Poster C15, Friday, August 17, 10:30 am – 12:15 pm, Room 2000AB
Word Inversion Sensitivity as a Marker of Word Identification Style and Visual Word Form Area Lateralization
Elizabeth Hirshorn1, Brandon Carlos2, Corrine Durisko3,4, Charles Perfetti3,4, Julie Fiez3,4, Marc Coutanche3,4;1SUNY New Paltz, 2University of Houston, 3University of Pittsburgh, 4Learning Research and Development Center
Background: Skilled visual word identification is a critical component of skilled reading. However, there is more than one underlying mechanism that enables word identification. In an alphabet like English, words can be coded orthographically using different sized visual units (e.g., individual letters, letter clusters, or whole word). By comparison, individual Chinese strokes are not independently meaningful and must be coded more at the whole word-level (i.e., holistic visual processing). Such differences in orthographic coding have been shown to lead to distinct word identification styles in bilingual English readers with different L1 writing systems (Chinese vs. Korean, an alphabet), with Chinese-English bilinguals favoring lexical coding and Korean-English bilinguals favoring sublexical coding. An area in the mid-fusiform gyrus (mFG), the "visual word form area" (VWFA), is associated with visual word identification. The VWFA usually exhibits strong left-lateralization for orthographic stimuli in skilled readers of English, whereas relatively greater bilateral VWFA activation has been observed in Chinese and artificial orthographies that focus on holistic/lexical decoding. Because English has the flexibility to use different types of orthographic coding, the current study examined individual differences in word identification style and VWFA laterality within a native English population. Behavioral Methods & Results: To identify individual differences, a measure of holistic orthographic coding was borrowed from the face processing literature: inversion sensitivity. Participants with high and low visual word inversion sensitivity, but no differences in reading skill, completed a battery of tests of reading sub-skills and an overt word reading test, where words varied along many lexical and sublexical measures (e.g., frequency, bigram frequency, imageability, etc.). Results revealed that greater inversion sensitivity (i.e., greater holistic orthographic coding) was associated with a reading style that relies more on lexical-level processing, and a word representation that relies less on sublexical phonological decoding. fMRI Methods & Results: We used a new multivariate method that used machine learning to assess functional lateralization within the visual word form area (VWFA) and its right hemisphere homologue (rVWFA). We then examined the relationship between individuals’ lateralization results (i.e., differential classification accuracy for alphabetic stimuli in each hemisphere) and their corresponding inversion sensitivity scores. We found a significant relationship between individual differences in neural lateralization and inversion sensitivity, such that individuals with greater inversion sensitivity had greater bilateral VWFA classification accuracy. Conclusions: We conclude that proficient native readers of English exhibit differences in reading style and VWFA lateralization, which has significant implications for reading behavior. Parallels to Chinese-style of reading and a proposed alternative route to skilled reading will be discussed.
Topic Area: Perception: Orthographic and Other Visual Processes