The stages of acquisition in stimulus fading.
Stimulus fading moves in two clear steps, so probe early to spot when control jumps from prompt to target.
01Research in Context
What this study did
Kodera et al. (1976) worked with pigeons to see how stimulus fading really happens.
The birds first pecked when dim red light plus a tilted line appeared together.
Then the red light was slowly removed so only the line would control pecking.
Researchers watched for two clear steps of control instead of one smooth slide.
What they found
Control moved in two jumps, not a steady fade.
First the birds listened to the red-plus-line combo.
Later they suddenly listened to the line alone.
If you blink you miss the pivot point, so probe early and often.
How this fits with other research
Wing (1981) later showed you can speed the same two steps by testing probes early.
That study used Braille with young adults and cut the number of fading levels needed.
Nevin (1967) also used gradual line tilts with monkeys and found fewer errors, but never showed the two-stage jump.
So the 1976 paper gives the basic map, and the 1981 paper gives a faster route.
Why it matters
When you fade prompts, do not assume the learner slides smoothly from prompt to target.
Insert quick probe trials right after each prompt reduction.
Watch for the moment the learner stops looking at the prompt and starts looking at the target cue.
Catch that pivot and you can drop the prompt faster with fewer errors.
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02At a glance
03Original abstract
Pigeons were exposed to a stimulus fading procedure in which control of responding was transferred from red and black stimuli to lines of different angular orientation. After superimposing one line on the red stimulus and the other line on the black stimulus, the intensity of the lines was gradually increased and that of the red stimulus was gradually reduced. Probes consisting of red and line stimuli presented separately were used during the course of fading to assess control exerted by each element of the compound. As the lines were faded in, they did not acquire control of responding. As red was faded out, control of responding was acquired first by the lower intensity red stimuli in combination with the line stimulus, and finally by the angular orientation of the lines. Probes also determined the point at which the line stimuli, presented alone, would maintain a high degree of stimulus control. The results demonstrated that new stimuli in fading acquire dimensional control of responding in two sequential stages. Acquisition of stimulus control in fading was explained in terms of attenuation of stimulus blocking.
Journal of the experimental analysis of behavior, 1976 · doi:10.1901/jeab.1976.26-295