[Probabilistic characteristics of "open field" behavior in the rat]

An analysis was made of the dynamics of probabilistic characteristics of the rat behaviour in the process of extinction of orienting-investigating behaviour in the "open field". Estimation of the entropy value related to behaviour permitted to divide the rats into two groups. The rats with high entropy values differed from those with low values by a more prolonged retention of a high level of locomotion, vertical stands, wall stands, peeping through a hole and grooming. It is suggested that a high entropy level and prolonged retention in the behaviour pattern of most of the elementary acts and poses may testify to a delayed process of extinction of orienting-investigating activity due to a higher level of the rats negative emotional state.