Control of pigeons' pecking by trace stimuli.
A short gap between cue and response can dull fine stimulus control even when the overall rule is still followed.
01Research in Context
What this study did
Researchers taught pigeons to peck only when a line tilted a certain way.
The line stayed on for a moment, vanished, then the birds chose.
This gap between cue and choice is called a trace interval.
What they found
The birds learned the broad rule: peck after the line.
Fine control by exact tilt faded when the gap grew.
Extra training helped, but the control stayed weaker.
How this fits with other research
Wilkie (1973) showed pigeons notice both color and tilt only when both pay.
The 1977 trace study adds time: even if both pay, a gap can still blur tilt control.
Bernal et al. (1980) later found longer gaps hurt accuracy more, matching the tilt fade seen here.
Kunz et al. (1982) then showed relational cues start weaker and decay the same rate, explaining why tilt—already subtle—suffered first.
Why it matters
When you teach a child to wait then respond, remember the cue can lose sharpness.
If the skill needs exact detail, keep the gap short or add extra practice after the wait.
Use broader cues for waits you cannot shorten.
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After a delay task, probe the exact feature you want (color, shape, tilt) to be sure it still controls responding—retrain if accuracy drops.
02At a glance
03Original abstract
In Experiment I, pigeons' pecking a white key was reinforced with grain when white was immediately preceded by a vertical white line on a green surround, but not by green alone. This procedure produced control of pecking by the line. Next, pecking white was reinforced after vertical line on green, but not after green alone or other orientations of the white line on green. The line-tilt dimension initially did not control pecking, a result that showed that interdimensional (line versus no line) training does not always result in dimensional control. Line-tilt control was eventually established but was accompanied by a decrease in interdimensional control. In Experiment II, interdimensional training, with or without a trace interval intervening between line on green or green alone and white, was followed by tests for line-tilt control. While interdimensional control was unaffected by the trace interval, line-tilt control tended to be less with the trace interval. This dissociation of interdimensional and dimensional control, as well as the failure of interdimensional training to produce dimensional control in Experiment I, suggests that the line stimulus is multidimensional.
Journal of the experimental analysis of behavior, 1977 · doi:10.1901/jeab.1977.27-293