Initial training with difficult items does not facilitate category learning

Abstract

In the phenomenon of transfer along a continuum (TAC), initial training on easy items facilitates later learning of a harder discrimination. TAC is a widely replicated cross-species phenomenon that is well predicted by certain kinds of associative theory (e.g., Sutherland & Mackintosh, 1971). A recent report of an approximately-opposite phenomenon (i.e. facilitation by initial training on hard items, Spiering & Ashby, 2008) poses a puzzle for such theories, but is predicted by a dual-system model (COVIS; Ashby et al., 1998). However, across four experiments we present substantial evidence that Spiering and Ashby’s conclusions were in error. Their result appears to be a false positive and, as such, should not form part of the evidence base for COVIS, nor be considered as a counter-example to the pervasive TAC phenomenon.