LEFT-LATERALIZED N170 RESPONSE TO UNPRONOUNCEABLE PSEUDO BUT NOT FALSE CHINESE CHARACTERS—THE KEY ROLE OF ORTHOGRAPHY S. E. LIN, a,b H. C. CHEN, c * J. ZHAO, a S. LI, a S. HE d AND X. C. WENG a,e * a Key Laboratory of Behavioral Science, Institute of Psychology, Chi- nese Academy of Sciences, Beijing 100101, China b Graduate University of Chinese Academy of Sciences, Beijing 100049, China c Department of Psychology, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China d Department of Psychology, University of Minnesota, MN 55455, USA e Center for Human Brain Research, Hangzhou Normal University, Hangzhou 310000, China Abstract—A negative event-related potential (ERP) compo- nent, known as N170, can be readily recorded over the pos- terior left brain region when skilled readers are presented with visual words. This left-lateralized word-related N170 has been attributed either to linguistic processes, particularly phonological processing, or to the role of orthographic reg- ularity, emphasizing a perceptual origin. This debate, how- ever, is difficult to resolve in the context of alphabetic scripts because of the tight relations between orthography and pho- nology. In contrast, Chinese characters have arbitrary map- pings between orthographic and sound forms, making it pos- sible to tease apart these two properties of visual words. We therefore addressed this issue by examining ERP responses to Chinese characters and three types of structurally matched but unpronounceable stimuli: pseudo-characters, false-characters, and stroke combinations. A content-irrele- vant color matching task was adopted to minimize potentially different top-down modulations across stimulus types. Re- sults show that, relative to false-characters and stroke com- binations, real- and pseudo-characters evoked greater N170 in the left posterior brain region. Critically, despite being unpronounceable, pseudo-characters produced the same amplitude and left-lateralized N170, just as real-characters. These results provide strong evidence that orthography rather than phonology serves as the main driver for the en- hanced and left-lateralized N170 to visual words. © 2011 IBRO. Published by Elsevier Ltd. All rights reserved. Key words: N170, Chinese character, orthography, phonol- ogy. Visual objects can evoke a prominent negative event-related potential (ERP) component peaking between 150 and 200 ms after stimulus onset, which is often referred to as N170 (Bentin et al., 1999; Maurer et al., 2008a; Rossion et al., 2003, 2004; Schendan et al., 1998). In skilled readers, the N170 evoked by visual words is significantly larger than that evoked by control stimuli such as strings of symbols and forms (e.g., Bentin et al., 1999; Maurer et al., 2005a,b). The word-related N170 is typically left-lateralized, contrary to the bilateral or right-lateralized N170 evoked by faces or objects (Brem et al., 2005; Dehaene, 1995; Rossion et al., 2003). Although there is a consensus that the enhanced and left- lateralized N170 effects for visual words reflect the neural change resulting from extensive experience with this partic- ular type of visual category (McCandliss and Noble, 2003), it remains challenging to identify the specific level at which this change occurs. While many researchers focus on the influ- ence of linguistic processing, suggesting, for example, that the left-lateralized N170 to visual words reflects automatic connections between orthographic forms and phonological representations (Proverbio and Zani, 2003; Maurer and Mc- Candliss, 2007), others emphasize a perceptual origin within the visual system, without additional involvement of phonol- ogy and other linguistic processes (Bentin et al., 1999; Wong et al., 2005). This issue is difficult to resolve in the context of sound- based scripts, because orthographic stimuli (i.e., words and their variants, such as pseudo- and non-words) may automatically activate phonological processing even in non-phonological tasks due to the systematic mapping between orthographic forms (e.g., letters and letter com- binations) and sounds. In contrast, in logographic Chinese, the mapping between visual and phonological forms is relatively arbitrary, thus allowing for investigation of visual form effects with minimal involvement of phonology (Chen and Juola, 1982). Interestingly, about 70% of Chinese characters have a left–right compound structure, consist- ing of two radicals with one on the left and another on the right. If the two radicals never occur together in a real character but each appears at a frequently appeared po- sition in the form of a compound character, this combina- tion is regarded as a pseudo-character (e.g., ), al- though it has no meaning or phonology of its own. If these two radicals or one of them are placed at unusual positions, this combination becomes a false-character (e.g., )(Ho et al., 2003; Yin and Butterworth, 1998). In the present study, we aimed to examine whether the enhanced and left-lateralized N170 to visual words is due to *Correspondence to: X. C. Weng, Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou 310000, China, or H. C. Chen, Department of Psychology, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China. Tel: +86-134-6631-5051 or +852-2609-6485; fax: +86-10-6483-2070 or +852-2603-5019. E-mail address: wengxc@psych.ac.cn (X. C. Weng) or hcchen@psy. cuhk.edu.hk (H. C. Chen). Abbreviations: ERP, event-related potential; VWFA, visual word form area. Please cite this article in press as: Lin SE, et al., Left-lateralized N170 response to unpronounceable pseudo but not false Chinese characters—the key role of orthography, Neuroscience (2011), doi: 10.1016/j.neuroscience.2011.05.071 Neuroscience xx (2011) xxx 0306-4522/11 $ - see front matter © 2011 IBRO. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.neuroscience.2011.05.071 1