What is a model human processor?
A model to describe human performance as it relates to human-computer interaction
What are the input, output and processing components in a MHP?
- eyes and ears are input
- arm-hand-finger for output
- brain for processors and memories
What are the 3 subsystems of the MHP?
- perceptual system
- motor sytem
- cognitive system
Perceptual system
- has perceptual memory and processor
- transforms external events into a form that the cognitive system can process
What is a perceptual memory?
A buffer for sensor data - raw images and sounds
What is the input and output of the perpetual processor
Stimuli turns into symbolic information
What is the cycle time for the perceptual processor?
100ms
What happens if more inputs are buffered in the perceptual memory that can be coded?
New inputs/sensations replace others in the memory
What affects the order of the info encoded by the perceptual processor?
What things we pay most attention to
What is the cognitive system?
- Contains long-term memory and the cognitive processor
- processes perceived information and decides how to act upon it
What does the cognitive processor do?
Works on symbolic information from perceptual coding
What is the cycle time of the cognitive processor?
70ms
What affects cognitive processing? (recognise-act cycle)
Recognise: Active associations stored in long-term memory
Act: decide what to do next
What is the difference between the processing of recognising and acting?
Recognise is done in parallel, while acting is serial (one at a time)
What is the uncertainty principle?
Decision time increases with uncertainty about the judgement to be made, requires more cognitive cycles
What can make cognitive cycle time shorter?
- Easier tasks
- greater effort
- practice
What does the motor system do?
translates thought into action
What is the cycle time of the motor processor?
70ms
what time of response is considered to be interactive in real time?
<0.01s
How does timing affect the user experience?
Influences perception of speed, responsiveness and control
Why is a shorter timing better for the UX?
less delays leads to less frustration and better efficiency
Why might a slower speed lead to a better UX?
makes the system seem more trustworthy e.g. a complex calculation or saving
