Attack produced by intermittent reinforcement of a concurrent operant response.

Scientists watched monkeys work for food on a fixed-ratio schedule. Each monkey had to press a lever several times to get a bite.

When the food stopped, the team gave the animal a chance to bite a rubber tube. They counted how often the monkey attacked the tube.

Biting jumped as soon as the food ended. Biting also rose when the ratio got bigger before the stop.

The result shows that simply withholding reinforcement can spark aggression, even in primates.

Morse et al. (1966) saw the same pattern two years earlier, but in pigeons. The bird study proves the effect is not special to monkeys.

Hatton et al. (1999) later moved the idea into clinics. About half of kids with self-injury showed bursts or aggression when staff used extinction alone.

Capio et al. (2013) seems to disagree at first. They found that intermittent reinforcement made behavior easier to extinguish. The key difference is the measure: M looked at how long the old response lasted, while R looked at new aggression that popped out. Both papers warn that reinforcement history shapes what happens when you stop delivering reinforcers.

Before you place a behavior on extinction, plan for the burst. Tell staff and parents that hitting, screaming, or even biting may rise at first. Pair extinction with other tools such as differential reinforcement or antecedent strategies to cushion the spike. Document the burst so everyone knows it is expected, not a sign of failure.