445 research outputs found

    The role of phonology in visual word recognition: evidence from Chinese

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    Posters - Letter/Word Processing V: abstract no. 5024The hypothesis of bidirectional coupling of orthography and phonology predicts that phonology plays a role in visual word recognition, as observed in the effects of feedforward and feedback spelling to sound consistency on lexical decision. However, because orthography and phonology are closely related in alphabetic languages (homophones in alphabetic languages are usually orthographically similar), it is difficult to exclude an influence of orthography on phonological effects in visual word recognition. Chinese languages contain many written homophones that are orthographically dissimilar, allowing a test of the claim that phonological effects can be independent of orthographic similarity. We report a study of visual word recognition in Chinese based on a mega-analysis of lexical decision performance with 500 characters. The results from multiple regression analyses, after controlling for orthographic frequency, stroke number, and radical frequency, showed main effects of feedforward and feedback consistency, as well as interactions between these variables and phonological frequency and number of homophones. Implications of these results for resonance models of visual word recognition are discussed.postprin

    Interactive effects of orthography and semantics in Chinese picture naming

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    Posters - Language Production/Writing: abstract no. 4035Picture-naming performance in English and Dutch is enhanced by presentation of a word that is similar in form to the picture name. However, it is unclear whether facilitation has an orthographic or a phonological locus. We investigated the loci of the facilitation effect in Cantonese Chinese speakers by manipulating—at three SOAs (2100, 0, and 1100 msec)—semantic, orthographic, and phonological similarity. We identified an effect of orthographic facilitation that was independent of and larger than phonological facilitation across all SOAs. Semantic interference was also found at SOAs of 2100 and 0 msec. Critically, an interaction of semantics and orthography was observed at an SOA of 1100 msec. This interaction suggests that independent effects of orthographic facilitation on picture naming are located either at the level of semantic processing or at the lemma level and are not due to the activation of picture name segments at the level of phonological retrieval.postprin

    Semantic, phonological and episodic representations in verbal immediate serial recall

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    Psycholinguistic frameworks provide contemporary accounts of immediate serial recall (e.g., N. Martin & Saffran, 1997; R. C. Martin, Lesch, & Bartha, 1999). These models emphasise the inclusion of semantic/associative and phonological representations in verbal short-term memory but have difficulty explaining how serial order is represented and maintained. Conversely, computational models of immediate serial recall (e.g., Brown, Preece, & Hulme, 2000; Henson, 1998b; Lewandowsky & Farrell, 2008b; Page & Norris, 1998) have typically concentrated on the role of temporary episodic representations on short-term recall but have trouble accounting for the influence of multiple representations on performance. The aim of this research was to combine these two lines of research to form a more integrative approach to immediate serial recall. The intention was to contribute to current understandings of verbal short-term memory by exploring how the binding of semantic/associative, phonological and episodic representations would influence immediate serial recall..

    Verbal monitoring in production and perception : a cognitive neuroscience approach

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    The goal of this dissertation is to investigate the process of verbal monitoring. Specifically, this thesis investigates whether internal and external monitoring proceeds via the same, perception-based process, as proposed by the perceptual loop theory. We compare verbal internal and external monitoring with the use of eye-tracking, fMRI and Parkinson patient data. The data obtained suggest that verbal monitoring is not perception based, and that is a domain general process. We therefore propose the improvement of current monitoring models by describing a domain general monitoring mechanism for internal monitoring and external monitoring, by which conflict is resolved in a process-independent manner

    The source of the associative deficit in aging: the role of attentional resources for processing relational information

