Abstract
A mechanism for the disinhibition of displacement activities is proposed, by which a factor arising from non-reward causes attention to be switched to irrelevant aspects of the stimulus situation. In addition to evidence already extant, three lines of evidence are presented for the case of displacement pecking in the Barbary dove: (1) partially rewarded doves learn more about incidental aspects of a discrimination situation than consistently rewarded doves; (2) partially rewarded doves respond more readily to irrelevant stimuli than consistently rewarded doves; (3) doves which take longest to extinguish a simple approach response, also spend most time displacement pecking.