Aggression as positive reinforcement in mice under various ratio- and time-based reinforcement schedules.
Aggression can be a reinforcer that obeys the same schedule rules as food, water, or cocaine.
01Research in Context
What this study did
Researchers let mice earn short fights by poking their nose into a hole.
They used four classic schedules: fixed ratio, fixed interval, progressive ratio, and differential reinforcement of low rates.
The team wanted to know if fighting would keep the nose-poke going like food or water does.
What they found
Aggression worked just like standard reinforcers.
Mice produced the same scallops, pauses, and break-points that textbooks show for food.
The pattern proved the fight itself was the payoff, not just a side effect.
How this fits with other research
Kirby et al. (1981) showed that food schedules can trigger extra attacks in pigeons. E et al. flip the picture: here the fight is the reward, not the after-shock.
Gardner et al. (1976) found that cocaine injections drive typical FR and FI patterns in monkeys. E et al. match those shapes using brawls instead of drugs, stretching schedule law to a new reinforcer class.
BURNSTEIN et al. (1964) got the same FR slowdown and pause lengthening when wheel-running paid for licks. Aggression follows the same rules, so the mechanism is the schedule, not the snack.
Why it matters
If an aggressive outburst can reinforce the response that produces it, then behavior plans must guard against accidentally strengthening the very acts we want to reduce. Check your contingencies: a child might work hard to reach the moment he can hit. Build alternate, safer reinforcers that meet the same function before the blow lands.
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02At a glance
03Original abstract
There is evidence suggesting aggression may be a positive reinforcer in many species. However, only a few studies have examined the characteristics of aggression as a positive reinforcer in mice. Four types of reinforcement schedules were examined in the current experiment using male Swiss CFW albino mice in a resident-intruder model of aggression as a positive reinforcer. A nose poke response on an operant conditioning panel was reinforced under fixed-ratio (FR 8), fixed-interval (FI 5-min), progressive ratio (PR 2), or differential reinforcement of low rate behavior reinforcement schedules (DRL 40-s and DRL 80-s). In the FR conditions, nose pokes were maintained by aggression and extinguished when the aggression contingency was removed. There were long postreinforcement pauses followed by bursts of responses with short interresponse times (IRTs). In the FI conditions, nose pokes were maintained by aggression, occurred more frequently as the interval elapsed, and extinguished when the contingency was removed. In the PR conditions, nose pokes were maintained by aggression, postreinforcement pauses increased as the ratio requirement increased, and responding was extinguished when the aggression contingency was removed. In the DRL conditions, the nose poke rate decreased, while the proportional distributions of IRTs and postreinforcement pauses shifted toward longer durations as the DRL interval increased. However, most responses occurred before the minimum IRT interval elapsed, suggesting weak temporal control of behavior. Overall, the findings suggest aggression can be a positive reinforcer for nose poke responses in mice on ratio- and time-based reinforcement schedules.
Journal of the experimental analysis of behavior, 2009 · doi:10.1901/jeab.2009.91-185