The development of stimulus control with and without a lighted key.
Extra lights or colors can block the cue you want the learner to notice.
01Research in Context
What this study did
Researchers worked with pigeons in a small lab chamber. Air blew from the left or right side. The birds had to peck a key when the airflow came from the correct side.
One group trained with the key lit. The other group trained in the dark. The team tracked how fast each group learned the airflow rule.
What they found
Birds that saw the glowing key took longer to notice the airflow cue. Their learning curve stayed flat.
Birds that pecked in the dark caught on faster. The lit key stole attention from the real signal.
How this fits with other research
Tracey et al. (1974) saw the same trouble. When a food-tray light flashed during key pecking, response rates dropped. Extra visual noise hurts performance even when it looks helpful.
Zentall et al. (1975) pushed the idea further. Brighter keylights cut autoshaped pecking in half. Together the three papers show a rule: the flashier the cue, the weaker the control.
Redd (1969) looks opposite at first. Those birds learned to peck under shock reduction alone, no food needed. But the key stayed dim. The dim key let the shock-light relation stay clear, matching today’s lesson: keep the target cue the star.
Why it matters
Your client rooms are full of “lit keys” — colorful posters, spinning toys, staff walking by. These extras can steal control from the cue you want to teach. Run a quick check: teach the skill once with decorations up, then with them gone. If responding sharpens in the plain room, you have found your overshadowing culprit. Strip the visuals and let the target stimulus shine.
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02At a glance
03Original abstract
In two experiments, the effect of an illuminated response key on the acquisition of stimulus control by an airflow stimulus was assessed. In the first experiment, pigeons were given nondifferential training with airflow emerging from behind the response key in one of three conditions of illumination: trained to peck a lighted key, trained to peck an unlighted key with a houselight present, trained to peck a key in total darkness. After 10 days of training on a variable-interval schedule of reinforcement, all subjects were given a generalization test on airflow velocity. The gradients for subjects trained in the dark were sharp, while those for subjects trained in lighted conditions were shallow. In the second experiment, the effect of an irrelevant keylight on the acquisition of an airflow velocity discrimination was assessed. Two groups of pigeons were trained to discriminate two airflow velocities. One group was trained with a lighted response key and the other was trained to peck the response key in total darkness. The dark-trained subjects acquired the discrimination more rapidly. The results demonstrate that the acquisition of stimulus control by airflow with either a differential or nondifferential training procedure can be overshadowed by keylight.
Journal of the experimental analysis of behavior, 1972 · doi:10.1901/jeab.1972.18-217