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.