Frontiers in Psychology (May 2015)
Feasibility of A Novel Treatment of Abstract Verbs in Aphasia and Apraxia of Speech
Abstract
Introduction Models of sentence meaning emphasize the central role of the verb (Fillmore, 1968; Miller, 1972). These models are the theoretical basis of language production treatments for persons with aphasia such as VNeST (Edmonds, Nadeau, & Kiran, 2009) and “verb is core” treatment (Loverso, Selinger, & Prescott, 1979). However, these treatments have focused on concrete verbs, despite evidence pointing to the frequency of abstract verbs in spoken language (Renvall, Nickels, & Davidson, 2013) and recent evidence supporting the trainability of abstract concepts in persons with aphasia (Kiran, Sandberg, & Abbott, 2009). This study was designed to examine the efficacy of a novel treatment on production of sentences with abstract verbs, in two persons with nonfluent aphasia and apraxia of speech (AOS). Methods Participants Two patients with chronic Broca’s aphasia and AOS due to CVA were enrolled as participants. Extensive pretreatment testing was performed and will be discussed. This testing included assessments of argument structure production, abstract versus concrete lexical access, sentence repetition, speech rate, and narrative discourse. Treatment Description The treatment was largely based on VNeST (Edmonds et al., 2009). Due to lack of imageable stimuli, written and verbal models of the target word were given, along with a request for a sentence with subject and object arguments. Elements of RET (Kearns, 1985) were added to facilitate expansion of initial attempts. Suggestions for expansions were predominantly taken from a corpus (Davies, 2008-2012) to increase ecological validity of practiced sentences. Also, a contrastive stress exercise was included as an AOS treatment component to provide additional motor practice and facilitate flexibility of speech motor plans. Treatment was administered three times per week by certified SLPs and a supervised clinical fellow. Experimental Design The experimental design was a multiple baseline single-subject design across behaviors and participants. Dependent Measure Treatment probes were conducted prior to each second treatment session. Probes included written and verbal models of the target verb, along with an instruction to create a sentence with the target verb that included a “doer” (subject) and an object. Complete instructions will be provided. Probes were scored based on a novel system that emphasized semantic relatedness and plausibility of arguments and order of sentence elements. Stimuli Lexical verbs with high frequencies (Brysbaert & New, 2009) and SVO argument structures were selected as stimuli. Concreteness ratings (Brysbaert, Warriner, & Kuperman, 2014) were used to sort verbs into three abstract lists and one concrete list. Treatment was intended for two of the abstract lists, with the other lists for measuring response generalization. Results Results were been obtained for the first of two planned treatment phases for both participants. Results indicated improved sentence production attributable to the treatment for one of the two participants. The Conservative Dual Criterion (CDC; Swoboda, Kratochwill, & Levin, 2010) was used to aid in visual inspection of graphed probe data. These results indicate the feasibility of the treatment for increasing sentence production with abstract verbs in persons with chronic aphasia and AOS.
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