Delayed reinforcement and delayed choice in symbolic matching to sample: Effects on stimulus discriminability.
Shrink the wait between prompt and response before you fuss about the wait between response and reward.
01Research in Context
What this study did
The team worked with pigeons in a symbolic matching-to-sample task.
They added two kinds of delays: one between the sample and the choice, and another between the choice and the food.
By moving each delay around, they could see which gap hurt the birds’ accuracy more.
What they found
Both gaps made the birds pick the wrong key more often.
The gap before the choice hurt far more than the gap after the choice.
In plain words, waiting to respond is worse than waiting for the treat.
How this fits with other research
Rider et al. (1984) saw the same drop when only the sample-choice gap grew, so the new split makes that old curve clearer.
Madden et al. (2003) later showed that longer reinforcer delays also steepen forgetting curves, backing up the smaller hit seen here.
Eisenmajer et al. (1998) seemed to flip the weight, claiming reinforcer delay matters most; their task used much longer food waits, so both studies fit once you see the ranges differ.
Why it matters
When you run conditional-discrimination programs, tighten the time between the prompt and the learner’s response first.
Letting a few extra seconds pass before delivering praise or tokens is far less harmful.
Next session, cut sample-response lag before you worry about speeding up your own reinforcer delivery.
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02At a glance
03Original abstract
Six pigeons were trained to peck a red side key when the brighter of two white lights (S(1)) had been presented on the center key, and to peck a green side key when the dimmer of two white lights (S(2)) had been presented on the center key. Equal frequencies of reinforcers were provided for the two types of correct choice. Incorrect choices, red side-key pecks following S(2) presentations and green side-key pecks following S(1) presentations, resulted in blackout. With 0-s delay between choice and reinforcement, the delay between sample presentation and choice was varied from 0 to 20 s. Then, with 0-s delay between sample presentation and choice, the delay between choice and reinforcement was varied from 0 to 20 s. Both types of delay resulted in decreased discriminability (defined in terms of a signal-detection analysis) of the center-key stimuli, but delayed choice had more effect on discriminability than did delayed reinforcement. These data are consistent with the view that the two kinds of delay operate differently. The effect of a sample-choice delay may result from a degradation of the conditional discriminative stimuli during the delay; the effect of a choice-reinforcer delay may result from a decrement in control by differential reinforcement.
Journal of the experimental analysis of behavior, 1986 · doi:10.1901/jeab.1986.46-293