[Learning characteristics and long-term memory in rhesus macaques].

The use of entropy of choices distribution in studying the processes of learning and long-term memory in rhesus monkeys during differentiation of periodic and non-periodic visual stimuli, showed that the transition from the unlearned state to the learned one proceeds not gradually but in two stages; the first stage--the accumulation of information and externally random behaviour, the second stage--rapid transition to the learned behaviour. For "filters" selective to spatial frequency, the change of stimuli orientation leads to an increase of the behaviour entropy. For "filters" selective to the bar width, the entropy practically does not change. During prolonged storage of acquired information, in the long-term memory, its partial loss takes place leading to an increase of the behaviour entropy. The difference between the entropy determined directly after the learning and that determined again after a prolonged storage of the memorized habit characterizes the quantity of information lost during the storage period.