On the perception of time during prolonged temporal isolation.
In an underground isolation unit, 42 subjects were living singly for time spans of at least 7 days up to more than a month. Except three who were entrained to 24 h by an externally controlled light-dark cycle (LD), subjects had no time cues and developed free-running circadian rhythms either in self-selected LD-cycles or in constant illumination. Each subject had to give a signal whenever he thought that 1 h had passed. In addition, 30 subjects produced short-time intervals within the range from 10 to 120 s.


RESULTS
The 1-h estimates were longer than 1 h, and had a strong positive correlation with the duration of wakefulness alpha as well as with the length of the circadian cycle. The short time estimates were equally distributed between under- and over-estimation of the required interval, and they were neither correlated with the 1-h estimates nor with alpha. It is concluded that long and short time estimates are based on different mechanisms.
D000293:Adolescent; D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D005260:Female; D005544:Forecasting; D006801:Humans; D008297:Male; D008875:Middle Aged; D012934:Social Isolation; D013223:Statistics as Topic; D013997:Time Factors; D013998:Time Perception; D014851:Wakefulness