On the locus of the word frequency effect in visual word recognition

Abstract The pattern of factor effects on response time (RT) performance in multi-factor experiments provides a powerful technique for inferring the structure of underlying mental processes. The results of the present lexical decision experiment show that additive effects of stimulus quality and word frequency are observed in mean RTs, variances, and the exGaussian parameters of the RT distribution. These findings are consistent with the conclusion that word frequency and stimulus quality affect separate stages of processing. This is consistent with the conclusion that word frequency effects reflect mapping operations between stages, but, when taken in conjunction with other reports in the literature, is inconsistent with the received view in many activation models that word frequency exerts its effect within the word detector level of representation. Resume Le schema des effets du facteur sur l'execution du temps de reponse (TR) dans les experiences a multiples facteurs fournissent une technique efficace pour fixer la structure des processus mentaux sous-jacents. Les resultats de la presente experience de decision lexicale montrent que les effets additifs de la qualite du stimulus et de la frequence du mot sont observes dans les TR moyens, les variances et les parametres ex-gaussiens de la distribution du TR. Ces conclusions confirment que la frequence du mot et la qualite du stimulus influencent les phases separees du traitement. Elles confirment egalement que les effets de la frequence du mot refletent les operations de correspondance entre les phases, mais, lorsque comparees a d'autres rapports, les conclusions ne correspondent pas a la vision etablie dans plusieurs modeles d'activation qui veut que la frequence du mot exerce ses effets au niveau de representation du detecteur du mot. It is well established that a word's frequency of occurrence in printed English is a strong determinant of performance in word recognition tasks such as lexical decision. For example, high frequency words such as "CAT" are typically recognized more quickly than lower frequency words such as "VAT" (e.g., Forster & Chambers, 1973; Frederiksen & Kroll, 1976; see also Monsell, 1991, for a review). One account of this word frequency effect is given by a number of models in the Activation class. Thus, models such as Morton's (1969) logogen model and variants of McClelland and Rumelhart's (1981) interactiveactivation model (e.g., Coltheart, Curtis, Atkins, & Haller, 1993; Grainger & Jacobs, 1996) all assume a word level of representation in the form of orthographic and phonological word detectors for each word the reader knows. These word detectors accumulate activation over time, and both models assume that low frequency words take longer to reach a threshold than do high frequency words. The models differ in that the interactive-activation model assumes that high frequency words start with a higher resting level of activation than do low frequency words whereas the logogen model assumes a common resting level of activation but different recognition thresholds for high and low frequency words One difficulty with the activation explanation is that a simple main effect of word frequency in lexical decision does not allow one to determine the locus of the effect; it merely informs us that word frequency affects performance in this task. A number of investigators have therefore applied Sternberg's (1969) additive factors logic to this issue by manipulating word frequency in conjunction with other factors that affect performance in lexical decision because predictions can be derived from the models as to how the effects of these factors on response time (RT) should combine (e.g., Becker & Killion, 1977; Besner & Smith, 1992; Besner & Swan, 1982). WORD FREQUENCY, STIMULUS QUALITY, AND CONTEXT It is well documented that stimulus quality affects word recognition: Clearly presented stimuli are recognized more quickly than degraded ones. …