Cocaine's effects on food-reinforced pecking in pigeons depend on food-deprivation level.
Motivation level decides whether cocaine (and maybe other reinforcers) will speed or slow operant responding.
01Research in Context
What this study did
Scientists gave pigeons cocaine before a food-peck session.
They changed two things: how hungry each bird was and how much drug it got.
Birds pecked a key for grain while the team counted every response.
What they found
Low cocaine doses made hungry birds peck faster.
High doses slowed every bird down, but the drop was steeper when birds were less hungry.
Motivation level flipped the size and direction of the drug effect.
How this fits with other research
Gabriels et al. (2001) later showed that daily cocaine makes the same pigeons grow tolerant.
Together the two papers tell one story: first, hunger sets the starting curve; then, repeated exposure flattens it.
Frost et al. (1996) found bigger grain pellets also raise peck rate, proving reinforcer size and deprivation pull the same lever.
Kendall (1974) showed that pre-food stimuli can raise or lower rates depending on baseline speed, echoing how cocaine helps fast birds and hurts slow ones.
Why it matters
Your client’s motivation is like the pigeon’s hunger: it decides whether a new intervention will help or harm.
Before you add medication, token value, or schedule thinning, test responding at high and low motivation.
A quick probe session when the learner is satiated versus hungry can predict the drug, token, or schedule effect before you commit.
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02At a glance
03Original abstract
Four pigeons deprived to 80% of their laboratory free-feeding weights pecked keys under a multiple fixed-ratio 30 fixed-interval 5-min schedule of food presentation. Components alternated strictly with 15-s timeouts separating them; each was presented six times. When rates of pecking were stable, 2 pigeons' weights were reduced to 70%, and the other 2 pigeons' weights were increased to 82.5% to 85% of free-feeding levels. Cocaine (1.0, 3.0, 5.6, and 10.0 mg/kg and saline) was administered 5 min prior to sessions. When each dose had been tested twice, pigeons' weights were adjusted to the level that they had not yet experienced, and cocaine was tested again. Cocaine reduced response rates in a dose-dependent manner under the fixed-ratio schedule and under the fixed-interval schedule at high doses, and increased rates under the fixed-interval schedule at low low doses. Reductions in pecking rates occurred at lower doses under both schedules in 3 of 4 pigeons when they were less food deprived compared to when they were more food deprived. Low doses of cocaine increased low baseline rates of pecking in the initial portions of the fixed-interval schedules by a greater magnitude when pigeons were more food deprived. Thus, food-deprivation levels altered both the rate-decreasing and rate-increasing effects of cocaine. The implications of these results for the mechanisms by which food deprivation increases cocaine self-administration and for the dependence of cocaine's effects on the baseline strength of operant behavior are discussed.
Journal of the experimental analysis of behavior, 1995 · doi:10.1901/jeab.1995.64-61