Background The significance of imageability and concreteness as factors for lexical tasks in aphasic individuals is under debate. No previous treatment studies have looked specifically at training abstract words compared to concrete for improved lexical retrieval in patients with chronic aphasia. Aim The goal of the present study was to determine the efficacy of a treatment for lexical retrieval that is based on models of lexical processing by utilizing abstractness as a mode of complexity. It was hypothesized that training abstract words in a category will result in improvement of those words and generalization to untrained target concrete words in the same category. Training concrete words in a category, however, will result in the retrieval of trained concrete words, but not generalization to target abstract words. Methods & Procedures A single subject experimental design across participants and behaviors was used to examine treatment and generalization. Generative naming for three categories (church, hospital, courthouse) was tested during baseline and treatment. Each treatment session was carried out in five steps: (1) category sorting, (2) feature selection, (3) yes/no feature questions, (4) word recall, and (5) free generative naming. Results Although participant 1 demonstrated neither significant learning nor generalization during abstract or concrete word training, participants 2, 3, and 4 showed significant learning during abstract word training and generalization to untrained concrete words. Participants 3 and 4 were also trained on concrete words which they improved on but did not show generalization to untrained abstract words. Conclusions The results of the present experiment support our hypothesis that training abstract words would result in greater learning and generalization to untrained concrete words. They also tentatively support the idea that generalization is facilitated by treatment focusing on more complex constructions (Kiran & Thompson, 2003; Thompson, Shapiro, Kiran, & Sobecks, 2003).

Purpose The goal of this project was to examine if there was a principled way to understand the nature of rehabilitation in bilingual aphasia such that patterns of acquisition and generalization are predictable and logical. Methods Seventeen Spanish-English bilinguals with aphasia participated in the therapy experiment. For each participant, three sets of stimuli were developed for each language: (a) English Set 1, (b) English Set 2 (semantically related to each item in English Set 1), (c) English Set 3 (unrelated control items), (d) Spanish Set 1 (translations of English Set 1), (e) Spanish Set 2 (translations of English Set 2; semantically related to each item in Spanish Set 1), and (f) Spanish Set 3 (translations of English Set 3; unrelated control items). A single subject experimental multiple baseline design across participants was implemented. Treatment was conducted in one language whereas generalization to within and between-language untrained items was examined. Results Treatment for naming on Set 1 items resulted in significant improvement (ES > 4.0) on the trained items in 14/17 participants. Of the 14 participants who showed improvement, within-language generalization to semantically related items was observed in 10 participants. Between-language generalization to the translations of trained items was observed for 5 participants; whereas between-language generalization to the translations of the untrained semantically related items was observed for 6 participants. Conclusions The results of this study demonstrate within and between-language patterns that are variable across participants, these differences are indicative of the interplay between facilitation (generalization) and inhibition.

It has long been observed that, when confronted with an implausible sentence like The ball kicked the girl, individuals with aphasia rely more on plausibility information from world knowledge (such that a girl is likely to kick a ball, but not vice versa) than control non-impaired populations do. We here offer a novel hypothesis to explain this greater reliance on plausibility information for individuals with aphasia. The hypothesis is couched with the rational inference approach to language processing (e.g., Shannon, 1949;Levy et al., 2009;Gibson, Bergen & Piantadosi, 2013; cf. Bates, McDonald, MacWhinney & Appelbaum, 1991). A key idea in this approach is that to derive an interpretation for an input string, individuals combine their priors (about messages that are likely to be communicated) with their knowledge about how messages can get corrupted by noise (due to production or perception errors). We hypothesize that language comprehension in aphasia works in the same way, except with a greater amount of noise, which leads to stronger reliance on syntactic and semantic priors. We evaluated this hypothesis in an act-out task in three groups of participants (individuals with aphasia, older controls, younger controls) on two sets of materials: (a) implausible double-object (DO) / prepositional-phrase object (PO) materials, where a single added or deleted word could lead to a plausible meaning; and (b) implausible active-passive materials, where at least two added or deleted words are needed to arrive at a plausible meaning (Gibson, Bergen & Piantadosi, 2013). We observed that, similar to controls (e.g., Gibson et al., 2013), individuals with aphasia rely on plausibility to a greater extent in the DO/PO than in the active/passive alternation. Critically, however, as predicted, individuals with 3 aphasia rely less on the literal syntax overall than either of the control groups, and use their world knowledge prior (plausibility) in both the active/passive and DO/PO alternations, whereas controls rely on plausibility only in the DO/PO alternation. In addition, older persons and persons with aphasia made more errors on the DO structures (which are less frequent than PO structures) independent of plausibility, thus providing evidence for reliance on a syntactic prior, the more frequent structure.4

Recovery from aphasia, loss of language following a cerebrovascular incident (stroke), is a complex process involving both left and right hemispheric regions. In our study, we analyzed the relationships between semantic processing behavioral data, lesion size and location, and functional percent signal change from functional magnetic resonance imaging (fMRI) data. This study included 14 persons with aphasia in the chronic stage of recovery (six or more months post stroke) and eight healthy controls who performed semantic processing tasks of determining whether a written semantic feature matched a picture or whether two written words were related or not. Using region of interest (ROI) analysis, we found that percent signal change in left inferior frontal gyrus pars opercularis and pars triangularis, despite significant damage, were the only regions to correlate with behavioral accuracy. Additionally, the more the damage to LIFG, LMTG and AG/SMG, the higher the percent signal change in bilateral superior frontal gyrus, middle frontal gyrus, and anterior cingulate, suggesting that these regions appear to serve as an assistive network in the case of damage to traditional language regions. Relative to controls who showed mainly positive correlations in activation between and within LH and RH ROIs, patients showed positive and negative correlations. Specifically, the right inferior frontal gyrus pars orbitalis is presumed to serve a monitoring function. These results reinforce the importance of the left hemisphere in language processing in aphasia, and provide a framework for the relative importance of left and right language regions in the brain.

Developing language treatments that not only improve trained items but also promote generalization to untrained items is a major focus in aphasia research. This study is a replication and extension of previous work that found that training abstract words in a particular context-category promotes generalization to concrete words but not vice versa (Kiran, Sandberg, & Abbott, 2009). Twelve persons with aphasia (5 female) with varying types and degrees of severity participated in a generative naming treatment based on the complexity account of treatment efficacy (CATE; Thompson, Shapiro, Kiran, & Sobecks, 2003). All participants were trained to generate abstract words in a particular context-category by analyzing the semantic features of the target words. Two other context-categories were used as controls. Ten of the twelve participants improved on the trained abstract words in the trained context-category. Eight of the ten participants who responded to treatment also generalized to concrete words in the same context-category. These results suggest that this treatment is both efficacious and efficient. We discuss possible mechanisms of training and generalization effects.