Thesis

Effects of illumination, stimulus modality and interval duration on time estimation

A study was conducted to investigate the effects of stimulus modality, amount of illumination, and length of duration on time estimation in humans. Twelve male and 12 female subjects were exposed to conditions consisting of either auditorially or visually defined temporal intervals under one of three lighting levels: dark (less than .33 lux), low (86 lux) and high (170 lux) intensity and then asked to estimate a series of durations, varying in length, by the method of reproduction. The illumination dimension was intended to replicate the findings of Delay and Richardson (1981), the first study to test the effect of illumination on time estimation using human subjects. In addition, durations of varying lengths were included in order to generalize results to durations other than those in Delay and Richardson's (1981) study. Contrary to the hypothesis, illumination was not found significantly to effect time estimations. For this sample, auditorially defined intervals were judged to be longer than visually defined intervals, but this effect was not statistically significant. Significant effects were produced for duration and the duration by modality interaction. Subjects’ accuracy of estimates in the auditory condition were affected by a change in duration length but subjects’ estimates in the visual condition were not. Generally, estimates were consistent with Vierordt's Law of regression to the arithmetic mean of the durations. A tentative model was proposed linking the physiological factors in Treisman’s (1963) model of the internal clock with Hocherman and Ben-Dov’s (1979) cognitive based hypothesis involving the mediation of temporal processing by specific sense mode sites.

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