Magnitude and duration of the effects of cocaine on conditioned and adjunctive behaviors in the chimpanzee.
Cocaine only speeds responding when the schedule is time-based; ratio or adjunctive behaviors stay flat or drop.
01Research in Context
What this study did
Scientists gave cocaine to a chimp that was already pressing a button for food.
They watched how the drug changed three things: button pressing on a fixed-interval schedule, button pressing on a fixed-ratio schedule, and extra drinking that happens between food deliveries.
They tried different doses to see which behaviors moved and which stayed the same.
What they found
Small and medium cocaine doses made the chimp press faster only during the fixed-interval part.
The same doses did nothing to fixed-ratio pressing or to the extra drinking.
A high dose shut everything down and even caused seizures.
How this fits with other research
Pierce et al. (1994) later saw the same drug speed up baboon reaction times, showing the schedule, not the species, decides the change.
Davison et al. (1995) found big rate increases when rats worked for timeout from shock, proving cocaine can raise output when the contingency is right.
Yoon et al. (2009) built on this work by showing pigeons grow tolerant to cocaine’s rate drops, meaning the schedule-specific effect can wear off with repeated use.
Together the four papers say: cocaine never helps every behavior at once; it only boosts the ones tied to time-based schedules or special reinforcers.
Why it matters
If you ever consult on cases where clients take stimulant medication, remember the contingency matters as much as the drug. A fixed-interval homework schedule might show faster work, while a fixed-ratio chore chart could look unchanged. Match your data paths to the schedule, not just the dose.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Plot each client’s response rate by schedule type before and after any stimulant change to see if only interval tasks move.
02At a glance
03Original abstract
Characteristic patterns of conditioned key-pressing were maintained in the chimpanzee under a multiple 30-response fixed-ratio, 10-minute fixed-interval schedule of food presentation. Adjunctive drinking occurred with regularity during the fixed-interval schedule and, with less frequency, during 1-minute timeout periods that followed each food presentation; drinking seldom occurred during the fixed-ratio schedule. Cocaine increased key pressing under the fixed-interval schedule at doses between .1 and 3.0 mg/kg, but adjunctive drinking and key pressing under the fixed-ratio schedule did not increase at any dose. Conditioned and adjunctive behaviors were disrupted and suppressed for different durations at 10,0 mg/kg, a dose which induced convulsive seizures within 10 minutes after intramuscular injection. A time-course analysis showed the magnitude and duration of the effects of cocaine on key pressing under the fixed-interval schedule and on adjunctive drinking to be dose-related. Moreover, a given dose of cocaine had diverse effects, depending on the behavior and the time since drug administration.
Journal of the experimental analysis of behavior, 1980 · doi:10.1901/jeab.1980.33-131