Effect of delay-interval stimuli on delayed symbolic matching to sample in the pigeon.
Visual filler during the wait window wrecks delayed discriminations, so strip the view to the bare task.
01Research in Context
What this study did
Pigeons pecked colored keys in a delayed matching-to-sample task. After the sample went off, a 0-6 second delay passed before the choice keys lit up.
During each delay the birds saw either darkness, a steady houselight, or white shapes on the wall. The team counted correct matches and total pecks.
What they found
Visual stimuli during the delay hurt accuracy. Birds scored fewer correct matches when the houselight or white shapes were on.
The same lights also cut the birds' key-peck rate in half. Auditory or tactile fill-ins did not harm performance.
How this fits with other research
Davis et al. (1994) seems to disagree. They showed that brief colored lights right after a correct choice sped learning, while Wilkie et al. (1981) found lights during the delay hurt accuracy. The difference is timing: lights tied to reinforcement help; lights that merely fill the interval distract.
Bernal et al. (1980) and Burgio et al. (1986) extend the story. E et al. proved that letting pigeons peck during the delay protects memory, matching the new finding that idle visual noise harms it. D et al. later showed that delaying either the choice or the reinforcer both lower accuracy, so extra visual clutter makes a bad situation worse.
Clark et al. (1970) set the stage. An orange flash that had been paired with food lured pigeons into wrong choices, foreshadowing that visual events can overpower stimulus control.
Why it matters
When you teach a child to pick the same picture after a pause, keep the table bare. Turn off the tablet, cover extra cards, and face the learner away from movement. One simple switch—cutting visual clutter during wait times—can save you from re-teaching a discrimination that delay noise just undid.
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02At a glance
03Original abstract
In Experiment 1, food-deprived pigeons received delayed symbolic matching to sample training in a darkened Skinner box. Trials began with the illumination of the grain feeder lamp (no food sample), or illumination of this lamp, accompanied by the raising of the feeder tray (food sample). After a delay of a few seconds, the two side response keys were illuminated, one with red and one with green light, with positions counterbalanced over trials. Pecking the red (green) comparison produced grain reinforcement if the trial had started with food (no food); pecking red after a no-food sample or green after a food sample was not reinforced. Once matching performance was stable, four stimuli were presented during the delay interval, and their effects on matching accuracy were evaluated. Both illumination of the houselight and the center key with white geometric forms decreased matching accuracy, whereas presentation of a tone and vibration of the test chamber did not. In Experiment 2, pecking the red center key was reinforced with food according to a variable interval schedule. The effects of occasional brief presentations of the four stimuli used in the first experiment on ongoing pecking were assessed. The houselight and form disturbed key pecking, but the tone and vibration did not. Thus, stimuli that interfered with delayed matching also interfered with simple operant behavior. Implications of these results for theories of remembering are discussed.
Journal of the experimental analysis of behavior, 1981 · doi:10.1901/jeab.1981.35-153