Human processor model

Human processor model is a cognitive modeling method used to calculate how long it takes to perform a certain task. Other cognitive modeling methods include parallel design, GOMS, and KLM (human-computer interaction). Cognitive modeling methods are one way to evaluate the usability of a product. This method uses experimental times to calculate cognitive and motor processing time. The value of the human processor model is that it allows a system designer to predict the performance with respect to time it takes a person to complete a task without performing experiments. Other modeling methods include inspection methods, inquiry methods, prototyping methods, and testing methods.

The human processor model uses the cognitive, perceptual, and motor processors along with the visual image, working memory, and long term memory storages. A diagram is shown below. Each processor has a cycle time and each memory has a decay time. These values are also included below. By following the connections diagrammed below, along with the associated cycle or decay times, the time it takes a user to perform a certain task can be calculated. Studies into this field were initially done by Card, S.K., Moran T.P., & Newell, A. Current studies in the field include work to distinguish process times in older adults by Tiffany Jastrembski and Neil Charness (2007).

Parameter	Mean	Range
Eye movement time	230 ms	70-700 ms
Decay half-life of visual image storage	200 ms	90-1000 ms
Visual Capacity	17 letters	7-17 letters
Decay half-life of auditory storage	1500 ms	90-3500 ms
Auditory Capacity	5 letters	4.4-6.2 letters
Perceptual processor cycle time	100 ms	50-200 ms
Cognitive processor cycle time	70 ms	25-170 ms
Motor processor cycle time	70 ms	30-100 ms
Effective working memory capacity	7 chunks	5-9 chunks
Pure working memory capacity	3 chunks	2.5-4.2 chunks
Decay half-life of working memory	7 sec	5-226 sec
Decay half-life of 1 chunk working memory	73 sec	73-226 sec
Decay half-life of 3 chunks working memory	7 sec	5-34 sec

See also

• GOMS
• KLM (human-computer interaction)

References

• Lui, Yili; Feyen, Robert; and Tsimhoni, Omer. Queueing Network-Model Human Processor(QN-MHP): A Computational Architecture for Multitask Performance in Human-Machine Systems. ACM Transactions on Computer-Human Interaction. Volume 13, Number 1, March 2006, pages 37-70.
• Card, S.K; Moran, T. P; and Newell, A. The Model Human Processor: An Engineering Model of Human Performance. In K. R. Boff, L. Kaufman, & J. P. Thomas (Eds.), Handbook of Perception and Human Performance. Vol. 2: Cognitive Processes and Performance, 1986, pages 1–35.
• Jastrzembski, Tiffany; and Charness, Neil. The Model Human Processor and the Older Adult: Parameter Estimation and Validation within a Mobile Phone Task. Journal of Experimental Psychology: Applied. Volume 13, Number 4, 2007, pages 224-248.