Indices of Lexical Access During Idiom Comprehension

San Diego State University, San Diego CA

Investigators

Abstract

DESCRIPTION (provided by applicant): This project examines spoken language comprehension in individuals with aphasia, a language disorder acquired subsequent to stroke. There are several sub-types of aphasia, each with characteristic language impairments;this project specifically examines auditory sentence comprehension in Broca's aphasia. Prior research in the field has utilized both on-line methods, which are temporally-sensitive and examine the moment-by-moment cognitive processes of comprehension, as well as off-line methods, which are temporally- insensitive and examine the outcome of comprehension. From this prior work, a hypothesis has been put forward that an on-line lexical (word-level) processing deficit in Broca's aphasia underlies off-line comprehension impairments in this population. In particular, the current proposal investigates a theoretical assertion that lexical processing is delayed in Broca's aphasia, as compared to lexical processing in healthy listeners. The current proposal undertakes an investigation of the time course of lexical processing in Broca's aphasia by utilizing idiomatic phrases (IPs), which are argued to be long lexical items that have multiple meanings (literal and figurative). For instance, the IP 'hit the sack'is associated with a figurative meaning (i.e. 'to go to sleep'), but each word in this phrase also carries an independent literal meaning (i.e. 'strike'and 'bag'). IPs is used in the current study because prior research with unimpaired listeners indicates that these healthy individuals lexically process both the literal and the figurative meanings of an IP, but on slightly offset time scales. That is, typical listeners begin to lexically process the figurative meaning of an IP slightly prior to lexically processing the literal meaning. This temporal discrepancy motivates the current proposal, and will allow a close examination of the time course of lexical access in Broca's aphasia. This project embeds IPs in auditory sentence contexts and, using on-line methodology, examines moment- by-moment lexical processing in Broca's aphasia for the IP's meanings during auditory comprehension. The goals of this project are: 1) to determine whether lexical processing is delayed for one or both meanings of an IP in Broca's aphasia during auditory sentence comprehension;2) to question whether lexical items with multiple meanings (i.e. IPs) incite delayed lexical processing, or if lexical processing is inherently delayed;and 3) to investigate off-line comprehension of IPs in Broca's aphasia. The outcomes of the current project will inform theoretical models of language comprehension deficits in Broca's aphasia, by providing insight into the processing mechanisms that underlie these impairments. This project may also inform treatment of Broca's aphasia, by highlighting the specific elements of language (i.e. lexical processing speed) that should be targeted for remediation. PUBLIC HEALTH RELEVANCE: Aphasia, an acquired language disorder that is typically caused by a stroke, may affect over one million individuals in the United States. This disorder can impair the ways in which an individual understands and interacts with those around them, and has significant communicative, emotional, and financial consequences for patients and families. This project seeks to better understand language comprehension impairments in individuals with aphasia, and the findings will ultimately carry implications for treatment of the disorder.