Vicari and colleagues assessed whether ~11-1/2-year-old Italian children identified as having dyslexia (using a discrepancy diagnosis) differed from their normal reading agemates on two tasks selected to tap different types of learning but free from reading. Here’re my notes from a first reading of the study.
On a serial-reaction-time task, children pressed the one of four keys that corresponded to a lit square in an array of four squares on a computer display; on some sets of trials the order of squares lit was essentially random but on other sets of trials, the squares were lit in a sequence. The dyslexic children responded more slowly that their non-disabled peers overall and made more errors; more importantly, they showed little or no improvement over time when the pattern was predictable, but there was minimal difference when the pattern was random.
On a mirror-drawing task, the children draw a star, staying within margins defining the outline of the star; however, an apparatus made it possible for them to see the results of their drawing in an upside-down image only. They drew as many stars as they could within 10-minute sessions and repeated the task four times spread over two days. On average, the dyslexic group drew fewer segments correctly and made more errors (bumps into the walls), especially on the second day, but they didn’t make proportionally more errors.
This study is important because it shows differences between the groups on learning tasks that are relatively free from the language skills that undergird reading. The children with dyslexia didn’t learn the patterns as readily as their agemates and didn’t learn to modify their drawing over time as well as those peers. This study is helpful in revealing differences between normal and poor readers in the acquisition of sequential skills, but it can perforce only tell part of the story, because a critical foundation for reading is mastery of the alphabetic principal, a language competency. However, these results do not refute the position that children with dyslexia (based on discrepancy) do not differ in important ways from those who have reading problems but do not have discrepancies between their ability and achievement; that question was not tested here.
Vicari, S., Finzi, A., Menghini, D, Marotta, L., Baldi, S., & Petrosini, L. (2005). Do children with developmental dyslexia have an implicit learning deficit? Journal of Neurology, Neurosurgery, and Psychiatry 76, 1392-1397.
Link to the abstract for the Vicari et al. study.
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