Effects of lexicality and regularity on reading aloud performance in aphasia

Objectives: The purpose of the study was to evaluate the reading ability of persons with aphasia (PWA) according to lexicality and regularity. Methods: Twenty individuals with aphasia and 20 age- and education-matched normal individuals participated in the study. Experimental stimuli were manipulated based on the lexicality and regularity of two-syllable structures at word-level. Accuracy (%) served as a dependent measure, and the types of error were analyzed. Results: For the reading accuracy, PWA performed significantly worse than the control group. Participants demonstrated greater difficulties in reading non-words and irregular words across the groups. The two-way interaction between group and lexicality was significant, indicating that PWA demonstrated greater difficulties in reading non-words than words compared to the control group. Regression analyses revealed that regular non-word condition accounted for 47.7% of the total variance as a significant predictor. In the error type analyses, the error ratio of regular non-word condition was 71.74%, which was greater than that of word condition, 28.26%. Regularization error was 14.75% in non-word condition and 9.36% in word condition. Conclusion: These results indicated that PWA demonstrated greater reading difficulties than the control group, and their performance was differentially affected by the lexicality. Lexicality seems to play a critical factor in differentiating PWA from the normal control group. The results are consistent with previous findings that suggested that non-word reading was more difficult than words. The current study suggested that overall severity of aphasia was predicted by regular non-word condition, which placed greater processing burden on grapheme-to-phoneme conversion.