Kenneth W. Spence

Cognitive factors in the extinction of the conditioned eyelid response in humans.

Rate of extinction of the conditioned eyelid response in humans is a function of the degree of discriminability of the procedural changes that occur with shift from acquisition to extinction. Extinction is greatly retarded when these changes are minimized or the subject is distracted by another task.

Intertrial reinforcement and the partial reinforcement effect as a function of number of training trials

An experiment involving rats in a runway, inter-trial reinforcement and three successive acquisition-extinction sequences substantiated and extended earlier findings that intertriai reinforcement diminished the partial reinforcement effect following a small number of acquisition trials, but not after extensive training.

Intrasubject Conditioning as a Function of the Intensity of the Unconditioned Stimulus

Subjects conditioned concurrently to two different conditioned stimuli, light and tone, exhibited a significantly higher level of conditioning to the stimulus paired with a strong unconditioned stimulus than to the stimulus paired with a weak one. The findings suggest that habit strength in aversive conditioning varies with the intensity of the unconditioned stimulus.

The effect of overlearning on rate of extinction of the eyelid CR

Human Ss were given either 50 or 150 eyelid conditioning trials in the context of a probability learning task. No difference was found in the subsequent extinction rate of the two groups. This finding contrasts sharply with the effects of similar overlearning on the rate of extinction of the instrumental runway responses. The results are interpreted as further evidence that the bases of inhibition are different in aversive and appetitionally motivated learning.

Conditioning (habit growth) in the absence of CRs

The assumption that conditioning (growth of H) developed in Ss who gave no eyelid CRs in an initial series of 10 reinforced trials was supported by data which showed that a subsequent test involving a difference in UCS intensity (level of D) led to a difference in level of response to the CS.

Individual differences in human eyelid conditioning

One-hundred Ss were conditioned successively to a tone and then a light. Conditioning performance was found to be highly consistent as shown by the correlation of.84 between the number of CRs given in 80 trials to each of the conditioned stimuli.