Summary: Dyslexia and the failure to form a perceptual anchor
Merav Ahissar1,2, Yedida Lubin3, Hanna Putter-Katz2,6 & Karen Banai4,5
In a large subgroup of dyslexic individuals (D-LDs), reading difficulties are part of a broader learning and language disability.
Recent studies indicate that D-LDs perform poorly in many psychoacoustic tasks compared with individuals with normal reading
ability. We found that D-LDs perform as well as normal readers in speech perception in noise and in a difficult tone comparison
task. However, their performance did not improve when these same tasks were performed with a smaller stimulus set. In contrast
to normal readers, they did not benefit from stimulus-specific repetitions, suggesting that they have difficulties forming perceptual
anchors. These findings are inconsistent with previously suggested static models of dyslexia. Instead, we propose that D-LDs' core
deficit is a general difficulty in dynamically constructing stimulus-specific predictions, deriving from deficient stimulus-specific
adaptation mechanisms. This hypothesis provides a direct link between D-LDs' high-level difficulties and mechanisms at the level
of specific neuronal circuits.
Developmental dyslexia was first documented more than 100 years ago.
Yet the essence of the difficulties that impede reading acquisition in
5%10% of the population is still heatedly debated1. It is now largely
agreed that the majority of individuals for whom reading remains a
struggle have phonological impairments rather than difficulties in
visual identification of letter sequences2. Thus, most dyslexics
have difficulties in manipulating and accurately repeating sequences
of speech sounds. Still, it is not clear whether these phonological
deficits are the core difficulties or are manifestations of a broader