Induced attack during fixed-ratio and matched-time schedules of food presentation.
Requiring responses on a fixed-ratio schedule fuels more aggression than giving the same amount of free food, so the work rule itself drives adjunctive attack.
01Research in Context
What this study did
The team worked with pigeons in a lab.
They compared two food schedules that gave the same number of treats per hour.
One schedule was a fixed-ratio: the bird had to peck a set number of times to earn each pellet.
The other schedule was variable-time: food just dropped in no matter what the bird did.
Both schedules kept the exact same feeding rate, so only the work rule changed.
What they found
Birds on the fixed-ratio schedule showed far more attack moves toward a nearby target.
The variable-time schedule produced little attack even though food arrived just as often.
The result shows it is not how often food comes, but whether the animal must work for it, that sparks extra aggression.
How this fits with other research
Zeiler (1968) first noticed that fixed-ratio schedules make pigeons aggressive.
That study left open whether the aggression came from the feeding rate or from the work rule.
Bhaumik et al. (2008) now answers the question: they held rate steady and still saw more attack on FR, proving the response requirement itself is the trigger.
Friedling et al. (1979) had shown that response-independent schedules (fixed-time) can also evoke attack.
The new study lines up beside it: when rate is matched, FR produces even higher attack than FT, tightening the picture of how schedule type controls adjunctive behavior.
Why it matters
If you use fixed-ratio programs with clients, watch for emotional spikes right after reinforcement.
The schedule itself, not just how often you deliver goodies, can create frustration.
Consider mixing in response-independent or variable-interval moments to dilute the response pressure and keep aggression low.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Add brief VT or free-access breaks after every few FR completions to bleed off schedule-induced tension.
02At a glance
03Original abstract
Adjunctive or induced behavior is generated during a variety of schedules of reinforcement. Several theoretical conceptualizations suggest that rate of reinforcement is the primary variable controlling the strength or levels of induced behavior. The operant response requirement within the schedule context has not been extensively studied as a determinant of induced responding. In the present study, levels of induced attack by food-deprived pigeons against restrained conspecifics were compared during response-dependent and response-independent schedules of food presentation equated or yoked interval-by-interval for reinforcement frequency. Experiment 1 compared levels of attack induced by fixed-ratio schedules of key pecking and yoked "matched-time" schedules. Experiment 2 similarly compared chained fixed-ratio 1 fixed-ratio 74 and yoked chained matched-time matched-time schedules. In both experiments, the response-dependent schedules generated greater levels (amount and probability) of induced attack than the response-independent time-based schedules. Thus, the ratio response requirement may be an important determinant of levels of induced responding, and the lower levels of attack observed during the response-independent condition may not be due to the absence of stimuli predicting food presentations. It is concluded that rate of reinforcement is not the sole variable determining levels of induced responding and that response-based and time-based schedules differ in their generation of induced responding.
Journal of the experimental analysis of behavior, 2008 · doi:10.1901/jeab.2008.89-31