Probabilistic category learning in developmental dyslexia: Evidence from feedback and paired-associate weather prediction tasks.

OBJECTIVE Developmental dyslexia is presumed to arise from specific phonological impairments. However, an emerging theoretical framework suggests that phonological impairments may be symptoms stemming from an underlying dysfunction of procedural learning. METHOD We tested procedural learning in adults with dyslexia (n = 15) and matched-controls (n = 15) using 2 versions of the weather prediction task: feedback (FB) and paired-associate (PA). In the FB-based task, participants learned associations between cues and outcomes initially by guessing and subsequently through feedback indicating the correctness of response. In the PA-based learning task, participants viewed the cue and its associated outcome simultaneously without overt response or feedback. In both versions, participants trained across 150 trials. Learning was assessed in a subsequent test without presentation of the outcome, or corrective feedback. RESULTS The dyslexia group exhibited impaired learning compared with the control group on both the FB and PA versions of the weather prediction task. CONCLUSIONS The results indicate that the ability to learn by feedback is not selectively impaired in dyslexia. Rather it seems that the probabilistic nature of the task, shared by the FB and PA versions of the weather prediction task, hampers learning in those with dyslexia. Results are discussed in light of procedural learning impairments among participants with dyslexia.