title: Auditory frequency discrimination in adults with dyslexia: a test of the anchoring hypothesis.
abstract: OBJECTIVE
  A recent hypothesis ascribes dyslexia to a perceptual anchoring deficit. Supporting results have so far been obtained only in children with dyslexia and additional learning difficulties, but the hypothesis has been argued to apply to all individuals with dyslexia.
  
  
  METHODS
  The authors measured auditory frequency discrimination thresholds in 54 young adults (native speakers of Dutch; 25 individuals with dyslexia; 29 age- and education-matched controls), with a 2-alternative forced-choice staircase paradigm. There were 2 conditions: 1 in which 1 tone in each pair had a fixed frequency across trials (standard), and 1 in which both tones varied in frequency (no standard). Presence of a standard stimulus allows the creation of a stimulus-specific representation in short-term-memory (perceptual anchor).
  
  
  RESULTS
  The standard condition yielded significantly lower discrimination thresholds in both controls and individuals with dyslexia; both groups benefited equally from the presence of an invariant stimulus.
  
  
  CONCLUSIONS
  There is no difference between this group of adults with dyslexia and controls in their capacity to form a perceptual anchor. The implication is that an anchoring deficit cannot be generalized to all cases of dyslexia.
authors.affiliation: Utrecht University, The Netherlands. F.N.K.Wijnen@uu.nl
authors.forename: Frank
authors.initials: F
authors.lastname: Wijnen
authors.forename: Astrid M L
authors.initials: AM
authors.lastname: Kappers
authors.forename: Leoni D
authors.initials: LD
authors.lastname: Vlutters
authors.forename: Sven
authors.initials: S
authors.lastname: Winkel
mesh_terms: D000293:Adolescent; D000328:Adult; D001309:Auditory Threshold / Q000502:physiology; D004410:Dyslexia / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007805:Language Development Disorders / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D010700:Phonetics; D011578:Psycholinguistics; D013063:Speech Discrimination Tests; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult