The modulation of stimulus structure on visual field asymmetry effects: The case of Chinese character recognition

Abstract

Recent research suggests that visual field (VF) asymmetry effects in visual recognition may be influenced by information distribution within the stimuli for the recognition task in addition to hemispheric processing differences: Stimuli with more information on the left have a right VF (RVF) advantage because the left part is closer to the centre, where the highest visual acuity is obtained. It remains unclear whether visual complexity distribution of the stimuli also has similar modulation effects. Here we used Chinese characters with contrasting structures—left-heavy, symmetric, and right-heavy, in terms of either visual complexity of components or information distribution defined by location of the phonetic component—and examined participants' naming performance. We found that left-heavy characters had the largest RVF advantage, followed by symmetric and right-heavy characters; this effect was only observed in characters that contrasted in information distribution, in which information for pronunciation was skewed to the phonetic component, but not in those that contrasted only in visual complexity distribution and had no phonetic component. This result provides strong evidence for the influence of information distribution within the stimuli on VF asymmetry effects; in contrast, visual complexity distribution within the stimuli does not have similar modulation effects.

Keywords:

• Divided visual field paradigm
• Optimal viewing position
• Visual field asymmetry
• Chinese character recognition

Acknowledgments

We are grateful to the Research Grant Council of Hong Kong (Project HKU 744509H to J. H. Hsiao). We thank Yan Yan Ting for her help on the preliminary study of this project. We thank the editor and two anonymous reviewers for helpful comments.

Notes

¹ Note that since semantic radicals usually have a larger combinability than phonetic radicals, in our right-heavy characters, the left component (the semantic radical) had a larger combinability than the right component (vice versa for the left-heavy characters). Note also that Cantonese and Mandarin share the same orthography and only differ in character pronunciation, and thus the orthographic properties of Chinese characters such as the functions of phonetic and semantic radicals and radical combinability apply to both Cantonese and Mandarin.

² Since the participants were all Chinese native speakers/readers, and the characters in the materials were of medium-to-high frequency usage, the participants all had high naming accuracy (97% on average), and thus the accuracy data were not analysed here (Hsiao & Liu, 2010; Hsiao & Shillcock, 2005).

³ The tracking accuracy of the T120 Tobii eye tracker is similar to that of other eye tracking systems currently available, such as the Eyelink II system (SR Research Ltd., Canada). Despite use of the eye tracker to ensure participants' fixations, there may still be noise introduced in exact positioning of fixations due to the limitation of the eye tracker. Using an eye tracker with better accuracy, resolution, and sampling rates can reduce the noise.

⁴ Here we reported the results of the analysis based on the average per condition per participant (i.e., subject analysis). Note, however, that all the effects reported here were also significant in the analysis based on the average per condition per stimulus (i.e., item analysis); effects that were significant in only one type of analysis were not reported.