Assessment of attack and drinking in White King pigeons on response-independent food schedules.
Fixed-time food reliably sparks attack in pigeons, proving that schedule-induced aggression does not need a response requirement.
01Research in Context
What this study did
Researchers placed White King pigeons in small cages. Food arrived on a fixed-time schedule no matter what the birds did.
The team watched for two side effects: attack moves toward another bird and how much water each pigeon drank.
What they found
Every bird started attacking when food came on a timer. The strikes were quick and clear.
Drinking moved up for some birds and down for others. The food clock did not sway water intake the same way each time.
How this fits with other research
Dove et al. (1974) saw the same strikes under longer variable-interval schedules. Their birds hit hardest after each pellet, showing the timing of attack is tied to when food last arrived.
Bhaumik et al. (2008) pushed the idea further. They compared fixed-time food with fixed-ratio food that required pecks. Response-dependent schedules sparked even more attacks. The 1979 study now looks like the lower-bound case: attack still shows up when no work is needed, just less of it.
Duker et al. (1996) added that bigger food portions under fixed-interval schedules raise attack rate. Together the papers draw a simple curve: the longer or richer the timed food, the more likely adjunctive aggression becomes.
Why it matters
If you run edible reinforcement on a clock, watch for surges in problem behavior right after delivery. The pigeon data warn that fixed-time snacks can evoke aggression even when the learner does nothing to earn them. Consider spacing food thinner, adding response requirements, or teaching an incompatible movement to block the first strike.
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02At a glance
03Original abstract
Four White King pigeons in Experiment I were exposed to a fixed-time 90-second food schedule with successive access to water and a conspecific target. Drinking per session was sporadic and minimal, while attack per session occurred during most interfood intervals for all animals. Analysis of the temporal distribution of attack showed that the typical postreinforcement pattern of attack developed over the course of the experiment. In Experiment II, the same animals were exposed to a series of fixed-time schedules ranging from 30 to 360 seconds with successive access to water and target. Time engaged in drinking and the number of interfood intervals with drinking were less than that of attack. Food and no-food baselines, which have been typically used to assess schedules-induced drinking and attack, respectively, were used to evaluate the effect of the schedule on attack and water ingestion. Relative to the no-food baseline, both attack and drinking were enhanced by the schedule in all birds. Relative to the food baseline, drinking was slightly suppressed in three birds and attack was enhanced in all. For all animals, the food baseline resulted in more attack and drinking than the no-food baseline.
Journal of the experimental analysis of behavior, 1979 · doi:10.1901/jeab.1979.31-91