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.
Bibliographical noteFunding Information:
We thank M. Nahum, M. Shovman, A. Rokem and S. Greenberg for their help at various stages of this project. We thank S. Hochstein and E. Ahissar for comments on the manuscript. This study was supported by the Israel Science Foundation–Center of Excellence Grant, the Volkswagen Foundation and the Israeli Institute for Psychobiology.