Onset density and inhibitory effects on lexical access in speech production

Lexical access in speech production involves multiple processing stages, beginning with the mental generation of a target concept and ending with a speaker's articulation of the target word. The current study aimed to explore the influence of competition and inhibition on the process of lexical access. In particular, the position of phonological overlap between a target word (e.g., lip) and its neighbors (e.g., lid vs. sip) was investigated for its influence on picture naming. It was hypothesized that greater inhibitory effects and slower response times in participants' naming would be observed for target words that have a predominance of neighbors which are onset related compared to those which are rhyme related. In addition, it was predicted that there would be a strong relationship between performance on the naming task and several inhibition tasks due to the common role of inhibition across tasks. Twenty-five native English participants completed a picture naming task, two language based inhibition tasks, and two non-language inhibition tasks. Participants' response times were recorded for incongruent/dense and congruent/sparse trials, and mean difference scores were examined to determine the inhibition effect sizes. The results showed that response times for dense onset trials were significantly slower than sparse onset trials, thereby supporting the first hypothesis. Inter-task correlation results, however, did not provide support for the second hypothesis that inhibition capacity would be common to different tasks. Factors such as varying task characteristics, modality of stimulus presentation, length of testing session, task counterbalancing, perceived task difficulty, and allocation of cognitive effort are discussed as having contributed to the lack of significant correlations.Medicine, Faculty ofAudiology and Speech Sciences, School ofGraduat