HUMAN TIME PERCEPTION IN TEMPORAL ISOLATION - EFFECTS OF ILLUMINATIONINTENSITY

Living in isolation from time cues under relatively high and low light intensities for a total (on average) of 24 days, 18 subjects estimate d the passage of time by ''producing'' short (10 to 120 seconds) and l ong (1h) intervals throughout the experiments. The 1h productions were independent of light intensity and highly positively correlated with the duration of wake times. The short-interval productions were marked ly increased under high light intensity. In a subsample of 6 subjects, the interaction between effects of body temperature and light conditi on on 10-second production was analyzed. Productions were negatively c orrelated with body temperature. In both dim and bright light, product ions decreased by a factor of 0.7 per degrees C. In bright light, prod uction was increased by a factor of 1.2 relative to dim light. This ef fect was not mediated by body temperature, which itself was on average slightly increased in bright light. Since subjective time is slowed b y bright light, objective time seems to pass faster in bright light.