Date of Award


Degree Name

Master of Arts



First Advisor

Dr. Alan D. Poling

Second Advisor

Dr. Jack Michael

Third Advisor

Dr. Wayne Fuqua

Access Setting

Masters Thesis-Open Access


Four mentally retarded adults were taught to recognize (i.e., discriminate) finger spelling letters when presented as members of unchanging pairs (e.g., A and E, G and H). Correct responses were followed by food or verbal praise. On average, terminal accuracy was significantly greater when a correct response to a given letter was consistently followed by a particular outcome (e.g., food followed correct responses to A and praise followed correct responses to E) than when nondifferential outcomes were arranged (e.g., food followed 50% of all correct responses and praise followed the remaining 50%, regardless of whether the responses were to A or E). These findings suggest that the differential outcomes effect, which has been repeatedly demonstrated in nonhumans, can be established when teaching meaningful discriminations to mentally retarded people.