Lexical inhibition and attentional allocation during speech perception: Evidence from phoneme monitoring

The TRACE model (McClelland & Elman, 1986) predicts lexically-driven inhibition at the phonemic level. This is due to the combination of top-down excitatory connections from this lexical to the phonemic level, and inhibitory connections between competing units within the phonemic level. Frauenfelder, Segui, and Dijkstra (1990, Experiment 2) tested this prediction hi French and found no evidence of such inhibition. Experiment I of the current study replicated their results with English stimuli: Instead of having longer reaction times (RTs), targets in Inhibiting Nonwords (INWs) were detected just as fast as targets in control nonwords. Our Experiment 2 improved the design of the original experiment by adding a more appropriate: control condition, increasing the number of critical items, and employing balanced target locations and conditional target probabilities. Under these conditions, RTs to INWs were significantly faster than baseline RTs, an effect opposite in direction to the hypothesized inhibition. Experiment 3 used a dual-task paradigm to examine the attentional demands of processing different types of nonwords. In addition to performing the phoneme monitoring task as before, subjects also monitored a pure tone for frequency modulations. The RT advantage for INWs was replicated in this experiment for both phoneme and modulation targets. In Experiment 4 we replicated the: INW advantage for both phoneme and modulation targets, and found that the advantage disappeared for stimuli that carried both types of targets. The results suggest that both lexical inhibition and attentional allocation affect phoneme perception; their interaction can mask the effect of each. (C) 1997 Academic Press.