MATCHING BY EXCLUSION ON A BASELINE OF VISUAL CONDITIONAL DISCRIMINATIONS

Abstract

This study investigated responding by “exclusion”, a robust behavioural process demonstrated by the selection of an undefined comparison stimulus, when the sample is also an undefined stimulus, without any previous history that could establish the comparison as a discriminative stimulus for the selection response. “Exclusion” has been extensively replicated after the establishment of a baseline of auditory-visual discriminations. The purpose of this study was to investigate the emergence of exclusion using a baseline of visual-visual discriminations only. Two experiments used the same experimental arrangements used in previous studies, substituting the visual for the auditory stimuli, in which the baseline for the exclusion probes involved each sample related to many comparisons (Experiment I) and many samples related to each comparison (Experiment II). Nine children aged four to five years-old were exposed to the following experimental sequence: (a) establishment of a baseline of conditional discriminations with visual stimuli; (b) exclusion probes; (c) teaching new inter-related discriminations; (d) additional exclusion probes; and (e) probes of equivalence class formation. All children learned the conditional discriminations and showed positive results on exclusion probes and equivalence probes. These results extend previous findings on exclusion responding, demonstrating that it is not dependent on the auditory modality of the sample stimuli and the results strengthen the notion that this emergent behavior may derive from the same basic process involved in the formation of equivalence classes.Key-words: matching by exclusion, emergent behavior, conditional discrimination, stimulus control topography,selection, rejection