Transfer and Stimulus Equivalence Classes Derived From Simultaneously Presented S+ and S- Stimuli

Studies on equivalence have shown that after being trained on multiple arbitrary match-to-sample tasks (e.g., A-B, A-C), verbal humans frequently match all directly and indirectly linked stimuli with one another (e.g., B-C, C-B) without direct training (Barnes & Holmes, 1991; Fields, Adams, Verhave, & Newman, 1992; Sidman, 1992). Similar relations may also be obtained through stimulus contiguity, temporal contiguity (first A1 then B1, thus A1-B1) and spatial contiguity (A1 together with B1, thus A1-B1). Specifically, these studies showed that when stimuli are added to or are presented with stimuli participating in conditional or simple discrimination tasks, the new stimuli take on the functions of, and become conditionally related to, the stimuli to which they were added and all other same-class stimuli (Dube, McIlvane