CLASSIFICATION OF VOWELS AND CONSONANTS BY INDIVIDUALS WITH MODERATE MENTAL-RETARDATION - DEVELOPMENT OF ARBITRARY RELATIONS VIA MATCH-TO-SAMPLE TRAINING WITH COMPOUND STIMULI

This study explored whether an identity-matching-based stimulus equiva lence procedure could be used to teach vowel and consonant stimulus cl asses to 2 adolescent females with moderate mental retardation. Delaye d march-to-sample trials presented a compound sample stimulus consisti ng of printed letters and a spoken word (''vowel'' or ''consonant''). The correct comparison stimulus matched only one of the letters in the compound sample. Subsequently, test trials assessed whether arbitrary relations had formed among the individual stimuli from each compound sample and whether stimuli from different compound samples had merged into larger stimulus classes. Both participants acquired five-member c lasses of vowel and consonant stimuli, which subsequently generalized to vocal classification and to identification in the context of four-l etter words. Follow-up tests showed that the generalized performances remained intact after 6 weeks. These procedures suggest an economical approach to stimulus class development.