Priming is not all bias: Commentary on Ratcliff and McKoon (1997).

R. Ratcliff and G. McKoon (1997) reported a set of findings they claim are inconsistent with all prior accounts of long-term priming, including (1) a pattern of benefits and costs in an identification task suggestive of a bias interpretation of priming, and (2) a restriction on priming such that benefits and costs are only obtained when the alternatives in the forced-choice task are similar. Based on these and related findings, the authors developed a bias theory of visual word priming that is implemented in a mathematical model. However, it is shown that their empirical findings are ambiguous and can be explained more parsimoniously within more traditional frameworks. Furthermore, eight studies are reported that directly contradict their model. On the basis of these and related findings, it is argued that priming is best understood as a by-product of learning within perceptual systems whose main function is to categorize inputs. Visual word priming often reflects perceptual learning rather than perceptual bias: Reply to Ratcliff and McKoon (1997) Long-term priming is one of the more widely studied phenomena in cognitive psychology during the past 20 years (see Roediger & McDermott, 1993, for an extensive review that includes over 300 references on the topic since 1980). On the standard view, long-term priming reflects a facilitation in processing a stimulus as a consequence of having encountered the same stimulus in an earlier episode. So for example, participants are more accurate in identifying a quickly flashed word in a perceptual identification task if it was studied a few minutes or hours previously (e.g., Jacoby & Dallas, 1981). The longevity of this priming distinguishes it from various forms of short term priming phenomena -- such as semantic or masked priming...