Emergent simple discrimination established by indirect relation to differential consequences

Three experiments examined a discrimination training sequence that led to emergent simple discrimination in human subjects. The experiments differed primarily in their subject populations. Normally capable adults served in the first experiment, preschool children in the second, and mentally retarded adults in the third. In all experiments, subjects learned a simple simultaneous discrimination: When visual stimuli Al and A2 were displayed together, reinforcers followed selections of Al, the S+, but not A2, the S-. The subjects also learned a conditional discrimination taught with an arbitrary visualvisual matching-to-sample procedure. Comparisons were two additional visual stimuli, BI and B2, and samples were Al and A2. Reinforcers followed selections of BI in the presence of Al and of B2 in the presence of A2. After the simple-discrimination and conditional-discrimination baselines had been acquired, Bl and B2 were displayed alone (without a sample) on probe trials. Subjects had never been taught explicitly how to respond to such displays. Nonetheless, they almost always selected Bl, which was involved in a conditional relation with Al, the stimulus that served as S+ on the simplediscrimination trials. This outcome suggested the formation of stimulus classes during conditionaldiscrimination training. Through class formation, Bl and B2 had apparently acquired stimulus functions similar to those shown by Al and A2 on simple-discrimination trials, thereby leading to emergent selections of Bl on the probes.