Fixed-ratio schedule-induced aggression.
Fixed-ratio schedules can trigger aggression right after reinforcement, so monitor and buffer the post-payoff moment.
01Research in Context
What this study did
Pigeons worked on a fixed-ratio food schedule. After every set number of key pecks they got grain.
A second bird stood nearby. The team counted how often the working bird lunged or struck at the partner.
What they found
Attacks jumped right after grain delivery. The bigger the ratio, the more strikes the bird threw.
The pattern showed that FR schedules themselves can spark aggression.
How this fits with other research
Dardano (1970) ran the same setup and saw the same post-reinforcement spikes. The finding held across two labs.
Bhaumik et al. (2008) tightened the test. They kept food rate the same but removed the peck requirement. Strikes dropped, proving the response cost, not just food timing, drives the attack.
Waite et al. (1972) swapped FR for fixed-interval. Attacks still peaked after food, showing the effect crosses many periodic schedules.
Why it matters
If you run FR token boards, piece-rate work, or large response requirements, watch for sour mood, property destruction, or peer aggression right after the client earns the reinforcer. Build in quick breaks, smaller ratios, or choice to bleed off tension before it turns into problem behavior.
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02At a glance
03Original abstract
Pigeons' pecks were conditioned with food reinforcement. Subjects were exposed to sessions of no-reinforcement and of fixed-ratio reinforcement. The pigeons attacked a target animal during the fixed-ratio reinforcement conditions. The attack occurred primarily during the post-reinforcement pause and occurred after almost every instance of reinforcement. Little or no aggressive behavior was demonstrated during periods of no-reinforcement except on the initial days of these conditions. The results indicated that a fixed-ratio schedule of reinforcement has certain characteristics capable of producing aggression.
Journal of the experimental analysis of behavior, 1968 · doi:10.1901/jeab.1968.11-813