Typicality-based semantic treatment for anomia results in multiple levels of generalisation

Abstract

This study investigated the effects of typicality-based semantic feature analysis (SFA) treatment on generalisation across three levels: untrained related items, semantic/phonological processing tasks, and measures of global language function. Using a single-subject design with group-level analyses, 27 persons with aphasia (PWA) received typicality-based SFA to improve their naming of atypical and/or typical exemplars. Progress on trained, untrained, and monitored items was measured weekly. Pre- and post-treatment assessments were administered to evaluate semantic/phonological processing and overall language ability. Ten PWA served as controls. For the treatment participants, the likelihood of naming trained items accurately was significantly higher than for monitored items over time. When features of atypical items were trained, the likelihood of naming untrained typical items accurately was significantly higher than for untrained atypical items over time. Significant gains were observed on semantic/phonological processing tasks and standardised assessments after therapy. Different patterns of near and far transfer were seen across treatment response groups. Performance was also compared between responders and controls. Responders demonstrated significantly more improvement on a semantic processing task than controls, but no other significant change score differences were found between groups. In addition to positive treatment effects, typicality-based SFA naming therapy resulted in generalisation across multiple levels.

Keywords: Aphasia; Generalisation; Rehabilitation; Typicality.

Figure 1.

Results of logistic mixed-effects regression examining treatment effects. The full sample (a) and the responders (b) showed a higher likelihood of responding accurately to atypical (thin dashed line) and typical trained items (thicker dashed line) than monitored items (solid black line) over time, demonstrating a direct effect of treatment. The nonresponders (c) demonstrated a higher likelihood of responding accurately to atypical trained items (thin dashed line) only.

Figure 2.

Results of logistic mixed-effects regression with only untrained items in the model to examine generalization. For the full sample (a) and the responders (b), the likelihood of naming untrained typical items accurately (thin dotted line) was significantly greater than the likelihood of naming untrained atypical items (thick black line), supporting the CATE hypothesis and typicality effect. For nonresponders, there was no significant difference in the likelihood of naming untrained typical items versus untrained atypical items.

Figure 3:

Changes pre- to post-treatment in average accuracy on semantic and phonological tasks for the full sample (a), responder (b) and nonresponder (c) groups. Significant gains were seen on tasks of semantic and phonological processing post-treatment for the full sample and responder groups (* = significant at p < .05 level). Note: NN = No-Name Condition; NP = Name-Provided Condition; SCV = Superordinate Category Verification; SFV = Semantic Feature Verification; CCJ = Category Coordinate Judgment; SJ = Syllable Judgment; PV= Phoneme Verification; RJ = Rhyme Judgment

Figure 4:

Changes from pre- to post-treatment in average reaction time on the semantic and phonological tasks for the full sample (a), responder (b), and nonresponder (c) groups. Reaction times were faster on tasks of semantic processing post-therapy for the full-sample and responder analyses (* = significant at p < .05 level). Note: NN = No-Name Condition; NP = Name-Provided Condition; RJ = Rhyme Judgment; SJ = Syllable Judgment; PV= Phoneme Verification; CCJ = Category Coordinate Judgment; SCV = Superordinate Category Verification; SFV = Semantic Feature Verification

Figure 5:

Changes from pre- to post-treatment in average accuracy on standardized outcome measures of cognitive-linguistic function for the full sample (a), responder (b) and nonresponder (c) groups. Significant gains were seen on measures of global cognitive-linguistic functioning and naming ability post-treatment for the full-sample and responder group (* = significant at p < .05 level). Note: WAB-LQ = Western Aphasia Battery-Language Quotient; WAB-CQ = WAB-Cortical Quotient; WAB-AQ = WAB-Aphasia Quotient; CLQT-CS = Cognitive Linguistic Quick Test-Composite Severity; BNT = Boston Naming Test; PAPT = Pyramids and Palm Trees Test; PALPA 1 = Same-Different Nonword Minimal Pair Task (auditory); PALPA 51 = Word Semantic Association (written); NNB CN = Northwestern Naming Battery-Confrontation Naming subtest