The role of multiple-exemplar training and naming in establishing derived equivalence in an infant.

The conditions under which symmetry and equivalence relations develop are still controversial. This paper reports three experiments that attempt to analyze the impact of multiple-exemplar training (MET) in receptive symmetry on the emergence of visual-visual equivalence relations with a very young child, Gloria. At the age of 15 months 24 days (15m24d), Gloria was tested for receptive symmetry and naming and showed no evidence of either repertoire. In the first experiment, MET in immediate and delayed receptive symmetrical responding or listener behavior (from object-sound to immediate and delayed sound-object selection) proceeded for one month with 10 different objects. This was followed, at 16m25d, by a second test conducted with six new objects. Gloria showed generalized receptive symmetry with a 3-hr delay; however no evidence of naming with new objects was found. Experiment 2 began at 17m with the aim of establishing derived visual-visual equivalence relations using a matching-to-sample format with two comparisons. Visual-visual equivalence responding emerged at 19m, although Gloria still had not shown evidence of naming. Experiment 3 (22m to 23m25d) used a three-comparison matching-to-sample procedure to establish visual-visual equivalence. Equivalence responding emerged as in Experiment 2, and naming emerged by the end of Experiment 3. Results are discussed in terms of the history of training in bidirectional relations responsible for the emergence of visual-visual equivalence relations and of their implications for current theories of stimulus equivalence.