Autoshaped responding: A baseline for studying stimulus preference.
Brightness, not color, drives pigeons’ key peck in autoshaping.
01Research in Context
What this study did
Researchers used an autoshaping setup with pigeons. A colored key lit up before food arrived.
The team changed the brightness of each color. They watched which color the birds pecked most.
What they found
When brightness differed, pigeons picked the brighter key no matter the color.
After the team equalized brightness, the birds’ color choice flipped. Intensity ruled over hue.
How this fits with other research
Yuwiler et al. (1992) later darkened the key and saw the same thing—less light meant fewer pecks.
Jenkins et al. (1973) showed that food type shapes the form of the peck; Gillberg et al. (1983) add that stimulus intensity shapes which key is pecked.
Mulvaney et al. (1974) proved that mere stimulus-food pairing keeps the response alive; this paper shows intensity guides that response toward one key.
Why it matters
When you set up stimulus-stimulus pairing or SD training, brightness, volume, or size can outweigh the feature you thought the learner was “choosing.” Try matching intensity across options before you call one stimulus more preferred.
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02At a glance
03Original abstract
In an autoshaping procedure with pigeons, trials consisted of the illumination of two keys, each with a different color, and then a response-independent feeder operation. Over successive conditions, all key-color pairs were arranged from the set of amber, red, green, and blue lamps. During sessions with a given pair, the left-right configuration of the colors varied irregularly, and the two colors alternated in illuminating the feeder. With one red and one green key, for example, red appeared sometimes on the left and sometimes on the right, and the feeder was alternately lit red or green on successive trials. Both total pecks and proportion of trials with at least one peck on a key of a given color were generally greater for red and amber than for green and blue, and relations among preferences were generally transitive across different color pairs. Repeating the procedure with decreased red and amber intensities and increased green and blue intensities reduced red and amber pecking relative to green and blue pecking, implying that differences in responding were determined more strongly by intensive than by chromatic properties of the stimuli.
Journal of the experimental analysis of behavior, 1983 · doi:10.1901/jeab.1983.39-251