HUMAN INFORMATION
PROCESSING
Human Information Processing
Predictive Performance Assessment: GOMS (Goals,
Operators, Methods and Selection)
• Many Important Cognitive Activities has been
analyzed in terms of their typical approximate
process time; for single-chunk retrieval from shortterm memory, encoding (memorizing of information
into the long-term memory, responding to a visual
stimulus and interpreting it’s content, etc.
Human Information Processing
Table 3.1 and 3.2 illustrate such an example based on the framework
called GOMS ( Goals, Operators, Methods, and Selection).
Table 3.1 Estimate of Time Taken for Typical Desktop Computer Operations from GOMS
TYPES OF OPERATIO
K: Keyboard input
Time ESTIMATE
Expert: 0.12 s
Average: 0.20 s
Novice: 1.2 s
T(n): Type n characters 280 x n ms
280 x n ms
P: Point with mouse to something on the
100 ms
display
B: Press or release mouse button
100 ms
Human Information Processing
BB: Click a mouse button (press and release)
200 ms
H: Home hands, either to the keyboard or mouse
400 ms
M: Thinking what to do (mental operator)
1200 ms
(can change)
W(t): Waiting for the system (to respond)
tms
Human Information Processing
Table 3.2 Estimate of Time Taken for Two Task Models of “Deleting a File”
DELETING A FILE
DESIGN 1
1. Point to file icon
2. Click mouse button
3. Point to file menu
4. Press and hold
mouse button
5. Point to DELETE item
6. Release mouse button
DESIGN 2
P
BB
P
B
P
B
1. Point to file icon
P
2. Click mouse button
BB
3. Move hand to keyboard M
4. Hit command key;
KK
command-T
5. Move hand back to mouse H
Human Information Processing
7. Point to original window
Total time= 4.8 s
P
Total time= 2.66 s
Note: The total time is computed by adding the corresponding figures
in Table 3.1. Design 2 is the “expert” version that uses a hot key [7].
The original GOMS model was developed mainly for
the desktop computing environment, with performance
figures for mouse clicks, keyboard input, hand
environment, and mental operators.
Human Information Processing
GOMS is quiet simple in that it can only evaluate in
terms of the task performance, while there are many
other criteria by which an HCI design should evaluate.
Sensation and Perception of Information
 The processes of sensation and perception in the
four major modalities and the associated human
capabilities in this regard.
Just as cognitive science was useful in information and
the task modeling, this knowledge is essential in sound
Human Information Processing
interface selection and design.