Invited speaker : Merav Ahissar
Towards a neuro-computational account of skill acquisition – the case of reading expertise and its failure due to poor detection of sound regularities
Merav Ahissar (The Hebrew University, Psychology Department and ELSC Center for Brain Sciences, Israel)
Expertise is acquired by a gradual replacement of on-line computations with scheme-based memory retrieval. This is the case for both simple perceptual and complex cognitive tasks. However, such a training-based replacement requires acquisition of the task-relevant regularities. Testing simple tone discriminations, we found that dyslexics have difficulties in quick detection of basic sound regularities (e.g. mean frequency in the experiment). Testing reading, we found that dyslexics’ benefit from recent encounters with the same words, decays faster. Testing long-term acquired linguistic regularities (e.g. span for frequent versus infrequent syllables), we found the same impairment.
Searching for the neural mechanism underlying dyslexics’ poor regularity detection, we asked whether dyslexics’ adaptation mechanisms, associated with learning stimuli distribution, have abnormal dynamics. We found that dyslexics’ cortical adaptation to sounds (N1 and P2 components) decays faster, suggesting that their memory trace decays faster, integrating stimuli over shorter time constants.
We propose that poor inference mechanisms yield noisier and less reliable linguistic predictions in dyslexia, impeding dyslexics’ acquisition of expert-level performance in reading.
When: Tuesday, October 18th, 2016, at 16:00
Where: Montreal Neurological Institute, DeGrandpré Auditorium, MNI, 3801 University