The N1 effect is an electrophysiological marker of visual specialization for print. The phonological mapping hypothesis (Maurer & McCandliss, 2007) posits that the left‐lateralized effect reflects grapheme‐phoneme integration. In this event‐related potential study, first (age = 7.06 years, N = 32) and third‐grade readers (age = 9.29 years, N = 28) were presented with pairs of pseudowords and Armenian character strings in a novel implicit same‐different paradigm. To test the phonological mapping hypothesis, stimuli were presented in visual‐only and audiovisual conditions. The results demonstrated that tuning for print already emerges in first grade. Moreover, the parallel presentation of auditory stimuli enhanced the N1 effect suggesting a role of orthographic‐phonological mapping in the development of specialization for print.
Previous research recognized that humans could extract statistical regularities of the environment to automatically predict upcoming events. However, it has remained unexplored how the brain encodes the distribution of statistical regularities if it continuously changes. To investigate this question, we devised an fMRI paradigm where participants (N = 32) completed a visual four-choice reaction time (RT) task consisting of statistical regularities. Two types of blocks involving the same perceptual elements alternated with one another throughout the task: While the distribution of statistical regularities was predictable in one block type, it was unpredictable in the other. Participants were unaware of the presence of statistical regularities and of their changing distribution across the subsequent task blocks. Based on the RT results, although statistical regularities were processed similarly in both the predictable and unpredictable blocks, participants acquired less statistical knowledge in the unpredictable as compared with the predictable blocks. Whole-brain random-effects analyses showed increased activity in the early visual cortex and decreased activity in the precuneus for the predictable as compared with the unpredictable blocks. Therefore, the actual predictability of statistical regularities is likely to be represented already at the early stages of visual cortical processing. However, decreased precuneus activity suggests that these representations are imperfectly updated to track the multiple shifts in predictability throughout the task. The results also highlight that the processing of statistical regularities in a changing environment could be habitual.
A siketek olvasási folyamatainak vizsgálatából származó eredmények számos információval szolgálnak a tipikusan működő olvasási rendszer természetéről. A siketség következtében a fonológiai feldolgozás akadályozott, így tesztelhetővé válik a fonológiai rendszer szerepe az olvasásban. Jelen tanulmányban áttekintjük a siketekkel végzett olvasási vizsgálatokból származó főbb eredményeket, ebben külön kitérve a fonológiai, ortográfiai és szemantikai rendszer sajátosságaira, valamint ezeknek a rendszereknek az interakcióira. Végül bemutatjuk, hogy az ismert kutatási eredmények milyen elméleti implikációval bírnak a tipikus olvasás leírására szolgáló kognitív modellek számára.
Automatic visual word recognition requires not only well-established phonological and orthographic representations but also efficient audio-visual integration of these representations. One possibility is that in developmental dyslexia, inefficient orthographic processing might underlie poor reading. Alternatively, reading deficit could be due to inefficient phonological processing or inefficient integration of orthographic and phonological information. In this event-related potential study, participants with dyslexia (N = 25) and control readers (N = 27) were presented with pairs of words and pseudowords in an implicit same-different task. The reference-target pairs could be identical, or different in the identity or the position of the letters. To test the orthographic-phonological processing, target stimuli were presented in visual-only and audiovisual conditions. Participants with and without dyslexia processed the reference stimuli similarly; however, group differences emerged in the processing of target stimuli, especially in the audiovisual condition where control readers showed greater N1 responses for words than for pseudowords, but readers with dyslexia did not show such difference. Moreover, after 300 ms lexicality effect exhibited a more focused frontal topographic distribution in readers with dyslexia. Our results suggest that in developmental dyslexia, phonological processing and audiovisual processing deficits are more pronounced than orthographic processing deficits.
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