No abstract

The effects of information processing on pupil diameter were investigated. Results showed that pupil diameter was significantly greater than a baseline diameter when Ss were required to process information at 75 and 100% of their maximum capacity. However, when Ss were required to process information at a rate above their maximum capacity, the pupil constricted significantly below the baseline diameter. Pupil diameter may be a parameter which would identify points in time where mental overload occurs in a worker's job, and therefore identify areas of the job which should be redesigned if one wished to reduce mental overload.

Naval Postgraduate SchoolStimmary.-The purpose of this study was to examine the effects on the perceptual processes when the contours of a map are layer tinted with various colors. Data from military officers serving as Ss indicated layer tinting significantly reduced the times to determine altitudes of specific locations on a map. However, layer tinting had a detrimental effect and significantly increased times to determine grid coordinates on the same map.

to 5. Another possibility is that the presence of short intervals in the series somehow interfered with the ability to maintain a set over longer periods. However, this alternative explanation suffers from the absence of a statistically significant three-way interaction. In other words, one might have expected the deterioration in performance under the long Pis to have been more evident when there was a relatively high proportion of short Pis. REFERENCES KAELIN. L. Reaction time as a function of foreperiod duration and variability.

A three-group experiment was performed to evaluate the effect of a secondary task of simple mental arithmetic on visual monitoring performance. The primary task was detection of a slightly larger excursion of a voltmeter needle making 50 uniform excursions per minute. The length of the vigil was 48 min., during which 32 signals were presented. The time-sharing group (T) performed, in addition to the monitoring task, a secondary task of adding two one-digit numbers presented auditorally 3 times a minute. Two control groups, one with the numbers presented (N) and one with only random noise (C), performed only the monitoring task. Results showed no difference in detection rate between groups, but a significant time decrement ( p < .001) and no group-by-time periods interaction. Commissive errors were significantly higher in the time-sharing group than the control groups. The results are seen as contrary to the arousal theory of vigilance.