Selective antagonism of the rate-decreasing effect of d-amphetamine by chlorpromazine in a repeated-acquisition task.
Chlorpromazine can undo d-amphetamine’s slowness but not its accuracy problems.
01Research in Context
What this study did
The team gave pigeons a repeated-acquisition task. Birds had to learn a new four-peck sequence each session.
On some days they got d-amphetamine. On others they got both d-amphetamine and chlorpromazine. The researchers tracked how fast the birds pecked and how many errors they made.
What they found
Chlorpromazine brought the peck rate back up when d-amphetamine had slowed it. But errors did not fall. In fact, wrong sequences rose.
So the same drug pair had opposite effects: speed improved, accuracy worsened.
How this fits with other research
COLWINOGRAD (1965) saw much the same in pigeons on a fixed-ratio schedule. Chlorpromazine restored the low response rate caused by d-amphetamine. The new study shows the benefit disappears when you also count errors, not just speed.
Valentine et al. (1981) swapped chlorpromazine for chlordiazepoxide. They found punished responding rose with the new drug while d-amphetamine still cut it. Together the papers warn that one drug can reverse another on one measure yet leave or add harm on a second.
No true contradiction exists: earlier work only watched response rate. The 1980 paper widens the lens to accuracy, revealing a trade-off.
Why it matters
If you ever interpret drug effects on client behavior, look at more than one measure. A child might press a switch faster but make more mistakes after a medication change. Collect both speed and accuracy data before you judge a drug interaction as helpful or harmful.
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02At a glance
03Original abstract
Pigeons acquired a different four-response chain each session by responding sequentially on three keys in the presence of four colors. The response chain was maintained by food presentation under a fixed-ratio schedule. When d-amphetamine was administered alone, the overall response rate decreased and the percent errors increased with increasing doses. When a small dose of chlorpromazine, which was ineffective when given alone, was administered in combination with d-amphetamine, the rate-decreasing effect was antagonized. The antagonism was selective, however, in that the error-increasing effect of d-amphetamine was augmented by chlorpromazine. The nature of the joint effect of the two drugs thus depended on the behavioral measure: rate vs. accuracy.
Journal of the experimental analysis of behavior, 1980 · doi:10.1901/jeab.1980.34-87