Phonotactics, density, and entropy in spoken word recognition

Previous research has demonstrated that increases in phonotactic probability facilitate spoken word processing, whereas increased competition among lexical representations is often associated with slower and less accurate recognition. We examined the combined effects of probabilistic phonotactics and lexical competition by generating words and nonwords that varied orthogonally on phonotactics and similarity neighbourhood density. The results from a speeded same-different task revealed simultaneous facilitative effects of phonotactics and inhibitory effects of lexical competition for real word stimuli. However, the nonword stimuli produced an apparently anomalous pattern of results. In a subsequent experiment, we identified the source of this anomaly by estimating behaviourally the specific lexical competitors activated by our nonwords. Our results suggest that, under specific circumstances, neighbourhood density and probabilistic phonotactics may combine to produce non-additive or synergistic effects of lexical competition on processing times.