The effects of semantic and gesture treatments on verb retrieval and verb use in aphasia

Background: Previous research has suggested that semantic plus gesture treatments are effective for aphasic noun retrieval deficits. However, there is a paucity of evidence concerning the efficacy of semantic or gesture treatments for aphasic verb retrieval deficits. As both verbs and arm/hand gestures represent movement concepts, gesture may well be a potent treatment for verb retrieval deficits. Aims: This study investigated the comparative effects of semantic, gesture, repetition, and combined semantic plus gesture treatments for verb retrieval deficits associated with chronic Broca's aphasia. Methods & Procedures: Three women with chronic Broca's aphasia and significant verb retrieval deficits participated in single-subject multiple-baseline across conditions designs. Two participants primarily evidenced a word-form verb retrieval deficit and one a semantic deficit. A total of 100 verb pictures were balanced for relevant lexical factors and divided into five groups of 20 items. Following 10 baseline trials, 20 treatment sessions aimed at improving verb production were completed. Three treatment conditions were simultaneously compared. Treatment of incorrectly named items involved production of an associated noun and the movement and location characteristics of the target verb. Gesture conditions involved production of an iconic gesture. Outcomes & Results: The participant with semantic-based verb retrieval deficit (MT) showed minimal response to any of the three treatments. Two participants with word-form impairments (KC and MW) demonstrated significantly improved verb retrieval skills and large treatment effects following all three treatments. KC and MW correctly used treated items in picture description and conversation tasks, and there was a modest amount of generalisation to untreated items. Combined semantic plus gesture treatment was superior for MW, but all three treatments were equally efficacious for KC. Conclusions: The findings support the use of multi-modal semantic treatments to improve verb retrieval in individuals with aphasic word-form verb retrieval deficits. Replication is required to achieve a stronger evidence base. Baseline error patterns may be useful in predicting response to treatment.