THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY
Department of Computer Science and Engineering
Department of Electronic and Computer Engineering
Human Language Technology Center
Molecular Neuroscience Center
Center for Chinese Linguistics
School of Humanities and Social Science
THE INSTITUTE FOR ADVANCED STUDY
DISTINGUISHED SPEAKER SEMINAR
Neurocorrelates of Reading Chinese Words in Texts without Word Boundaries: Evidence from the Educated Eyes to the Educated Brain
Prof. Ovid J. L. Tzeng
Institute of Linguistics, Academia Sinica
Institute of Neuroscience, National Yang Ming University
Date : 6 June 2007 (Wednesday)
Time : 16:00-18:00
Venue : Mr & Mrs Lee Siu Lun Lecture Theater (LTK)
To many scientists, one important question of this century is how the brain enables the mind in its various creative functions, including scientific thinking itself. During the 1990s, at the molecular level, neuroscientists unraveled a great deal about the brain's intricate, interconnected cascade of electrical impulses and chemical processes. Similarly, at the cognitive level, scientists, with the help of many newly developed techniques of visualizing the neuronal activities on-line, have also mapped much of the elaborate geography of the brain and traced its sensory and cognitive pathways. Advances have been made especially in the identification of how the brain uses discrete systems for various types of leaning and of how and where memories are stored. Moreover, in recent years, some plausible explanations have been offered for the nature of dream, emotion, and consciousness. A new scientific endeavor, dubbed the cognitive neuroscience, is making its way to solve the old mind-body problem. One of the important issues in the new science concerns with the brain activities during effective learning.
To assess the nature of the brain plasticity, I will discuss insight gained from experiments on learning to read Chinese texts. In particular, the concept of "wordness" in reading Chinese texts is explored using the data obtained from tracking the eye movements during reading and also from brain images of the so-called "visual word form area" during character identification. With respect to the patterns of eye movements during reading, our discussion will focus on the depth of parafoveal pre-processing in the comprehension processes during reading. Lack of physical cues for word boundaries in Chinese makes parafoveal word processing a critical issue under the general assumption that words are basic units in reading alphabetic texts. With a boundary paradigm established for eye movement experiments, whether the preview stimulus corresponded to a real word was manipulated. Targets with word previews, even unrelated, were more likely to be skipped than those with pseudoword previews, suggesting that words can be processed parafoveally. Stated more specifically, the lexicality of the parafoveal stimuli was activated and had an influence on the WHERE decision. Moreover, a follow-up experiment, with the preview stimuli having the same first character as that of the target, found that targets with same morpheme previews were fixated more briefly than those with pseudoword previews. This result suggested the parafoveal word and all morphemes associated with its constituent characters are activated initially, and only appropriate ones remain.
Such an "educated" eye-movement pattern in the Chinese readers suggests a highly plastic nature of learning to read at the neurophysiological level. It also implies a trainable neuro-circuitry of reading which learns to meet the cognitive demands imposed by the specific script-speech relationship embedded in a particular writing system. Thus, comparative neuroimages of literate brains across different writing systems would be important for our understanding of how an "educated" brain is organized neurologically to meet the challenges imposed by various specific linguistic contexts. From the eye-movement experiments mentioned above, we obtained convincing evidence for words as functional units in reading Chinese texts. The next question we should seek answers is whether there is a visual word form area in our brain which is activated during the reading of such a non-alphabetic text. We carried out a series of word (both single- and multiple-character word) identification and obtained brain images with fMRI as well as MEG facilities under appropriate methodologies.
With respect to the brain images of the word form area in the left hemisphere, our review of most previous imaging data show a definite activation in the left inferior temporal area for the identification of Chinese words, regardless of whether it is a single-character or a multiple-character word. Such a cross-script confirmation of a specific word form area in the neuro-circuitry of reading is important. However, more data from tasks other than reading is imperative for settling the specific vs. general processing controversy. Moreover, the patterns of information flow among the visual word form area, the phonological-semantic transformation area, and the orthographic-semantic mapping area need to be specified in terms of the temporal dynamics for every writing system.
In sum, both sets of results suggest that words are also basic cognitive units for reading non-alphabetic texts at both neurophysiological as well as cortical levels. There is much to be learned about the educational processes within the developing brain. Reading as a secondary linguistic activity offers an enlightening window for us to take a look inside the brain.
Needlessly to say, more will be learned from the genetic make-up to the developments of neuronal system, and to the cognitive capability of various behavioral manifestations. However, from a biological viewpoint, results from our laboratory as well as those of other laboratories can be interpreted in the following way: Our brain appears to enjoy a much richer brain plasticity in all aspects of human learning, including learning both spoken and written languages as well as other cognitive skills. From this perspective, the once rejected Whorfian hypothesis, which proposed the cultural diversity as the result of linguistic relativity, should be re-examined in terms of our changing view about brain plasticity. This can be done by asking some key questions of effective learning. First, what are the distinctions between natural development and cultural education with respect to brain development? Second, what factors are responsible for the mastery of right learning attitude and adequate emotional intelligence? Third, what characterize effective remedial programs for learning difficulty? Finally, how to promote self-motivation in the pursuit of general and specific knowledge?
Prof. Ovid J. L. Tzeng is a respected psychologist recognized for his work in cognitive neuropsychology and is known particularly for his extensive analysis of cognition and memory system. His Ph.D. Dissertation was honored in the "Creative Talent Award Program of the year 1972" by the American Institutes for Research.
Prof. Tzeng joined the faculty of Ohio University in 1972 and after two years moved to the University of California, Riverside (UCR). In that period, he created a research center for studies in speech recording process during reading, human information processing, bilingual speech perception, orthography and reading behaviors of dyslexics, and Chinese aphasia. In particular, he was the leading pioneer in the field of the Cognitive Neuroscientific Studies of Chinese Language. There were three papers published in Nature between 1976 and 1979 for his research work on the cognitive neuropsychology of Chinese language processing and that was considered an honor in the field of Psychology.
Prof. Tzeng has had a distinguished professional career that includes serving as Visiting Associate Professor at the Department of Linguistics, University of California, Berkeley; Visiting Associate Professor at the Haskins Laboratories and Yale University; Visiting Scientist at the Salk Institute for Biological Studies in San Diego; External Examiner for the Institute of Education, Singapore and the Chinese University of Hong Kong; Professor and Dean of the College of Social Sciences at the National Chung Cheng University; Professor and President of the National Yang-Ming University; Minister of Education, Taiwan; Director of the Taiwan International Graduated Program (TIGP); Vice President of the Academia Sinica.
He was awarded a National Award of Distinguished Scholarship of Ministry of Education, and the Special Lectureship in Cognitive Science by the National Science Council. Besides, he is the author of more than 100 scientific papers and also the consulting editor for many journals including Cognition: International Journal of Cognitive Science; Memory and Cognition, Psychological Research: An International Journal of Perception, ,Learning and Communication; Journal of Chinese Linguistics (UC-Berkeley Press), Chinese Journal of Psychology, Journal of East Asian Linguistics; and Educational Journal in Hong Kong.
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http://www.cs.ust.hk/~hltcLast updated: 2007.05.31 Dekai Wu