Symbolic representation in animals: Emergent stimulus relations in conditional discrimination learning

Abstract

When two initially unrelated stimuli are associated with the same event (e.g., many-to-one conditional discriminations), an emergent relation can develop between those stimuli, allowing them to be interchangeable in other contexts. The source of the emergent relation appears to be a common representation of the two stimuli, and the nature of the representation may be retrospective, involving one of the initial stimuli (probably the stimulus that first enters into association). These emergent relations have been implicated in the establishment of stimulus equivalent relations. However, the failure to find strong evidence for other emergent relations thought to be involved in stimulus equivalence (Sidman, 1990; e.g., bidirectional associations, transitive relations, and functional equivalence associated with one-to-many conditional discriminations) suggests that the mechanisms underlying the emergent relations found using transfer designs following many-to-one training are different from those presumed to underlie stimulus equivalence. On the other hand, evidence for the common representation of stimuli associated with the same arbitrary event extends the nature of those representations beyond those well-established effects found when the common events are biologically important (e.g., the differential outcomes effect).