Merger and expansion of equivalence classes via meaningful stimuli.

The present experiments evaluated the effect of meaningful stimuli on the inclusion of a set of extra-experimental meaningful pictures into equivalence classes using within- and between-subjects designs. There were 35 adult participants in total (NEXP1 = 22; NEXP2 = 13). In both experiments, participants were first trained on six baseline relations with abstract stimuli (A, B, and C) and assessed on the emergence of three 3-member equivalence classes. Next, they were trained on DA relations and assessed on the inclusion of the D stimuli and a set of meaningful pictures in the equivalence classes. In Experiment 1, D1 and D2 were meaningful written words and D3 was a written pseudoword. In Experiment 2, for 2 groups, D1, D2, and D3 were meaningful words; for another group, D1, D2, and D3 were pseudowords. In both experiments, participants formed the ABC classes and included the D stimuli in the classes. When D was a meaningful word, participants also included a set of pictures potentially related to the word in the ABC class established experimentally. The results have implications for the definition of meaningfulness and contribute to discussions on the impact of test arrangements on emergent responding.

A descriptive analysis of baseline and equivalence-class performances under many-to-one and one-to-many structures.

The purpose of the present experiment was to describe responding as a function of One-to-Many (OTM) and Many-to-One (MTO) training structures and identify baseline performances correlated with the accuracy level in tests for equivalence class formation. Participants were 42 adults assigned to either the MTO or the OTM groups, trained on 24 baseline relations, and assessed on the emergence of three 9-member equivalence classes. Participants in the MTO group presented similar frequencies of responses to each of the comparisons throughout baseline training. Also, the number of trials required to meet the baseline mastery criterion was negatively correlated with test accuracy. Participants in the OTM group presented more variable frequencies of responses to each of the comparisons (participants tended to select some of the comparisons less often than others at the beginning of the training). In addition, the number of reinforced responses to the node presented as a sample during training was positively correlated with the number of correct responses during testing for the OTM group. The experiment contributed to an in-depth stimulus control analysis of baseline and test performances, and its results have implications for understanding potential sources of variability between the training structures.

Generalization of equivalence relations from photos to objects by preschool children.

Generalized equivalence classes are stimulus classes that consist of equivalent stimuli and other physically similar class-member stimuli. The present study evaluated whether preschool children would form equivalence classes among photos of abstract objects (2D) and show equivalence generalization to the corresponding objects (3D), printed photos (2D stimuli), and to black-and-white drawn pictures (2D stimuli). Six typically developing children were taught arbitrary relations to establish three 3-member equivalence classes with 2D stimuli presented on a computer screen. AB-AC baseline relations (for half of the participants) and AB-BC relations (for the other half) were taught using a multiple-probe design to assess taught and tested relations. After class formation, three types of generalization probes were conducted: generalization to 3D stimuli, generalization between 2D (printed photos) and 3D stimuli, and generalization to drawn pictures (2D). All of the participants formed the equivalence classes. Two participants met the criterion for all three generalization probe types. Two participants presented mixed results across tests, and two participants did not exhibit equivalence generalization. The results demonstrated equivalence generalization from 2D to 3D stimuli in preschool children, although the variability across participants suggests that such generalization cannot be assumed a priori.