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    Previous studies have proposed an associative deficit hypothesis, which attributes part of older adults' deficient episodic memory performance to their difficulty in creating cohesive episodes. According to the ADH, older adults show disproportionate deficits in relational memory (RM) relative to item memory (IM). The disproportionate RM deficit in older adults has been demonstrated with a variety of memory tasks, such as word-word, word-font, and face-name pairs. Despite rich evidence of an age-related RM deficit, the source of this deficit remains unspecified. One of the most widely investigated factors is the reduction in attentional resources in older adults. To investigate the effect of reduced attentional resources on RM performance, previous researchers have imposed a secondary task load on young adults during encoding of memory lists to divide attentional resources into two different tasks. However, none of the existing studies have found a disproportionate RM impairment in young adults under divided attention conditions. The current project investigated whether a reduction in attentional resources for relational processing underlies the memory impairments observed in aging. Using behavioral and functional neuroimaging techniques, I conducted three studies aimed at determining: 1) whether imposing a secondary task load for relational processing makes young adults' memory performance mimic the age-related RM deficit, and 2) whether the effect of reduced attentional resources for relational processing on RM is similar to the effect of aging at the neural level, using functional magnetic resonance imaging (fMRI). The results from the two behavioral studies indicate that a reduction in attentional resources for relational processing in young adults during encoding equates their performance in RM to that of older adults. Furthermore, the results from the fMRI study demonstrate that both aging and reductions in relational attention processing in young adults significantly reduced activity in the brain areas critical for RM formation, namely, the ventrolateral and dorsolateral PFC, superior and inferior parietal regions, and left hippocampus. This converging evidence from behavioral and neuroimaging studies thus documents the first evidence that the reduction in attentional resources for relational processing is the critical factor for the age-related RM deficit

    Early prefrontal activation as a mechanism to prevent forgetting in the context of interference

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    Objective: Recent research has focused on interference resolution deficits as the main cause of short-term memory decreases in aging. To determine whether activation of brain compensatory mechanisms occur during the encoding process in older people. Moreover, two different levels of interference (distraction and interruption) were presented during the maintenance period to examine how they modulate brain activity profiles. Design: A delayed match-to-sample task with two experimental conditions: distraction and interruption. Participants: Twenty-seven young adults from Complutense University of Madrid and 20 healthy older adults from Complutense Elderly University of Madrid. Measurements: Magnetoencephalography scans were recorded during the execution of a working memory interference task. Brain activity sources from younger and older adults during the encoding stage were compared in each condition using minimum norm estimation analyses. Results: The elderly showed enhancement of prefrontal activity during early latencies of the encoding process in both conditions. In the distraction condition, enhanced activity was located in left ventrolateral prefrontal regions, whereas in the interruption condition, enhanced activity was observed in the right ventral prefrontal areas and anterior cingulate cortex. Conclusion: Increased recruitment of prefrontal regions in the elderly might be related to the processing depth of information, encoding of new information and semantic associations that are successfully recalled, and with interference resolution and preparatory control when the level of interference becomes higher. These prefrontal modulations during early latencies might reflect a higher top-down control of the encoding process in normal aging to prevent forgetting

    Altered brain activation during memory retrieval precedes and predicts conversion to psychosis in individuals at clinical high risk

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    Memory deficits are a hallmark of psychotic disorders such as schizophrenia. However, whether the neural dysfunction underlying these deficits is present before the onset of illness and potentially predicts conversion to psychosis is unclear. In this study, we investigated brain functional alterations during memory processing in a sample of 155 individuals at clinical high risk (including 18 subjects who later converted to full psychosis) and 108 healthy controls drawn from the second phase of the North American Prodrome Longitudinal Study (NAPLS-2). All participants underwent functional magnetic resonance imaging with a paired-associate memory paradigm at the point of recruitment and were clinically followed up for approximately 2 years. We found that at baseline, subjects at high risk showed significantly higher activation during memory retrieval in the prefrontal, parietal, and bilateral temporal cortices (PFWE < .035). This effect was more pronounced in converters than nonconverters and was particularly manifested in unmedicated subjects (P < .001). The hyperactivation was significantly correlated with retrieval reaction time during scan in converters (P = .009) but not in nonconverters and controls, suggesting an exaggerated retrieval effort. These findings suggest that hyperactivation during memory retrieval may mark processes associated with conversion to psychosis, and such measures have potential as biomarkers for psychosis prediction
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