Early and late introduction of probes and stimulus control acquisition in fading.
Probe early in your prompt fade to speed up accurate stimulus control.
01Research in Context
What this study did
Wing (1981) asked when to slip probe trials into a fading sequence.
Adults without disabilities learned Braille dot patterns.
Some people got probe trials early. Others got the same probes late.
What they found
Early probes cut the number of fading steps needed.
Learners reached accurate stimulus control faster.
Late probes made the road longer but still got there.
How this fits with other research
Kodera et al. (1976) first showed that stimulus control moves in two clear jumps, not a smooth slide. The 1981 study builds on that by proving you can catch the first jump sooner if you probe early.
Pritchard et al. (1987) also found that gradual beats trial-and-error, but they used rats and visual cues. The human Braille data line up: step-by-step with early checks beats waiting.
Belisle et al. (2021) brings the same probe logic into today’s clinics. They embed probes inside PEAK lessons to track progress without extra sessions, echoing the 1981 lab lesson: probe early, learn faster.
Why it matters
Next time you fade prompts, drop a probe trial right after the first prompt reduction. If the learner is right, you can skip the next baby step and move on. You save time and avoid prompt dependence.
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02At a glance
03Original abstract
College students learned to name Braille patterns presented visually using a fading procedure in which Braille patterns were superimposed on letter names after which letter names were attenuated. Measurement of acquisition was accomplished by presenting probes-consisting of the Braille stimuli only-throughout fading. Effects of probes upon acquisition were assessed by introducing probes early or late in fading. Fewer fading levels were needed for Braille elements to acquire control when probes were introduced early rather than late. When probes were introduced late, all subjects learned to name the Braille elements as the letters were being faded out. When probes were introduced early, however, most subjects learned to name the Braille elements as they were being faded in. Since virtually no errors occurred during compound-stimulus presentations, the probe procedure did not induce errors during acquisition. Quantitative analysis of probe data suggested that inclusion of probes enhanced the control acquired by the Braille elements during compound-stimulus presentations. The reported effects may have been due to differences in the relative frequency of reinforcement presented during compounds and probes.
Journal of the experimental analysis of behavior, 1981 · doi:10.1901/jeab.1981.36-363