Performance-Based
With
performance-based measures, a portion or all of a user's task is
selected for objective and quantitative measurement. Traditionally,
performance-based measurements have included speed and accuracy
data. Speed can be reaction time either to perceive an event or
to initiate a response. Accuracy can be whether or not a signal
is perceived and if an appropriate response is made. Sometimes a
secondary task measure is introduced in order to determine if spare
performance capacity exists.
- Primary
Task Measure - This is usually the most important component
of a particular job or a job component that is suspected of unduly
increasing workload. Primary task measures are used to discriminate
cognitive overload from non-overload conditions. These measures
are particularly useful in assessing design options to determine
if user performance is acceptable.
- Secondary
Task Measure - Secondary tasks are measured to determine
if reserve cognitive and performance capacity is available in
addition to primary task performance. These measures are used
to evaluate the potential for overload conditions among design
options.
|
Secondary
Tasks Determine Reserve Capacity |
Performance-based
measures can be selected and instrumented so as to be non-intrusive
to the user. However, it is difficult to take such measures in some
environments such as in the cockpit or in air traffic control operations.
Therefore, such measures tend to be used with prototypes or simulators.
For this reason, it may be difficult to use performance measures
in early design phases.
|