Visual word activation in pure alexia

Bub, DN

doi:10.1093/neucas/1.2.139-e

Cited by 16 publications

(22 citation statements)

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“…In the masked lexical decision task, however, it seems plausible that subjects may have made accurate positive responses on many trials without being aware of the target word's identity, using instead a sense of familiarity, as suggested by the distributed memory model. Consistent with this suggestion, Bub and Arguin (1995) reported that a patient with pure alexia, who showed the characteristic pattern of laborious letter-by-letter reading when asked to identify words, achieved above-chance lexical decision accuracy when the exposure duration of targets was well below that normally required for the patient to report the word's identity. Therefore, the masked lexical decision task may have been particularly well suited for models-such as the distributed memory model-that rely on a single evaluative dimension for discriminating between words and nonwords.…”

Section: Methodsmentioning

confidence: 66%

More than meets the eye: Context effects in word identification

Masson

Borowsky

1998

Mem Cogn

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The influence of semantic context on word identification was examined using masked target displays, Related prime words enhanced a signal detection measure of sensitivity in making lexical decisions and in determining whether a probe word matched the target word. When line drawings were used as primes, a similar benefit was obtained with the probe task. Although these results suggest that contextual information affects perceptual encoding, this conclusion is questioned on the grounds that sensitivity in these tasks may be determined by independent contributions of perceptual and contextual information. The plausibility of this view is supported by a simulation of the experiments using a connectionist model in which perceptual and semantic information make independent contributions to word identification. The model also predicts results with two other analytic methods that have been used to argue for priming effects on perceptual encoding.The identification of objects or events in the environment, including written and spoken language, benefits from the availability of conceptual1y relevant information provided by the context in which an object or event occurs. For example, the identification of visual1y presented individualletters is enhanced when they are placed in the context ofa familiar word (see, e.g., McClel1and& Rumelhart,

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Section: Methodsmentioning

confidence: 66%

More than meets the eye: Context effects in word identification

Masson

Borowsky

1998

Mem Cogn

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“…The performance of alexic patients in those tasks do not result from letter-byletter reading, a strategy which must even be carefully prevented to allow implicit reading to emerge (Coslett, Saffran EM, Greenbaum S, & Schwartz, 1993). Accordingly, whenever word length was studied, no influence of this parameter on lexical decision was found (Bub & Arguin, 1995;Coslett & Saffran, 1989). Similarly, briefly displayed masked words, although they escaped explicit report, primed subsequent targets in an alexic patient.…”

Section: Residual Parallel Letter Perception?mentioning

confidence: 89%

The pathophysiology of letter-by-letter reading

et al. 2004

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Pure alexia is a frequent and incapacitating consequence of left occipitotemporal lesions. It is thought to result from the disruption or the disconnection of the visual word form area (VWFA), a region reproducibly located within the left occipito-temporal sulcus, and encoding the abstract identity of strings of visual letters. Alexic patients often retain effective single letter recognition abilities, and develop an effortful letter-by-letter reading strategy which is the basis of most rehabilitation techniques. We study a patient who developed letter-by-letter reading following the surgical removal of left occipito-temporal regions. Using anatomical and functional MRI in the patient and in normal controls, we show that alexia resulted from the deafferentation of left fusiform cortex, and we analyze the network of brain regions subtending letter-by-letter reading. We propose that during letter-by-letter reading (1) letters are identified in the intact right-hemispheric visual system, with a central role for the region symetrical to the VWFA; (2) letters are serially transferred to the left hemisphere through the intact segment of the corpus callosum; (3) word identity is eventually recovered in the left hemisphere through verbal working memory processes involving inferior frontal and supramarginal cortex.

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“…In particular, ERPs provide temporally and functionally specific measures of processing that may help circumvent limitations of the lexical decision and naming tasks that have been widely used to investigate language comprehension asymmetries. For instance, research with aphasic individuals suggests that the processes that support lexical decision and those that allow semantic classification are nonidentical (Bub & Arguin, 1995). Moreover, the speed and accuracy of lexical decision and naming often underestimate semantic processing capacity in the isolated right hemisphere of commisurotomy patients (Zaidel, 1990).…”

Section: Event-related Potentials and Cognitive Processingmentioning

confidence: 99%

Right Hemisphere Sensitivity to Word- and Sentence-Level Context: Evidence From Event-Related Brain Potentials.

Coulson¹,

Federmeier²,

Petten³

et al. 2005

Journal of Experimental Psychology: Learning, Memory, and Cogni

152

141

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Researchers using lateralized stimuli have suggested that the left hemisphere is sensitive to sentence-level context, whereas the right hemisphere (RH) primarily processes word-level meaning. The authors investigated this message-blind RH model by measuring associative priming with event-related brain potentials (ERPs). For word pairs in isolation, associated words elicited more positive ERPs than unassociated words with similar magnitudes and onset latencies in both visual fields. Embedded in sentences, these same pairs showed large sentential context effects in both fields. Small effects of association were observed, confined to incongruous sentences after right visual hemifield presentation but present for both congruous and incongruous sentences after left visual hemifield presentation. Results do not support the message-blind RH model but do suggest hemispheric asymmetries in the use of word and sentence context during real-time processing.

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Visual word activation in pure alexia

Cited by 16 publications

References 0 publications

More than meets the eye: Context effects in word identification

More than meets the eye: Context effects in word identification

The pathophysiology of letter-by-letter reading

Right Hemisphere Sensitivity to Word- and Sentence-Level Context: Evidence From Event-Related Brain Potentials.

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