Effects of cocaine on simple reaction times and sensory thresholds in baboons.
Cocaine speeds simple reactions only at low doses, showing the same inverted-U curve seen in reinforcement studies but the opposite of complex-learning studies.
01Research in Context
What this study did
Scientists gave baboons daily shots of cocaine. They then tested how fast each animal could press a button when a light came on.
The team also checked if the drug changed how bright the light had to be before the baboon noticed it.
What they found
Low cocaine doses made the animals react 10–12 % faster. Higher doses did not help and sometimes slowed them down.
The drug did not change how bright the light needed to be. Only speed, not seeing, was affected.
How this fits with other research
Goldman et al. (1979) saw the opposite: cocaine hurt pigeons’ learning and made more errors. The tasks differed—simple speed vs. hard discrimination—so the drug helps easy work but harms hard work.
Northup et al. (1991) showed an inverted-U with cocaine as a reinforcer: low doses increased lever presses, high doses dropped them. The same curve appears here—low dose speeds reaction time, high dose does not.
Elsmore et al. (1994) gave cocaine while animals worked for food and for avoiding timeout. Cocaine slowed both behaviors. Again, the task matters: simple reaction time is helped, while complex food and avoidance work is hurt.
Why it matters
The lesson for BCBAs is that drug or environmental effects can flip with task difficulty. When you see sudden gains in easy skills but drops in hard ones, check if the same variable—medication, sleep, or reinforcement rate—might be in play. Use easy probes to spot early drug effects and hard probes to catch side effects.
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02At a glance
03Original abstract
The effects of chronic, daily administration of cocaine on auditory and visual reaction times and thresholds were studied in baboons. Single intramuscular injections of cocaine hydrochloride (0.1 to 5.6 mg/kg) were given once daily for periods of 10 to 25 days, and were followed immediately by psychophysical tests designed to assess cocaine's effects on simple reaction times as on auditory and visual threshold functions. Consistent reductions in reaction times were frequently observed over the cocaine dose range of 0.32 to 1.0 mg/kg; at higher doses, either decreases or increases in reaction times were observed, depending upon the animal. Lowered reaction times generally occurred immediately following the 1st day's cocaine injection, and continued through all subsequent days during the dose administration period, suggesting little development of tolerance or sensitivity to these reaction-time effects. Reaction-time decreases showed a U-shaped dose-effect function. The greatest decreases in reaction times occurred from 0.32 to 1.0 mg/kg, and produced an average reaction-time decrease of 10 to 12%. Concurrently measured auditory and visual thresholds showed no systematic changes as a function of cocaine dose. Pausing was observed during performance of the psychophysical tasks, with the length of total session pause times being directly related to cocaine dose.
Journal of the experimental analysis of behavior, 1994 · doi:10.1901/jeab.1994.61-231