Conditioning of the aggressive behavior of pigeons by a fixed-interval schedule of reinforcement.
Aggression can be timed like any other operant when it is followed by reliable reinforcement.
01Research in Context
What this study did
Researchers placed hungry pigeons in small cages.
A feeder dropped grain every 60 seconds no matter what.
The birds could peck a target bird in the next cage.
Each attack was counted and timed.
What they found
The pigeons started attacking more right before food arrived.
Attack rate formed a scallop: low after food, high just before the next piece.
The timing of aggression matched the fixed-interval schedule.
Food reinforcement had conditioned when the birds fought.
How this fits with other research
Sachs et al. (1969) saw the same pattern in rats shocked with electricity.
Their fights dropped when the partner was drugged or passive.
Both studies show aggression is not just reflexive; it follows rules of reinforcement.
Winett et al. (1972) went further, proving past experience matters.
Rats that had learned to escape or win before fought harder later.
Together the papers say: reinforcement now and in the past shapes future aggression.
Why it matters
If you work with severe behavior, remember that aggressive bursts can be on a schedule.
Look for what comes right after the hit, bite, or kick.
If the payoff is steady, expect a fixed-interval scallop: calm early, rise late.
Change the timing of attention, escape, or items to flatten the scallop and reduce harm.
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02At a glance
03Original abstract
Operant reinforcement of aggression was studied in food-deprived pigeons by delivering food for attacks against a target pigeon. The food was delivered according to a fixed-interval schedule and attack behavior was recorded automatically. Attack could be conditioned and extinguished, and the proportion of time spent in attack was a direct function of the frequency of reinforcement of the attack. The fixed-interval schedule produced an increasing rate of attack during the interval between food reinforcements. This positive curvature was an inverse function of the duration of the interval. The findings revealed that the duration and temporal patterning of the complex social behavior of attack can be influenced in a substantial and predictable manner by the schedule and frequency of operant reinforcement.
Journal of the experimental analysis of behavior, 1967 · doi:10.1901/jeab.1967.10-395