Resolving contradictory findings on sex and social class differences in children's responses to reinforcement

Contradictory results have been reported on the effectiveness of various reinforcers with children of different ages and socioeconomic classes. The present study considered the relative effectiveness of two types of verbal and one type of tangible reinforcement on a two-choice discrimination task (marble-in-the-hole) for preschool children. IQ and operant level were treated as covariates and accounted for the observed differences in performance between the 24 middle-class and 24 lower-class children and between the 24 males and 24 females. Disparate findings of previous studies regarding sex and social class differences might have been reconciled if baseline and IQ had been considered.