The “disinhibition” of extinguished operant behavior in pigeons: Trial-tempo shifts and novel stimulus effects

After conditioning and extinction of keypecking with 25-see intertrial intervals between key illuminations, an immediate change to 5-sec intertrial intervals reinstated pecking during trials. Brief illuminations of the chamber during intertrial intervals also temporarily restored extinguished keypecking. The same manipulations of trial tempo and chamber illumination usually weakened well established, still reinforced keypecking. No recovery of extinguished behavior occurred when the intertrial interval was shifted upward from 5 sec to 25 sec. These and other behavioral findings were examined in relation to (a) Pavlov’s and Skinner’s research and views on “disinhibition” and “external inhibition” and to (b) analogous phenomena in physiological studies of habituation and dishabituation. The reliable evidence of disinhibition obtained in the present experiments suggests the involvement of an inhibitory process in extinction.