0000000000328404
AUTHOR
Michael Juris
The pupillary response to mental overload
The hypothesis that the pupil constricts below base level in situations of mental overload was tested. Subjects had to perform in a four-alternative forced-choice task at 75%, 100%, and 125% the speed of their maximum processing capacity. No indication of a pupillary constriction in the overload situation was found. The pupil dilated under all three conditions. The pupil diameter of male subjects significantly decreased after the sharp increase at the beginning of the experimental phases, while the female subjects’ pupil diameter remained at the same level after the initial increase. The amount of dilation depended on information load for male subjects only. Results were taken as further in…
Perceptual Performance as a Function of Intra-Cycle Cardiac Activity
The purpose of the experiment was to test the hypothesis of a systematic change in perceptual performance within a single cardiac cycle due to the activity of the baroreceptors in carotid sinus. As an index of perceptual performance the ds-parameter from signal detection theory (TSD) was used. A 1000 Hz sine tone had to be detected in a background of white noise. Each of 4 subjects received on the average 4605 noise or noise plus tone stimuli distributed over 10 experimental sessions. When comparing performance during time intervals before and after baroreceptor activity onset no significant difference was found. Also, when tracing perceptual performance over the whole cardiac cycle in step…