Litt, R. , Nation, K. & Watkins, K.
University of Oxford, UK
Previous research has established a relationship between poor reading and Paired Associate Learning (PAL), a task in which participants learn stimulus-response mappings. Whether this relationship results from differences in verbal learning, or the ability to establish orthography-phonology mappings, remains unclear. The current study investigated the hypothesis that children with dyslexia have specific impairments in crossmodal (visual-verbal, verbal-visual), but not unimodal (verbal-verbal, visual-visual) PAL. Forty-five children (15 dyslexic, 15 CA controls, 15 RA controls) aged 8-11 were matched for nonverbal intelligence and tested across four PAL conditions each with 6 stimulus pairs: Visual-verbal, verbal-verbal, visual-visual, and verbal-visual. Novel abstract symbols and nonwords were used, eliminating the role of previous learning/knowledge and allowing us to simulate the earliest stages of letter-sound learning. PAL was tested over four weeks, with one PAL condition per week to minimize interference between conditions. On day one of each week, participants completed a computerized PAL task, consisting of two presentation trials and five test trials with feedback. The next day, participants completed a delayed recall and yes/no recognition task. Data were analyzed using mixed factorial ANOVAs (comparing group and performance across conditions), and multiple regression (examining the relationship between PAL and reading ability). Children with dyslexia performed equally as well as CA controls in the nonverbal condition (visual-visual), but significantly lower in conditions with a verbal component (visual-verbal, verbal-verbal, verbal-visual). Performance patterns were similar to RA controls. Contrary to the hypothesis, performance was not selectively impaired in crossmodal PAL. However, the finding of impaired verbal-visual PAL, which required no verbal output, suggests that verbal response demand alone cannot explain the findings. Two alternative hypotheses, one of verbal domain deficits, and the other of an additive effect of verbal task demands and crossmodal PAL are discussed.