Article

It is commonly assumed that number reading can be intact in patients with pure
alexia, and that this dissociation between letter/word recognition and number
reading strongly constrains theories of visual word processing. A truly selective
deficit in letter/word processing would strongly support the hypothesis that
there is a specialized system or area dedicated to the processing of written words. To date, however, there has not been a systematic review of studies
investigating number reading in pure alexia and so the status of this assumed
dissociation is unclear. We review the literature on pure alexia from 1892 to
2010, and find no well-documented classical dissociation between intact number
reading and impaired letter identification in a patient with pure alexia. A few
studies report strong dissociations, with number reading less impaired than
letter reading, but when we apply rigorous statistical criteria to evaluate these
dissociations, the difference in performance across domains is not statistically
significant. There is a trend in many cases of pure alexia, however, for number
reading to be less affected than letter identification and word reading. We shed
new light on this asymmetry by showing that, under conditions of brief exposure,
normal participants are also better at identifying digits than letters. We suggest that the difference observed in some pure alexic patients may possibly
reflect an amplification of this normal difference in the processing of letters
and digits, and we relate this asymmetry to intrinsic differences between the two types of symbols.
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Langue : ANGLAIS