Emergent simple discrimination in children: transfer of stimulus control under non-reinforced conditions

Children's emergent relations of equivalence using stimuli with opposite verbal labels: Exclusion and minimal training conditions

The present study examined different conditions under which exclusion responding in conditional discrimination tasks would generate emergent equivalence relations in young children based on shared relationships with verbal labels. Both visual stimuli (Sets A, B, C, and D) and auditory stimuli (spoken words, Set N: N1 "correct"; N2: "incorrect") were used. Following a pilot study, three experiments were conducted, each involving eight preschool children. These experiments systematically investigated under which conditions responding by exclusion (i.e., responding away from a designated S^- comparison in a matching to sample context) would generate sufficiently stable sample-S⁺ relations for arbitrary stimulus classes to establish. The results showed that young children's exclusion responding under test conditions will only contribute to arbitrary stimulus class formation and expansion when training has already established two arbitrary stimulus classes involving at least two stimuli each. For young children to demonstrate emergent conditional discrimination performances that are indicative of the formation of equivalence relations, it is necessary to have training and/or reinforced exposure to both S⁺ and S^- control elements required for deriving the appropriate emergent relations with at least two conditional relations involving different samples. These findings not only contribute to existing research and theory on the conditions under which exclusion responding may contribute to fundamental language and learning processes, they also contribute to the experimental predictability of emergent conditional matching behaviours in preschool children by further unravelling the conditions under which emergent matching based on exclusion generates arbitrary conditional relations of equivalence.

Role of stimulus-stimulus pairing in matching-to-sample procedure: cross-species comparison of humans and pigeons

The present experiment examined whether, in a matching-to-sample (MTS) procedure, a relation between two stimuli, a sample and a comparison, could be established as a result of just stimulus-stimulus pairing, even if back up reinforcers were never provided for the conditional relation between the sample and comparison stimuli, but rather only for the comparison stimulus. A procedure called "pseudo matching-to-sample" was used in which, when S1 was presented as a sample stimulus, two comparison stimuli (C1 and C2) were presented, and only responses to C1 were reinforced. Conversely, when S2 was presented, only responses to C3 (and not C4) were reinforced. In other words, organisms experiencing this procedure could discriminate C1 from C2, and C3 from C4, by simple discrimination without regard to the conditional sample stimuli. In order to examine cross-species differences, responding by humans in this procedure was compared to that by pigeons. Although the humans developed a discriminative function for the sample stimuli, that is, the humans' responding was affected by both the sample stimuli and the reinforcers, responding by the pigeons was affected solely by the reinforcers. These data suggest that, in this procedure, humans (but not pigeons) are able to learn relations among stimuli simply as a result of stimulus-stimulus pairing.

Concept formation based on the relations among values of multi-component figures

A complex discrimination procedure was used to test class formation with multi-component figures in college students. First, selections of a red-+45 degrees -oriented rectangle (A1B1) instead of a red -45 degrees -oriented rectangle (A1B2) and of a green -45 degrees -oriented rectangle (A2B2) instead of a green-+45 degrees -oriented rectangle (A2B1), were reinforced. Second, selections of a +45 degrees -obtuse-angle-white hexagon (B1C1), instead of a +45 degrees -two-acute-angle hexagon (B1C2) and of a -45 degrees -two-acute-angle hexagon (B2C2), instead of a -45 degrees -obtuse-angle hexagon (B2C1), were reinforced. Subsequent tests with figures A1B1 and A2B1, A2B2 and A1B2, B1C1 and B2C1, and B2C2 and B1C2 demonstrated selection of the same figures as in training. Other tests with a novel figure compounded by color A1 and form C1 and a novel figure compounded by color A1 and form C2, or a novel figure compounded by A2 and C1 and a novel figure compounded by A2 and C2 demonstrated consistent selection of figures A1C1 and A2C2. A final test with figures A1C1 and A2C1, or with figures A2C2 and A1C2 also showed consistent selections of the same figures -A1C1 and A2C2. The resulting classification among selected and non-selected figures cannot be based on particular properties of the selected figures, or in a combination of a particular set of those properties, because both selected and non-selected figures were compounded by identical values. Instead, the participants selected the figures with two values of the same set (A1,B1, or C1, or A2,B2 or C2). Thus, these results demonstrated categorization based on the relations among the values of the figures. Therefore, these results have important implications for the study of concept formation.

Delayed matching to complex samples and the formation of stimulus classes in children

In two experiments (ns = 3 plus a previously tested child, and 2, respectively), children learned delayed matching with complex samples, each consisting of a form and a printed nonsense word. Forms or printed words were comparison stimuli. For form comparisons, selecting the form identical to that in the preceding sample was reinforced. For printed word comparisons, selecting the word identical to that in the preceding sample was reinforced. During testing, the children then matched the forms and printed words to one another. In subsequent training, the samples were (a) old forms combined with new words or (b) old words combined with new forms. Novel matching performances among forms and words appeared across these training phases. Word-form contiguity in a matching-to-sample context may contribute to the formation of classes of stimuli that may be equivalent.