Choice and conditioned reinforcement.
Conditioned reinforcers only boost preference when the final rewards are unequal and the signal comes right after the response.
01Research in Context
What this study did
Researchers let pigeons pick between two keys. Each key led to a different chain of lights.
The chains ended with the same amount of food or different amounts. The team counted how many times the birds chose each side.
They wanted to know if the rate of blinking lights alone could steer choice when the final food stayed equal or became unequal.
What they found
When both chains ended with the same food, the birds split their choices evenly. Extra blinking lights did not tip the scale.
When one chain ended with more food, the birds favored that side. More blinking lights on the rich side made the favoritism stronger.
The results lined up with delay-reduction theory: lights only matter when the payoff difference is already there.
How this fits with other research
Varley et al. (1980) first showed that a simple light change can act like a reinforcer. Dykens et al. (1991) now add that the rate of that light matters only after payoff inequality is set.
Davis et al. (1994) found that timing beats sheer rate: lights help learning only if they follow the response right away. Together the two papers warn that immediacy and payoff difference, not just more signals, drive choice.
Shimp et al. (1974) proved pigeons track overall payoff ratios. The new study keeps those ratios constant and shows that conditioned reinforcers ride on the same ratio wave rather than create a new one.
Why it matters
For BCBAs this means extra praise or tokens will not shift behavior if the natural payoff is already balanced. First make sure the better outcome truly gives more value, then add your conditioned reinforcers. Check that praise lands right after the target act; delay will water it down.
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02At a glance
03Original abstract
A potential weakness of one formulation of delay-reduction theory is its failure to include a term for rate of conditioned reinforcement, that is, the rate at which the terminal-link stimuli occur in concurrent-chains schedules. The present studies assessed whether or not rate of conditioned reinforcement has an independent effect upon choice. Pigeons responded on either modified concurrent-chains schedules or on comparable concurrent-tandem schedules. The initial link was shortened on only one of two concurrent-chains schedules and on only one of two corresponding concurrent-tandem schedules. This manipulation increased rate of conditioned reinforcement sharply in the chain but not in the tandem schedule. According to a formulation of delay-reduction theory, when the outcomes chosen (the terminal links) are equal, as in Experiment 1, choice should depend only on rate of primary reinforcement; thus, choice should be equivalent for the tandem and chain schedules despite a large difference in rate of conditioned reinforcement. When the outcomes chosen are unequal, however, as in Experiment 2, choice should depend upon both rate of primary reinforcement and relative signaled delay reduction; thus, larger preferences should occur in the chain than in the tandem schedules. These predictions were confirmed, suggesting that increasing the rate of conditioned reinforcement on concurrent-chains schedules may have no independent effect on choice.
Journal of the experimental analysis of behavior, 1991 · doi:10.1901/jeab.1991.55-177