Changeover delay effects on topographically tagged discriminative behavior.

In a multiple variable-interval extinction schedule, pigeons' responses on an operant key were differentially reinforced in the presence of discriminative stimuli located on a signal key. Changeover delays of zero, one, two, or four seconds specified the time following a signal-key response within which an operant-key response was not reinforced. Systematic reduction of signal-key response rates with increasing changeover-delay duration indicated that signal-key responding was largely maintained by reinforcement of adventitious signal-key/operant-key response chains.