Behavioral contrast in chained schedules.
Behavioral contrast in chains means a lean first step can raise responding in the next, richer step.
01Research in Context
What this study did
Hineline et al. (1969) looked at chained schedules with pigeons. The birds pecked in two links. Link one never gave food. Link two gave food on a variable-interval schedule.
They compared response rates when the two links ran together versus when link two ran alone.
What they found
Response rates in the food link were higher when it was part of the chain. The same link, alone, produced lower rates.
This jump is called behavioral contrast. The poorer first link made the second link more valuable.
How this fits with other research
Romanowich et al. (2013) extend this idea to drugs. They showed that chlordiazepoxide changes response rates only when the middle link context shifts, echoing the contrast effect.
Zimmerman (1969) used conditioned reinforcers instead of food. His mixed results show that contrast can shrink if the earlier link uses weaker stimuli.
Neuringer (1973) found higher rates when responses truly produced reinforcers. Together these papers show that both stimulus and dependency matter for contrast.
Why it matters
You can use contrast to boost motivation. Put a lean schedule or non-reinforced task right before the target task. The learner will work faster in the rich component. Watch for contrast collapse if earlier stimuli are too weak or if drugs alter arousal. Test contrast during assessments to see if schedule changes help your client.
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02At a glance
03Original abstract
In each of two experiments, the rate of key pecking maintained by a variable-interval food reinforcement schedule was measured, first when that schedule was studied in isolation, and then when it was correlated with the second component of a two-component chained schedule. In the first experiment, the first component of the chained schedule was correlated with a fixed-interval schedule; in the second experiment it was correlated with a variable-interval schedule. In both experiments, behavioral contrast was demonstrated in the second component of the chained schedule. Compared to the rate of responding on the food-reinforcement schedule when it had operated in isolation, the rate of responding on the food-reinforcement schedule when it was correlated with the second component was higher, while the rate on the schedule of the first component was lower. The results are discussed with reference to the determinants of contrast.
Journal of the experimental analysis of behavior, 1969 · doi:10.1901/jeab.1969.12-905