Context effects on choice.
Local cues next to the response drive choice more than the overall payoff rate.
01Research in Context
What this study did
Alvarez et al. (1998) watched pigeons choose between two keys in a chain schedule.
Each key led to a final link where food could appear.
The team changed the local lights and the overall rate of food to see which one guided choice.
What they found
The birds always followed the nearby light cues, not the overall rate of food.
Even when the math said the other key paid better, the local signal won.
Four tests gave the same result: context beats calculation.
How this fits with other research
Iwata (1993) showed pigeons can track overall rate when both keys are present.
The new study seems to disagree, but the setups differ. A let birds see both keys at once; N used chained links where only one key shows at a time.
Dougherty et al. (1996) also used chained links and found delay, not ratio, rules choice. N adds that local lights, not delays, can be the cue that matters.
Boutros et al. (2009) later showed that even in a steady room, paired lights still tweak local pecks. This keeps the local-over-global theme alive.
Why it matters
When you set up token boards, DRH, or VR schedules, the nearest signal wins.
Put clear, consistent cues right next to the response you want.
Don’t trust the learner to do the math across time; give them a local sign.
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02At a glance
03Original abstract
Four pigeons responded on a concurrent-chains schedule in four experiments that examined whether the effectiveness of a stimulus as a conditioned reinforcer is best described by a global approach, as measured by the average interreinforcement interval, or by a local contextual approach, as measured by the onset of the stimulus preceding the conditioned reinforcer. The interreinforcement interval was manipulated by the inclusion of an intertrial interval, which increased the overall time to reinforcement but did not change the local contingencies on a given trial A global analysis predicted choice for the richer alternative to decrease with the inclusion of an intertrial interval, whereas a local analysis predicted no change in preference. Experiment 1 examined sensitivity to intertrial intervals when each was signaled by the same houselight that operated throughout the session. In Experiment 2, the intertrial interval always was signaled by the stimulus correlated with the richer terminal link. In Experiment 3, the intertrial interval was signaled by the keylights correlated with the initial links and two novel houselights. Experiment 4 provided free food pseudorandomly during the intertrial interval. In all experiments, subjects' preferences were consistent with a local analysis of choice in concurrent chains. These results are discussed in terms of delay-reduction theory, which traditionally has failed to distinguish global and local contexts.
Journal of the experimental analysis of behavior, 1998 · doi:10.1901/jeab.1998.70-301