Title page for ETD etd-02132009-171117
|Type of Document
||The effects of heat stress on operator perceived workload in tracking
||Master of Science
||Industrial and Systems Engineering
|Price, Dennis L.
|Casali, John G.
|Snyder, Harry L.
|Date of Defense
Eight male unacclimatized subjects were selected for the present investigation.
The subjects were all in excellent health and ranged in age between 25 and
35 years. Subjects performed one-dimensional horizontal compensatory tracking, the
Critical Instability Tracking Task (CITT), in each of eight environmental conditions for
an hour. Two levels of ambient temperature were used: 22°C (72°F) and 35°C
(95°F). Two levels of relative humidity were used: 45% RH and 80% RH. The resulting
Wet-bulb Globe Temperatures were 18°C (64°F) WBGT, 21°C (70°F) WBGT,
29°C (85°F) WBGT, and 34°C (93°F) WBGT. Two levels of tracking difficulty were
used: easy ()λlow = 1.0 and λhigh = 2.0) and moderate (λlow = 1.0 and λhigh = 5.0). Prior
research has demonstrated that both ambient temperature and tracking difficulty affected
significantly tracking performance (root-mean-square error) and perceived
workload (SWAT rating). However, in this study, hu midity did not affect either measure
significantly. This might be attributable to the upper bound of humidity (80% RH)
used in this research. Therefore, research needs to be done above 80% RH to examine
the effects of humidity in further detail. Results also indicated that the Subjective
Workload Assessment Technique (SWAT) can be used as a good indicator of
the actual changes in mental workload on tracking in heat. Finally, results showed
that tracking performance decrement occurred at a lower temperature (29°C (85°F) WBGT) than did the perception of significant mental workload on tracking (which occurred
at 34°C (93°F) W8GT).
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