Effects of red light and loud noise on the rate at which monkeys sample the sensory environment.

Monkeys, given the opportunity to move between two featureless chanbers, 'sample' first one, then the other in a way which reflects a Poisson decision process. The rate of sampling is higher in red light than in blue and in loud noise than in quietness. We suggest that monkeys 'tune' their sampling rate to the a priori probability of change in the environment.

Do monkeys' subjective clocks run faster in red light than in blue?

When monkeys are given control of the illumination in a testing chamber, it has been found, under three conditions, that they spend less time with red light than with blue. But the results cannot easily be explained in terms of 'preference'. Rather, the results suggest that monkeys judge 'subjective time' to pass nearly twice as fast in red light as in blue.

How monkeys acquire a new way of seeing.

In an experiment on perceptual learning, monkeys were given the opportunity to watch on television the "private behaviour" of another monkey (which did not know it was being watched.) The subjects were shown monkey X for twenty sessions in a row, followed by monkey Y for twenty sessions, followed by monkey X again fro twenty sessions. The subjects' "interest" in the stimulus monkey remained roughly level within each block of twenty sessions, but increased in a step-like way at the changeover from X to Y, and again from Y to X. These results are interpreted as evidence that the subjects gained little or no extra insight into the nature of private behaviour through watching the same monkey in successive sessions; the critical factor in their perceptual education was the comparison between one monkey's behaviour and another's.