Hemispheric organization in disorders of development

ABSTRACT

A recent theoretical account posits that, during the acquisition of word recognition in childhood, the pressure to couple visual and language representations in the left hemisphere (LH) results in competition with the LH representation of faces, which consequently become largely, albeit not exclusively, lateralized to the right hemisphere (RH). We explore predictions from this hypothesis using a hemifield behavioural paradigm with words and faces as stimuli, with concurrent event-related potential (ERP) measurement, in a group of adults with developmental dyslexia (DD) or with congenital prosopagnosia (CP) and matched control participants. Behaviourally, the DD group exhibited clear deficits in both word and face processing relative to controls, while the CP group showed a specific deficit in face processing only. This pattern was mirrored in the ERP data too. The DD group evinced neither the normal ERP pattern of RH dominance for faces nor the LH dominance for words. In contrast, the CP group showed the typical ERP superiority for words in the LH but did not show the typical RH superiority for faces. These findings are consistent with the hypothesis that the typical hemispheric organization for words can develop in the absence of typical hemispheric organization for faces but not vice versa, supporting the account of interactive perceptual development.

KEYWORDS:

• Prosopagnosia
• N170
• developmental dyslexia
• face recognition
• word recognition
• hemispheric organization

Acknowledgements

We thank Amanda Robinson and Erez Freud for their thoughtful comments on the data analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by a grant from the National Science Foundation to MB and DCP (BCS-1354350), by a Grant from the Temporal Dynamics of Learning Center, SBE0542013 (PI: G. Cottrell; Co-PI: MB), by an National Institute of Health Medical Scientist Training Program Grant to EC, 5T32GM008208-26 (PI: Steinman), and an National Institute of Health predoctoral training grant (NIH 5T32GM081760-09 to EC; PI: Fiez, Co-PI: Holt).