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Orthographic processing

Sunday, October 02nd,   2011 [18:00 - 20:00]

PS_3.082 - Related word primes alone do not inhibit target RTs in a masked prime LDT

Zimmerman, R. , Geller, J. & Gomez, P.

DePaul University

Interactive-Activation based models of lexical access predict that a word prime inhibits processing of an orthographically related target item in the lexical decision task (LDT). Although results supporting this hypothesis have been found, many other studies have failed to find the predicted inhibitory effects of related word primes. In Experiment 1 (n=124), we presented subjects with a standard LDT, and we failed to find inhibition with related word primes. In Experiment 2 (n=44), we manipulated the duration of several primes during the LDT to draw attention to the temporal location of the prime. Doing so increased the magnitude of other predicted effects, and yielded the expected inhibition only for related low frequency word primes. In Experiment 3 (n=23) we used a LDT while recording pupil dilation along with RT's. Again, while we obtained the expected frequency effects, neither RT nor pupil dilation indicated inhibition or increased arousal/processing of related word primes. Our results emphasize the difficulty in obtaining inhibition of related word primes.

PS_3.083 - The neural substrates underlying reading and its age-related changes in Japanese children: A functional magnetic resonance imaging study

Uchiyama, H. 1, 2, 3 , Seki, A. 1, 2, 3 , Tanaka, D. 1, 2, 3 & Koeda, T. 1, 2, 3

1 Department of Education, Faculty of Regional Sciences, Tottori University, Tottori, Japan
2 Department of Clinical Research, Tottori Medical Center, National Hospital Organization
3 Japan Science and Technology Agency (JST)/Research Institute of Science and Technology for Society (RISTEX), Tokyo, Japan

Studies have shown that the fusiform gyrus (FG), inferior parietal lobes (IPL), and inferior frontal gyrus (IFG) play important roles in the reading of alphabetic languages. Functional MRI (fMRI) studies on alphabetic languages show that the activation of the FG is associated with fluent-word recognition in skilled readers. Although FG has been identified to be crucial for the reading of Japanese logographic kanji characters, but not of phonographic kana characters, it is activated even for kana characters when their visual familiarity is high. This indicates the dynamic changes in reading systems during the development of skills required for reading Japanese. To delineate the age-related changes in the reading system, we conducted an fMRI with 48 school-aged children. Subjects performed a picture-word matching task: they judged whether the given pictures matched the written words and nonwords. The left FG and left IPL were activated more strongly when the students were presented with familiar words than with letter strings (nonwords). This activation in the IPL and left IFG decreased with age, but there was no such decrease in the FG region. This age-related diminishing activation might indicate a change in the reading skill, from letter-by-letter decoding to fluent-word recognition.

PS_3.084 - Imaging orthographic learning: Differential contributions of the fusiform gyrus and hippocampus

Schubert, T. & Rapp, B.

Department of Cognitive Science. Johns Hopkins University. Baltimore, USA.

Research has identified the role of the left mid-fusiform gyrus in reading (Cohen et al., 2002) and spelling (Rapp & Lipka, 2011). Furthermore, this region -often referred to as the VWFA (Visual Word Form Area) has been implicated in acquisition of literacy (Dehaene, et al. 2010) and also shows increased processing efficiency with increasing word frequency and with repeated presentations of written words (Pugh et al., 2008). The current study examined the involvement of the VWFA and the hippocampus in the real-time learning of orthographic representations by normal adults. During scanning, participants learned mappings between auditory pseudowords and orthographic forms. Whole-brain analysis revealed that the orthographic learning recruited the left mid-fusiform gyrus, left inferior gyrus, and left supramarginal gyrus. Learning trials were categorized both by presentation number (Pugh et al., 2008) and memory strength (Law et al., 2005) to investigate the time course of learning. Results revealed that activation in the functionally-defined VWFA decreased as both memory strength and number of repetitions increased. Conversely, activation in the bilateral hippocampus increased as a function of memory strength. These results provide novel evidence of the distinctive roles played by the VWFA and hippocampus in acquisition of orthographic representations.

PS_3.085 - Location-invariant visual word recognition in a hierarchical generative model

Di Bono, M. G. & Zorzi, M.

Department of General Psychology, University of Padova

Relative-position and transposition priming effects in visual word recognition have inspired alternative proposals about the nature of orthographic coding. The Open-Bigram model assumes that the relative position of a letter within a word is coded through its constituent ordered letter pairs. Alternatively, the Overlap model assumes that each letter is coded by a gaussian distribution of activation across the ordinal positions in a word. We asked what type of intermediate coding would emerge in a neural network learning location-invariant representations of written words. We trained a “deep” network with many layers on an artificial dataset of 120 words (trigrams) presented at five possible locations. The network learned a hierarchical generative model of the sensory input (unsupervised learning). We analysed the internal representations across layers as a function of input stimulus type (words, letters, bigrams). Word selectivity and location invariance increased as a function of layer depth. The activation pattern of each word was highly correlated with those of the first constituent letter and the constituent open bigram (i.e., the first and the last constituent letters). These results, though preliminary, suggest that bigram coding plays an important role in word recognition.

PS_3.086 - When less is more: Feedback, priming, and the pseudoword superiority effect

Massol, S. 1, 2 , Midgley, K. 2, 3 , Holcomb, P. J. 3 & Grainger, J. 2, 4

2 Aix-Marseille University
3 Tufts University
4 Centre National de la Recherche Scientifique

The present study combined masked priming with electrophysiological recordings to investigate orthographic priming effects with nonword targets. Targets were pronounceable nonwords (e.g.,STRENG) or consonant strings (e.g.,STRBNG), that both differed from a real world by a single letter substitution (STRONG). Targets were preceded by related primes that could be the same as the target (e.g., streng-STRENG, strbng-STRBNG) or the real word neighbor of the target (e.g., strong-STRENG, strong-STRBNG). Independently of priming, pronounceable nonwords were associated with larger negativities than consonant strings, starting at 290 ms post-target onset. Overall, priming effects were stronger and longer-lasting with pronounceable nonwords than consonant strings. However, consonant string targets showed an early effect of word neighbor priming in the absence of an effect of repetition priming, whereas pronounceable nonwords showed both repetition and word neighbor priming effects in the same time window. This pattern of priming effects is taken as evidence for feedback from whole-word orthographic representations activated by the prime stimulus that influences bottom-up processing of prelexical representations during target processing.

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