RESUMO
Two problems have been dealth with: a) are rats able by self-learning to form purposive associations, involving elements of reasoning object activity and b) at what age period are they most capable of purposive tool activity. The experiments were performed on 55 rats aged from two to three, five to six and eight to ten months. It was established that tool activity in rats appeared on the 14th to 34th experimental day in 14.5% of all the experimental animals. By age groups the activity was distributed as follows; at the age of two to three months the problem presented was solved by 10% of the individuals, at five to six months -- by 30% and at eight to ten months, by 0%. Thus tool thinking as one of the forms of animals' higher adaptation to surroundings, is inherent not only in anthropoids but in species much lower in the evolutionary scale. By the form of its realization thinking activity in rats is less plastic than in apes and in our experimental conditions, it was not exhibited by all the rats.
