On the minimal conditions for the development of a peak-shift and inhibitory stimulus control.

Failures to obtain a peak-shift and inhibitory stimulus control following massed extinction in the presence of intra- and interdimensional stimuli confirm earlier results reported by Honig, Thomas, and Guttman (1959) and by Weisman and Palmer (1969). Peak-shifts and inhibitory stimulus control were observed when any of the following procedures intervened for 3 min between massed extinction and generalization testing: (1) S+ presented, responding reinforced; (2) S+ presented, responding not reinforced; or, (3) noncontingent food presented in the presence of a dark key. Behavioral contrast was shown not to be a necessary antecedent for the occurrence of peak-shift or inhibitory stimulus control.