d-Amphetamine-chlorpromazine antagonism in a food reinforced operant.

Scientists gave rats a fixed-ratio 10 food task. The rats had to press a bar ten times to earn a pellet.

After training, the rats got d-amphetamine. The drug stopped their bar pressing. Then the team gave chlorpromazine to see if it could reverse the stoppage.

Chlorpromazine brought the bar pressing back to normal. The drug pair acted like a light switch: amphetamine turned the behavior off, chlorpromazine turned it back on.

Baseline rates stayed the same, so the effect was a true reversal, not just sedation.

NEVIN et al. (1963) tested the same two drugs the same year. They used escape tasks instead of food tasks and saw the same push-pull pattern. Together the studies show the antagonism works across very different schedules.

Zigler et al. (1989) gave only chlorpromazine to pigeons in a memory task. Accuracy dropped, but the birds still pecked at normal speed. This extends the 1963 work by showing chlorpromazine can hurt memory without slowing movement.

Goldman et al. (1979) showed d-amphetamine wrecks new learning in monkeys while barely touching old habits. The 1963 paper adds that chlorpromazine can protect or rescue even well-trained behavior when amphetamine tries to shut it down.

If a client’s medication suddenly changes behavior, ask the medical team whether a counter-drug like chlorpromazine could be useful. Watch for schedule effects: the same antagonism seen in simple FR tasks can guide decisions during teaching or compliance programs where stimulant side effects appear.