The Nature of Word Frequency Effects on Perceptual Identification

Four experiments, using a study-test paradigm, examined the effects of event presentation frequency on perceptual identification. In each cycle, subjects studied a list with different items presented from one to four or more times, then received identification tests of studied and nonstudied items. Pseudoword repetition (Experiments 1 and 4) produced a priming effect, that is, enhanced identification for presented items, and a repetition effect, that is, incremental improvements in identification for repeated items. In contrast, word repetition (Experiments 2, 3, and 4) produced priming but not repetition effects, a pattern that was not due to learning asymptotes or scaling distortions. We conclude that presentation frequency effects act on at least two distinct processing paths, selected on the basis of processing and task demands. Under conditions of simple exposure, perceptual enhancement is mediated, for codified events like words, primarily by nodal activation, and, for noncodified events like pseudowords, by information accumulation.