Comparison of timing and classical conditioning.

Four experiments with 63 Charles River and Sprague-Dawley rats investigated whether the timing of a stimulus (sound) correlated with the strength of a CR to the stimulus. The timing (effective duration) of the stimulus was measured with the peak procedure, similar to a discrete-trials, fixed-interval procedure. Ss were trained so that their response rate reached a maximum at approximately 40–60 sec after the onset of a light; the time of the maximum measured from the start of the light (peak time) was the measure of timing. On some trials, the light was preceded by a short (5-sec) or long (20- or 30-sec) interval of sound. It was assumed that the difference in peak time after long and short sounds reflected the timing of the sound: If the sound was timed, the longer sound would produce a lower peak time; if the sound was not timed, the 2 durations of sound would produce the same peak time. The CR was leverpressing during the sound. The sound was treated in various ways: presented alone (Exps I, III, and IV), followed by food (Exps I, III, and IV), preceded by food (Exp III), and followed by food after 20-sec (Exp IV). Treatments that produced no timing of sound produced no CR, and treatments that increased (or decreased) timing also increased (or decreased) the CR. Findings suggest that there is overlap between the mechanisms that produce time discrimination and the mechanisms that produce classical conditioning. (41 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)