Intermittent punishment of Sdelta responding in matching to sample.

Incorrect matching responses of two pigeons on matching to sample were either continuously (CRF) or intermittently (FR) followed by a time out (TO). The matching accuracy was examined as a function of both TO duration and TO frequency (ratio size). With intermediate TO durations (10 sec, 1 min), accuracy increased as the frequency of TO increased. With an extremely short (1 sec) and an extremely long (10 min) TO duration, accuracy was poor over the entire range of frequencies.