Effects of phonological neighbourhood on the treatment of naming in aphasia

Abstract

Background: Phonological treatments to improve naming ability in aphasia focus on re-strengthening connections within the phonological system. Nonetheless, the efficacy of phonological treatments is still being explored with particular consideration of cognitive neuropsychological perspectives. Clinicians may also need to consider lexical factors that interact with the word retrieval process. Researchers have shown that phonological neighbourhood density influences normal language recognition and production, but limited evidence exists for how phonological neighbourhoods may affect the treatment of word retrieval deficits in individuals with aphasia.Aims: The present study explored if manipulating the emphasis on phonological neighbourhood during treatment has an effect on naming ability, particularly in an individual with predominantly phonologically based deficits. We hypothesised that training front- and end-matched words in a condition that emphasised phonological neighbourhood would result in greater naming improvements than training front- and end-matched words in a condition that does not emphasise neighbourhood.Methods & Procedures: In this case study, participant AH had a moderate phonologically based word naming deficit following a stroke. He produced phonemic paraphasias and neologisms in spontaneous speech and other spoken word production tasks. In treatment, AH was asked to name triplets of pictures of items that were phonologically related, sharing initial or final phonemes, or unrelated. Items were from either high- or low-density phonological neighbourhoods. High-density items were trained largely in the context of neighbours, therefore emphasising neighbourhood. Low-density items were not trained within a condition that emphasise neighbourhood. The treatment was administered for 9 weeks (27 sessions), with each condition, front-matched, end-matched and unrelated, trained for 8 consecutive sessions. AH’s naming accuracy on training words was assessed using a basic withdrawal design with three probe naming tests during the treatment phase and at 1-month post-therapy. Naming accuracy was also recorded during treatment sessions.Outcomes & Results: Front-matched words, in a condition that emphasises phonological neighbourhoods, had the greatest treatment effects, with a medium effect size when comparing pre- versus post-measures. A small treatment effect was observed for front-matched items where neighbourhood was not emphasised.Conclusions: Results suggest that front-matched triplets trained within a condition that emphasises phonological neighbourhoods may lead to the greatest treatment effect. Clinicians should be aware that stimulus parameters, such as phonological neighbourhood, may interact with the effectiveness of treatment protocols.