Different letter-processing strategies in diagnostic subgroups of developmental dyslexia.
Normally reading adults (N = 15) and primary school children (N = 24) and two diagnostic subgroups of children with developmental dyslexia (N = 21)-all native German speakers-performed a successive same-different task with pairs of letters and nonletters (pseudoletters or geometrical shapes). The first item of a pair was always presented on its own, and the second either on its own or surrounded by a congruent or incongruent nontarget shape. Adults showed congruence effects with nonletters but not with letters, and children with both types of stimuli. Frequent-word reading-impaired dyslexics (N = 11) in addition showed dramatically slower overall reaction times. Nonword reading-impaired dyslexics (N = 10) showed congruence effects with nonletters but negative congruence effects with letters. The results support the notion that normal readers have established a special visual processing strategy for letters. Processing speed rather than reading expertise seems crucial for this strategy to emerge. The contrasting effects between subgroups of dyslexics reveal specific underlying deficits.
Lachmann
Thomas
T
University of Kaiserslautern, Department of Psychology II, Kaiserslautern, Germany. lachmann@rhrk.uni-kl.de
van Leeuwen
Cees
C
D000328:Adult; D002648:Child; D004410:Dyslexia / Q000503:physiopathology / Q000523:psychology*; D005556:Form Perception; D006801:Humans; D007802:Language; D007858:Learning; D009949:Orientation; D010364:Pattern Recognition, Visual; D011930:Reaction Time; D011932:Reading; D012016:Reference Values; D014825:Vocabulary