[Limits to formation of trace conditioned reflexes to time].

Conditioned reflexes to different time intervals (from 0.25 to 90 min) were elaborated in Wistar line rats by motor food-procuring method. A conditioned reflex to time is formed easier and attains highest precision to intervals from 1 to 4 min. With shorter (0.5 to 0.75 min) and longer (6 to 10 min) intervals, the reflex to time is unstable and not precise. To intervals beyond the 0.5 to 10 min range the conditioned reflex to time could not be formed by the above method. Experimental data are corroborated by theoretical estimations of the shortest and longest intervals to which it is possible to elaborate a conditioned reflex to time by trace reflex mechanism. The data obtained are considered as a confirmation of Pavlov's hypothesis on the physiological mechanisms of the process of formation of a short-interval conditioned reflex to time.