This field-portable reaction time test and analysis software run on devices using the Palm operating system. It is designed to emulate a test and commercial device widely used in sleep deprivation, shift work, fatigue, and stimulant drug research but provides additional capabilities. Experimental comparisons with the standard commercial device in a 40-hour total sleep deprivation study show it to be comparably sensitive to selected experimental variables. A Pocket PC-compatible version is under developement.
Changes in maximal saccadic velocity (SV), initial pupil diameter (IPD), constriction latency (CL) and constriction amplitude (CA) determined by the pupillary light reflex have been found to be sensitive indicators of impairment as a result of drugs, sleepiness, and/or fatigue. Ambient illuminance and time of day are controlled when these indices are applied as repeated measures in fitness-for-duty determinations. The application of oculometrics in unrestricted operational environments, where ambient illuminance and time-of-day testing are not constant, requires understanding of, and potential compensation for, the effects of, and interactions among, these multiple uncontrolled variables. SV, IPD, CL, and CA were evaluated in the morning and evening on two consecutive days following adequate nightly sleep under one baseline ambient illuminance and seven test ambient illuminances. Sixteen healthy volunteers (21-38 years, eight females/eight males) participated. Within and across days, SV was unaffected by decreasing ambient light or time-of-day effects. With the increase of ambient light from 670 to 3300 lx, CL decreased by 1%, while IPD and CA decreased by 17% and 20%, respectively. IPD increased with time of day by 1-10% (IPD was smaller in the morning). The results show that SV and CL are essentially resistant to changes in ambient light and time-of-day effects, simplifying their application in uncontrolled operational environments.
Information from this effort, specifically the reliable change parameters and the base rates of reliable decline, can be used to assist with the identification of postdeployment cognitive issues.
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