Stimulus effects on local preference: stimulus-response contingencies, stimulus-food pairing, and stimulus-food correlation.
Stimuli boost performance when they are both response-contingent and predictive of where reinforcement will land.
01Research in Context
What this study did
Michael and team worked with pigeons on two-key concurrent schedules.
Birds earned grain on variable-interval timers.
The researchers added colored lights that either followed a peck or showed up for free.
They asked: does pairing the light with food make it a reinforcer, or does the light need to signal where the next grain will drop?
What they found
When the light came only after a peck and matched the next grain side, pigeons quickly shifted their key preference.
Lights that were merely paired with food, but gave no clue about grain location, did nothing.
The birds cared about information, not history with food.
How this fits with other research
Clark et al. (1970) looked like they disagreed. Their orange flash, once paired with grain, wrecked matching accuracy.
The clash clears up when you see timing: B’s flash arrived after wrong pecks, so it acted like a reinforcer for errors.
Michael’s flash arrived before grain and told the bird where to go next; it worked as a signal, not a treat.
Davis et al. (1994) back this up: stimuli help only when they follow the response right away and point to what pays off next.
Why it matters
For your clients, make tokens, praise, or lights happen right after the target response and make them say “the good stuff is over here.” Skip mere pairing sessions where the stimulus just hangs out with reinforcement but gives no directions. You will sharpen choice and speed up learning.
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Join Free →Arrange tokens so the client earns one immediately after the correct response and each token color tells where the next reinforcer will be delivered.
02At a glance
03Original abstract
Four pigeons were trained in a procedure in which concurrent-schedule food ratios changed unpredictably across seven unsignaled components after 10 food deliveries. Additional green-key stimulus presentations also occurred on the two alternatives, sometimes in the same ratio as the component food ratio, and sometimes in the inverse ratio. In eight experimental conditions, we varied the contingencies surrounding these additional stimuli: In two conditions, stimulus onset and offset were noncontingent; in another two, stimulus onset was noncontingent, and offset was response contingent. In four conditions, both stimulus onset and offset were contingent, and in two of these conditions the stimulus was simultaneously paired with food delivery. Sensitivity to component food ratios was significantly higher when stimulus onset was response contingent compared to when it was noncontingent. Choice changes following food delivery were similar in all eight conditions. Choice changes following stimuli were smaller than those following food, and directionally were completely determined by the food-ratio:stimulus-ratio correlation, not by the stimulus contingency nor by whether the stimulus was paired with food or not. These results support the idea that conditional reinforcers may best be viewed as signals for next-food location rather than as stimuli that have acquired hedonic value, at least when the signals are differential with respect to future conditions.
Journal of the experimental analysis of behavior, 2010 · doi:10.1901/jeab.2010.93-45