An Associative Interpretation of the Indirect McCollough Effect

Following an induction procedure in which a coloured grid is alternated with a square of a complementary colour, subjects report colour after-effects on both the grid orientation present during induction and the orthogonal non-induced grid orientation. The after-effect reported on the induced grid orientation is called the McCollough effect (ME). The aftereffect reported on the non-induced grid orientation is called the indirect ME. There is evidence that the ME represents an instance of Pavlovian conditioning. The present results support a conditioning interpretation of the indirect ME and are inconsistent with interpretations of the indirect ME that attribute the phenomenon to special orthogonal coding mechanisms within the visual system.     

Establishing Arbitrary Stimulus Classes via Identity-matching Training and Non-reinforced Matching with Complex Stimuli

The present study investigated whether training on an identity match-to-sample task followed by non-reinforced matching probes with complex stimuli leads to the emergence of multiple arbitrary matching performances and arbitrary stimulus classes in preschool children. In Experiment 1, eight subjects were trained on a colour-matching task (A-A). Then they received tests with complex AB and AC colour-form stimuli (AB-A, B-AB; AC-A, C-AC). These tasks were designed to help subjects respond to both elements of each complex stimulus. Subsequent B-A, C-A, A-B, A-C, B-C, and C-B tests revealed that all subjects had acquired class-consistent colour-form and form-form relations. Experiment 2 examined whether these results could be replicated when subjects were encouraged to respond to the colour elements of some (AB) complex stimuli and to the form elements of other (AC) stimuli. The procedures were the same as in Experiment 1 except that during the first test only A-AB and C-AC tasks were used. Six of eight subjects demonstrated all tested relations.     

Emergent Simple Discrimination via Transfer from Differentially Reinforced S+ Stimuli: A Further Test of the Stimulus-Response Interaction Model

This study examined emergent form discrimination through contiguity of the forms (B stimuli) with colours (A stimuli) associated with different magnitudes of reinforcement. In Experiment 1, children were trained on two colour discriminations. In both, the colour stimuli had the same form: A1B1/A2B1 and A3B1/A2B1. Responding to A1/B1 was followed by three units of reinforcement, to A3B1 by one unit of reinforcement, and to A2B1 by no reinforcement. There followed five tests in which stimuli were presented without programmed consequences. These assessed: (1) the maintenance of accurate performance on the training tasks; (2) S+ preference (A1B1/A3B1); (3) stimulus generalization (A1B2/A2B3, A3B4/A2B5); (4) S+ preference again (A1B6/A3B6); and (5) transfer from the S+ colours to the forms (A4B2/A4B4). On the final test, seven of the eight subjects selected A4B2. Experiment 2 demonstrated that a preference for A4B2 also occurred when the S+ preference tests were omitted. This preference was also found when the total amounts of reinforcement associated with the S+ colours (A1 and A3) were the same (Experiment 3). These findings: (a) indicate that children can acquire new discriminations under non-reinforced conditions through contiguity with differentially reinforced S+ stimuli; (b) support the Stimulus-Response Interaction model (Smeets, 1993) for specifying transfer.