REVERSAL OF BASE-LINE RELATIONS AND STIMULUS EQUIVALENCE .2. CHILDREN

In a systematic replication of a study using college-student subjects (Pilgrim and Galizio, 1990), 5- to 7-year old children learned two con ditional discriminations (i.e., A1B1, A2B2, A1C1, and A2C2) in a two-c hoice arbitrary match-to-sample task and showed the emergence of two t hree-member equivalence classes (A1B1C1 and A2B2C2). Baseline conditio nal discrimination performances were quickly controlled by reversals o f the AC reinforcement contingencies (i.e., choosing Comparison Stimul us C2 was reinforced given Sample A1, and choosing C1 was reinforced g iven Sample A2) when the reversals were introduced in restricted basel ines. On reflexivity symmetry and transitivity/equivalence probes foll owing the reversal, there was some limited indication oi equivalence-c lass reorganization (i.e., A1B1C2 and A2B2C1) in keeping with the conc urrently performed baseline relations for 2 of 5 subjects, but the pre dominant pattern across probe trials was one of inconsistent condition al control. These findings suggest that, given similar challenges, equ ivalence-class performances may be more easily disrupted in young chil dren than in adults.