The role of intermittent food in the induction of attack in pigeons.
Even steady, unpredictable food can spark aggression, so watch for post-reinforcement attack on rich schedules.
01Research in Context
What this study did
Researchers watched pigeons on variable-interval food schedules. They wanted to know if steady, unpredictable food alone could trigger attack behavior.
Birds lived alone in cages. A feeder dropped grain every so often. The team counted pecks at other pigeons shown on video.
What they found
Even without food cues, pigeons still attacked after grain delivery. The attack was weaker than when cues signaled the food.
Steady intermittent food can spark aggression. Schedules with clear signals stay stronger at bringing out attack.
How this fits with other research
Lancioni et al. (2009) push the idea further. In mice, biting actually worked like food or water to keep nose pokes going. The pigeon study shows attack as a side effect; the mouse study shows attack as fuel.
Bromley et al. (1998) looked at short gaps between food. They found those gaps cut the pause after grain. Kirby et al. (1981) found gaps can also bring out attack. Both tell us food timing shapes what happens next.
Older pigeon work by Solnick et al. (1977) and Dove (1976) set the stage. They showed how food rate and component length shift responding. The 1981 paper adds a new twist: food schedule alone can spark aggression.
Why it matters
If you run rich schedules with clients, watch for surprise aggression. A child on dense VR or VI for tantrum reduction might start hitting right after tokens or snacks. Check for this pattern during your next session. If it shows up, thin the schedule or add signals so the learner can predict when reinforcement is coming.
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02At a glance
03Original abstract
The present experiments evaluated whether transitions in reinforcer probability are necessary to induce attack in pigeons. In Experiment I, three of six pigeons exposed to response-contingent constant-probability food schedules and a photograph of a conspecific as a target exhibited sustained postreinforcement attack on the target. The postreinforcement pattern of attack developed over the course of the experiment and was accompanied by a reduction in the rate of postreinforcement key pecking and an increase in the postreinforcement pause in key pecking. These effects on key pecking resulted in unprogrammed variations in the probability of reinforcement which may have been responsible for the induction of attack. In Experiment II, the attack-inducing properties of a constant-probability response-independent food schedule were compared to a periodic food schedule matched for overall rate of food delivery and to a no-food condition. In addition to attack, the spatial location of the subjects was monitored during each interfood interval. The periodic and aperiodic food schedules generated very different patterns of spatial location. Postfood attack was induced by both food schedules, although the constant-probability schedule induced attack in fewer birds. The no-food condition was not effective in inducing attack in any birds. These experiments indicate that intermittent food schedules without reductions in reinforcer probability are sufficient to induce attack in some pigeons, although not as effective as schedules with transitions in reinforcer probability.
Journal of the experimental analysis of behavior, 1981 · doi:10.1901/jeab.1981.36-101