AAWSAP DIRD, Cognitive Limits on Simultaneous Control of Multiple Unmanned Spacecraft, December 2010

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and a quantitative scale, allowing it to be used in threshold detection and prediction, as
well as in computer-assisted workload balancing.
PERFORMANCE MEASURES
Laboratory, reaction time to an event stimulus is a typical real-time measure of speed.
Outside the laboratory, in a more natural environment, speed is an indirect measure of
a subject's ability to keep up with a given rate of events. a Accuracy is measured in
both the laboratory and naturalistic environments: for example, in an air-traffic control
task, properly handing off a plane to the next controller, as it leaves the first
controller's monitored airspaceb, is measured as a successful task completion.
Performance, when utilizing a secondary task, is accomplished following two paradigms.
First, in the dual-task paradigm, performance on the secondary task is required and
primary task performance is thus an indication of workload. For the second paradigm,
instruction is given to maintain the primary task performance, and performance on the
secondary task is thus a measure of "space capacity" for additional workload.
Care is required in selection of secondary tasks in order to ensure they affect the
resources one wishes to probe. For example, in a driving scenario, a minimally
intrusive task is to push a button on the floor or steering wheel when a light flashes in
the field-of-view of the driver. This visual "detect-and-respond" task adds to what is
primarily a complex visual and motor coordination task that probes the capacity of
visual attention.6 This is different than a secondary task utilizing different resources,
such as having a conversation while driving. When planning the paradigm, a model
needs to be developed that treats (or explicitly ignores) individual tasks and
interactions among them.
Reference tasks are executed before and after primary tasks. Typically reference tasks
focus on trending in performance due to effects such as fatigue. One important case of
reference tasks is to normalize an individual's current capacity for mental workload.
Such a pre-performance measure can be used to adjust maximum workload to
compensate for day-to-day variation.
PHYSIOLOGICAL MEASURES
The human nervous system is anatomically divided into the Central Nervous System
(CNS) - and the Peripheral Nervous System (PNS). The CNS includes the brain and the
spinal cord. The PNS is made up of the somatic division, which innervates the skin,
voluntary muscle, and joints, and the autonomic division, which mediates visceral
sensation as well as executes motor control of smooth muscle, viscera, and endocrine
glands. The autonomic division consists of sympathetic, parasympathetic, and enteric
systems. The sympathetic system mediates response to stress, while the
parasympathetic system works to maintain homeostasis and conserve body resources.
• Reaction time is not typically measured in real-time in the field as events occur at unplanned times. Post-hoc
analysis can resolve reaction times down to a comparable resolution to innate motor reaction variance, on the
order or lO's of msec.
b Contrary to what a layperson may think, the vast majority of errors in air traffic control do not result in collisions
or even near misses; rather they are mistakes In procedure.
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