A comparison of stimulus fading and stimulus shaping on perceptual category learning.

Errorless learning strategies such as stimulus fading and stimulus shaping are commonly used to teach complex skills like categorisation and concept formation. Despite widespread use, very few studies have explored the comparative effectiveness of these procedures in well-controlled analyses. The vast majority of existing studies have been undertaken with clinical populations and have involved small numbers of participants (e.g., Single-case designs). The present study sought to compare stimulus fading, stimulus shaping, and trial-and-error learning in a perceptual categorisation task. In Experiment 1, we found robust benefits of stimulus shaping when compared to stimulus fading or trial-and-error learning on measures of initial acquisition of discrimination and one measure of stimulus generalisation. These findings were replicated in a second experiment in which the dimension of fading/shaping was changed from a modification of the comparison stimuli (S-) to a modification of the target stimulus (S +). We discuss the implications of our findings for the selection of errorless learning strategies in clinical settings.