Investigation of phonological, orthographic, and cross-modal integration differences in adults with and without dyslexia : a nonvocal nonword recognition task
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The purpose of this report was to describe the phonological, orthographic, and cross-modal deficits presented by young adults with dyslexia through a brief literature review, which proposes a new nonvocal nonword recognition task that analyzes these deficits. Previous research has supported the notion that individuals with dyslexia have an assortment of deficits, with phonological impairments being the most consistent and severe. There is controversy on whether orthographic skills are impaired or a particular residual strength in adults with dyslexia. Research has also shown that dyslexics demonstrate difficulties with cross-modal integration, which occur during transfer or connection between phonological and orthographical processes. The proposed nonvocal nonword recognition experiment assesses phonological and orthographic processing and the cross-modality performance in young adults with dyslexia using nonwords and requiring no verbal output. This task utilizes a matching format and specifically highlights the transfer between modalities by presenting a stimulus in one modality and four matching choices in the same or a different modality. The task includes 4 different conditions: auditory-auditory, auditory-visual, visual-auditory, and visual-visual. The target stimuli include systematically created nonwords, and the foil stimuli included nonword deviations (i.e., addition, substitution, and omission of phonemes) of the target nonwords. The pilot study included 2 young adults: one control (male, age 25) and one (male, age 26) who was diagnosed with childhood dyslexia. The results revealed similar patterns across participants in that both demonstrated difficulties on the tasks that relied on phonological memory and were at a higher difficulty level relative to the tasks that relied more on orthographic processing and were at a lower difficulty level. The participant with dyslexia performed significantly lower across all tasks and conditions than the control and showed difficulties for the tasks that relied more heavily on phonological memory. The adult with dyslexia also demonstrated poor awareness of the syllable/word shape as indicated by frequent errors of added phonemes to target words. The present findings from use of the nonvocal nonword recognition test suggest that young adults with dyslexia have significant phonological processing deficits and cross-modal integration deficits, specifically with transferring orthographic information into phonological form.