Implicit learning in control, dyslexic, and garden-variety poor readers.
Stoodley CJ., Ray NJ., Jack A., Stein JF.
Developmental dyslexia is diagnosed when children fail to acquire literacy skills despite adequate education and intellectual ability. There is evidence of impaired implicit learning in dyslexia, and it is possible that poor implicit learning in dyslexic children affects their acquisition of complex skills such as reading. To assess whether children with dyslexia show evidence of poor implicit motor learning, 45 dyslexic children completed a serial reaction time task (SRTT). Age-matched controls (n= 44) and nondyslexic poor readers ("garden-variety" poor readers, n= 20) were used as comparison groups. The inclusion of the garden-variety poor-reader group allows us to address the specificity of implicit learning deficits to dyslexics, as opposed to poor readers who do not have a discrepancy between their intellectual and literacy skills. There were no significant differences between the three groups in performance accuracy. However, whereas the controls and garden-variety poor readers showed good implicit learning (measured by a significant reduction in response times from a block of random to a block of sequenced trials), the dyslexic group did not. These data suggest that implicit motor learning deficits may underlie the laborious learning seen in developmental dyslexia. Because garden-variety poor readers were as able as control children to use the sequence cues to achieve better task performance, there may be differences in how garden-variety poor readers and dyslexic children acquire knowledge. This has important implications for remediation programs that are specific to children with dyslexia and for distinguishing among varieties of poor readers.