Acquired drive strength as a joint function of UCS intensity and number of CS-UCS pairings: the effect of masses and distributed CS-UCS pairings.

The empirical law relating acquired drive strength, as measured by the latency of a hurdle-jump response, to UCS intensity and number of CS-UCS pairings was investigated. The effect on acquired drive strength of varying the intervals between successive CS-UCS pairings was also investigated. Ss were 150 male albino rats, 125-160 days old. The apparatus was the classically conditioned fear apparatus. Acquired drive strength was found to be curvillinearly related to UCS intensity and number of CS-UCS pairings when a 10 minute intertrial interval was used. The relationships were monotonic and hegatively accelerated. The effect of UCS intensity on acquired drive strength varied with the length of the intertrial interval. The findings of diverging functions relating UCS intensity to test trials support Spence's notion of multiplicative relationship between habit strength (sHr) and drive (d) in the determination of performance in aversive conditioning.