Extinction-induced aggression during errorless discrimination learning.
Errorless discrimination still ends in aggression when reinforcement stops — schedule thinning and package treatments are your safety net.
01Research in Context
What this study did
The team taught pigeons an errorless color discrimination. Birds got food every time they pecked the red key. They never got food for pecking the green key.
After the birds were perfect, the researchers stopped all food. They wanted to see if the birds would attack a nearby model bird when reinforcement ended.
What they found
Every pigeon started attacking the model as soon as food stopped. The attacks kept happening for 45 straight sessions.
Even though the birds had learned without errors, extinction still made them aggressive. The old food history in the red-key presence was enough to trigger attack when food vanished.
How this fits with other research
Morse et al. (1966) first showed that plain extinction makes pigeons aggressive. Jenkins et al. (1973) proves the same thing happens after fancy errorless training.
Kelly et al. (1970) found the same aggression spike in teenagers when money stopped. The pigeon data line up with human data — extinction can provoke attack across species.
Two years later Harrison et al. (1975) added a twist: birds on richer food schedules attacked even harder. The 1973 paper warned us that errorless does not mean harmless; the 1975 paper told us how to lower the risk — thin the schedule before you stop.
Why it matters
Errorless learning is great for clean acquisition, but the honeymoon ends when you withhold reinforcement. Plan for possible aggression, self-injury, or burst any time you fade reinforcers. Thin schedules first, embed extinction in a package, and monitor longer than you think you need to.
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02At a glance
03Original abstract
Pigeons were trained to discriminate without errors between a green light and a dark key. The key-pecking response was reinforced in the presence of green, and extinction was in effect in the presence of the dark key. The duration of the dark key was gradually increased during the first few sessions of conditioning. The opportunity to attack a restrained target pigeon was also present. During discrimination training, the rate of attack in the presence of the dark key was higher for each animal than the operant level, even though most of the animals acquired the discrimination without errors. Furthermore, the rate of attack did not decrease during 45 sessions of discrimination training. Attack also occurred in the presence of the green stimulus, although to a lesser extent than during extinction. Reinforcement during green is a determinant of attack during extinction because removal of reinforcement virtually eliminated attack during extinction.
Journal of the experimental analysis of behavior, 1973 · doi:10.1901/jeab.1973.20-85