Fig. 1. Rates of responding (responses/s) during baseline (BL) and 1-, 2-, or 3-days off from access to food (open bars) or cocaine (filled bars).

Baseline responding was the mean from sessions preceding all “days off” sessions. Data shown are means ± SEM for control monkeys (N = 5) and cocaine self-administration monkeys (N = 8). Asterisk indicates signficant differences between baseline food- and cocaine-group response rates; section sign indicates significant differences in response rates between baseline and extinction session responding.