Effects of Semantic Context and Word-Class on Successful Lexical Access

Abstract

Language production is ubiquitous in everyday life. A critical component of language production is the retrieval of individual words. In this thesis, we investigated the process of lexical access across six experiments that required participants to produce words in different contexts. First, we examined whether semantic relationships between proper names lead to competition during lexical access. Participants were asked to name celebrity pictures after either reading a famous or non-famous prime name or classifying a prime name as belonging to a famous or non-famous person. Results revealed that successful name retrievals decreased with increasing trial number. Within individual trials, tip-of-the-tongue states increased only after the classification of famous prime names. These findings indicate that the effects of competition from related proper names vary based on the particular semantic context in which they are retrieved. Next, we examined how the broader semantic context of sentences affects access to object names. It is widely accepted that highly constraining contexts can facilitate lexical access through predictive processing. We examined whether prediction during language processing still confers a benefit in situations where predictions were either almost correct or completely incorrect. In three experiments that investigated both language production and comprehension, we found a clear cost to incorrect predictions which we hypothesize may be used as an error signal in language learning to fine tune the language system. Finally, we investigated function word production using a task that required individuals to read aloud short paragraphs that contained errors on function words under distracting versus silent conditions. We found that background speech did not affect the likelihood that speakers would spontaneously correct the errors, but did increase non-target function word substitution errors. Overall, these studies support a framework in which lexical access is influenced by both word-class and semantic context at the point of retrieval.