Acquired equivalence between stimuli trained in the same context.

The role of context was examined in human acquired equivalence. Participants were trained on two conditional discriminations. In the first conditional discrimination, if sample A1 was presented, choice of comparison B1, but not B2, was correct, and if sample A2 was presented, choice of comparison B2, but not B1, was correct. In the second conditional discrimination, if sample X1 was presented, choice of comparison Y1, but not Y2, was correct, and if sample X2 was presented, choice of comparison Y2, but not Y1, was correct. In each conditional discrimination, one of the conditional relations was trained in context 1 (e.g., A1 → B1 and X1 → Y1) and the other was trained in context 2 (i.e., A2 → B2 and X2 → Y2). On test trials, when conditional stimuli from the two conditional discriminations were interchanged (e.g., sample A1 was presented with comparisons Y1 and Y2) and were presented in a neutral context, positive transfer resulted. That is, in the absence of the training context, stimuli that shared a common context on different trials in training came to be treated as equivalent.