Right hemisphere lateralization and holistic processing do not always go together: An ERP investigation of a training study

Abstract

Holistic processing (HP) and right-hemispheric lateralization both mark expertise in visual object recognition such as face and sub-ordinate object perception. However, counter-examples have been found recently: Experiences of selective-attention-to-parts such as writing experiences in Chinese characters reduced HP but increased right hemisphere lateralization. We investigated the association between HP and brain activities measured by event-related potentials (ERP) in participants trained to recognize artificially-created scripts using either whole-word or grapheme-to-phoneme approaches. Stronger N170 activities were found in both hemispheres in both training approaches. However, the two training approaches induced correlations in opposite directions between HP and the ERP signals in the right hemisphere: In the whole-word condition the HP effect increased, whereas in the grapheme-to-phoneme condition the HP effect decreased, with stronger right-hemispheric N170 activities. This demonstrates that HP and right hemispheric lateralization are separate processes that are likely associated with different perceptual mechanisms.