Cornell University Ergonomics Web
Cornell University Ergonomics Web
DEA 3250/6510 CLASS NOTES
Control-Display Compatibility
Control/Display Compatibility - Compatibility refers to the relationship
of stimuli and responses to human expectations.
1. Types of compatibility -
a. Conceptual Compatibility - degree to which codes and symbols correspond
to the conceptual associations people have, i.e. how meaningful codes and
symbols are to people who use them.
b. Modality Compatibility - degree to which the controls and displays
utilize the same sensory modality. Within-modality stimuli-response relationships
are generally faster, e.g. for verbal task auditory presentation and vocal
response is best, for spatial task a visual presentation and manual response
is best.
c. Movement Compatibility - relationships between movements of displays
and controls where the direction of movement of a control follows from expectations,
e.g. steering wheel turns car in direction of wheel movement.
Movement of a control can:
(1) follow - display movement as in radar tracking.
(2) control - display movement as when moving a computer mouse to
reposition a cursor.
(3) produce - a specific system response such as turning a
car steering wheel to turn a car in the same direction (it's the reverse
on a boat).
d. Spatial Compatibility - physical arrangement of controls and associated
displays in space or physical similarity of displays and controls.
2. Specific relationships
a. Rotary controls and rotary displays -
(1) Fixed scales and moving pointers - clockwise turn of pointer should
result from clockwise turn of control and should represent and increase
in the value.
(2) Moving scales and fixed pointers - scale should rotate in the
same direction as the control, scale numbers should increase from left to
right, and a clockwise turn should increase the setting. Unfortunately,
all three requirements can't be satisfied.
b. Rotary controls and linear displays in the same plane - controls
can be placed above, below, left or right of the display with fixed-scale
linear displays.
(1) Warricks' principle - the expectation is that the pointer on
a display will move in the same direction as the side of the control which
is nearest to it. This only applies when the control is located to the side
of the display.
(2) Scale-by-side-principle - the pointer will move in the same direction
as the side of the control that is on the same side as the scale markings
of the display. This applies to top and bottom control locations as well
as side locations and can conflict with Warrick's principle.
(3) Clock-wise for increase - clock-wise movement of a rotary control
will cause an increase in the value on the display irrespective of control
display relations.
(4) Clock-wise - away and Counter-clock-wise - near - clock-wise
rotation suggests movement away from a person and counter-clock-wise rotation
suggests movement towards the person.
c. Movements of displays and controls in different planes - relationships
tend to be orthogonal. Generally moving the control up and moving up on
the display is superior to moving the control up and moving down on the
display. There's less difference between moving the control forward to move
the display up and moving the control forward to move the display down.
d. Rotary and stick-type controls and linear displays - recommended
relationships are shown in the figures in the course text.
e. Rotary vehicular controls - Most vehicles don't have displays
reflecting the atual system output, rather the "display" is the response of
the vehicle.