The neural and behavioural expertise markers of word recognition is modulated by the type of learning experiences

Abstract

Holistic processing (HP) and hemispheric lateralization are both expertise markers of object recognition. For example, HP and stronger right hemispheric lateralization is often associated with face and expertise in sub-ordinate object perception. However, experiences of selective attention to parts such as writing experiences of modulate HP in Chinese characters (Tso, Au, & Hsiao, 2014) and drawing experiences of faces (Zhou et al., 2011). Tso, Au & Hsiao (2013, 2014) revealed an initial increase in holistic processing of Chinese characters in beginners learning to read Chinese orthography, and suggested that sensorimotor reproduction of Chinese characters allows experts to be attentive to local orthographic structures of Chinese characters, which later reduced HP. Meanwhile, hemispheric lateralization is associated with the decoding strategy employed in object recognition, such as left hemispheric lateralization for reading alphabetic scripts and right hemispheric lateralization for reading logographic scripts. This thesis aims to investigate how perceptual expertise phenomenon is modulated by different types of learning experiences in two large-scale training studies. Study 1 investigated the perceptual changes, particularly in holistic processing and brain activities measured by event-related potentials (ERP) with electroencephalography (EEG), by training participants to recognize the same sets of artificially-created scripts using either whole-word (Logographic) or grapheme-to-phoneme (Alphabetic) approaches. A stronger N170 activation was found in both hemispheres in across both training approaches. Though the type of training approaches induced opposite directions in correlations between holistic processing and the ERP signals in the right hemisphere: In the logographic condition, the HP effect increased with stronger right-hemispheric N170 activities; while the direction of this correlation is reversed in the alphabetic condition. This demonstrates that HP and hemispheric lateralization are separate processes that are associated with different perceptual mechanisms. Study 2 aims to investigate whether second-language Chinese learners explicitly reconstructing Chinese characters with the utilization of character component stickers would induce similar effects as writing experience – leading to a perceptual change in Chinese character recognition. We found that both training through component-learning enhanced orthographic awareness and holistic character processing much more strongly than training approaches through whole-character recognition and character copying. It seems that orthographic awareness—the formation of a mental categorical representation of Chinese character—enhances HP, which is the initial stage of the development of expertise in Chinese character recognition. Thus, it is argued that the increase in holistic mental representation of Chinese characters among beginning learners might mark the initial stage of acquiring expertise in Chinese character recognition. Study 2 also revealed that attention to local character components alone through the process of writing Chinese characters is insufficient to explain the reduced in holistic processing in experienced writings, suggesting a unique role in the sensorimotor property of writing in modulating our visual perception. The result of this training study also suggests character reconstruction through component learning as an alternative Chinese character learning strategy, in addition to extensive writing and copying, to benefit emergent Chinese readers.