the cycle times, decay times, and capacities of each of these processors. Variables that affect these can include subject age, [[aptitude]]s, ability, and the surrounding environment. For a younger adult, reasonable estimates are:

{| class="wikitable"
|-
! Parameter
! Mean
! Range
|-
| Eye movement time
| 230 ms
| align="right" | 70–700 ms
|-
| Decay half-life of visual image storage
| 200 ms
| align="right" | 90–1000 ms
|-
| Perceptual processor cycle time
| 100 ms
| align="right" | 50–200 ms
|-
| Cognitive processor cycle time
| 70 ms
| align="right" | 25–170 ms
|-
| Motor processor cycle time
| 70 ms
| align="right" | 30–100 ms
|-
| Effective working memory capacity
| 2 items
| align="right" | 2–3 items
|}

Long-term memory is believed to have an infinite capacity and decay time.<ref>Card, S.K., Moran, T.P., & Newell, A. (1983). ''The psychology of human-computer interaction''. Hillsdale, NJ: Lawrence Erlbaum Associates.</ref>

====Keystroke level modeling====
{{main|Keystroke level model}}
Keystroke level modeling is essentially a less comprehensive version of GOMS that makes simplifying assumptions in order to reduce calculation time and complexity.