The pathway to the quantitative analysis of behavioral manifestations was opened by the research of Pavlov and his collaborators. The basic phenomenon that they investigated intensively was the conditional reflex, conditioning being the method devised to approach this problem. The postponement of the conditional reflex to the end of the prolonged conditional stimulation may be regarded as a retardation or delay, and the conditional reflex is called a retarded or delayed reflex. Conditional food reflexes were established. One of the dogs belonged to the strong and one to the weak type. A positive conditional reflex was established to a metronome beat of 120/min, and a negative conditional reflex to a metronome beat of 60/min. The foregoing experiments have described in brief the structural characteristics of the conditional reflex, together with the functional patterns, their dynamics and breakdown. It should be pointed out that this is an attempt to describe psychological functioning in its entirety through measurable behavioral manifestations.