Investigation of the effects of semantic neighbours in aphasia: a facilitated naming study

Background: It is well established that word retrieval can be improved in people with aphasia. However, there has been little research regarding the influence of specific word properties on the success of such treatment. Aims: This study aimed to better understand the mechanisms supporting naming treatment effects in aphasia, by exploring effects of word-specific semantic neighbourhood variables (based on featural overlap or on association strength) on the outcomes of a facilitation task. Methods And Procedures: Two individuals, one with primarily lexical-semantic difficulties (SJS) and one with primarily lexical difficulties (DEH) participated. Their picture naming performance was assessed before and after a facilitation task in which each target word was repeated in the presence of the corresponding picture. Outcomes And Results: Both participants showed improved naming following the facilitation task. However, for DEH, inhibitory effects of words with many semantic neighbours were enhanced by the facilitation task. For SJS, in contrast, targets with a strongly associated word in the lexicon were less likely to result in a semantic error compared to those with an associate of weaker association strength. Conclusions: It is hypothesised that individuals like DEH, with lexical retrieval impairments, may show increased sensitivity to neighbourhood density, whereas individuals like SJS, with an impairment of the links between semantics to lemmas, may show sensitivity to other neighbourhood measures that are more likely to be encoded at the semantic level.