Abstract
Duration of the post-reinforcement pause was measured for three pigeons on fixed-ratio schedules of reinforcement ranging from 10 to 160. Small sequential changes were made in the ratio values without disrupting stable performance. The post-reinforcement pause increased consistently for all birds within three sessions as the ratio requirement increased. A frequency analysis of the individual pauses at selected fixed ratios revealed an increase in dispersion for all animals as the ratio size increased. Response rate tended to decrease for two of the birds and remained relatively stable for the third; but there were many reversals in these data.