Associative Symmetry and Stimulus Class Formation in Humans: Are They Just Like Pigeons?

Associative symmetry is the phenomenon that organisms will respond to B-A (i.e., select A in the presence of B) after they effectively learned the relation A-B (i.e., select B in the presence of A). For a long time, it was assumed that associative symmetry emerges from direct bidirectional control between A and B established during A-B training. Recently it was demonstrated that associative symmetry in pigeons relies on indirect class formation (Urcuioli, 2008). In four experiments, we assessed associative symmetry in humans using a successive go/no-go matching-to-sample procedure. We demonstrate that, although humans are able to derive relations based on indirect class formation, this mechanism does not form the basis for their production of associative symmetry. Instead, we argue that associative symmetry in humans, unlike in pigeons, might reflect direct bidirectional control.status: publishe