Lexical access in aphasia: impacts of phonological neighborhood density on accuracy of word production

Being able to think of and speak the words one wants to say is critical for timely, effective communication, and it is an ability that comes effortlessly to most of us. However, in speakers with aphasia, a language impairment due to a stroke, word retrieval difficulties (anomia) are very common, and tend to last long after the onset of the stroke. The nature of word retrieval difficulty also varies in different types of aphasia. In order to maximize the success of speech-language therapy for these individuals, it is important to understand a variety of factors which influence how easily and quickly individuals can produce words. According to one model of word retrieval, anomia is due to weakened connections within the individual’s mental store of words, resulting in speech errors. According to previous research, words with more “neighbors” (similar-sounding words, such as “bee”), appear to be easier to produce than words which are more unique in sound, such as “glove”. However, it is unclear if individuals with different breakdowns in the word retrieval process experience different effects when attempting to produce words with many neighbors compared to words with few neighbors. The aim of this project is to analyze the effect of word neighbors on naming accuracy in individuals with aphasia and different types of word retrieval breakdown. Twenty-two participants with various types and severities of aphasia named 200 single-syllable line drawings. The speech errors they made were categorized and analyzed. Word retrieval was difficult for individuals with all types of breakdown, but differences were found in the patterns of errors produced and the extent to which word neighbors facilitated production. Ways in which this information can improve treatments for anomia are discussed.