Search results for " Visual"
showing 10 items of 1041 documents
Object switching within working memory is reflected in the human event-related brain potential
2008
In two experiments applying a memory updating task subjects are asked to perform several arithmetic operations on stored numbers. From a trial-to-trial perspective these operations could be either performed on a previously processed item or on a new item which requires an object switch in working memory. Object switching results in prolonged operation times; these operation time costs reflect the switch of the focus of attention to the relevant information. Event-related brain potentials obtained in object switch trials show an increased P3a around 300 ms and a late, central negative component between 400 ms and 500 ms. The data suggest that the P3a may reflect the unhitching of the focus o…
Effect of Practice, Mapping, Stimulus and Size on String Matching
1987
The same-different discrepancy on a matching task on which the subject had to determine the number of common elements (physically identical and appearing in the same position) between two strings of size 1 to 4 was investigated. Manipulated also were the type of presentation (fixed or varied sets), amount of practice (four blocks), and type of stimulus (letters, words). Reaction times for pure positive responses (all same at each level) were faster than negative responses (all different), confirming the usual discrepancy shown in previous studies. The discrepancy was smaller for well-learned sets (fixed sets) and for words, indicating the development of a comparison process based on global…
LOW-RANK APPROXIMATION BASED NON-NEGATIVE MULTI-WAY ARRAY DECOMPOSITION ON EVENT-RELATED POTENTIALS
2014
Non-negative tensor factorization (NTF) has been successfully applied to analyze event-related potentials (ERPs), and shown superiority in terms of capturing multi-domain features. However, the time-frequency representation of ERPs by higher-order tensors are usually large-scale, which prevents the popularity of most tensor factorization algorithms. To overcome this issue, we introduce a non-negative canonical polyadic decomposition (NCPD) based on low-rank approximation (LRA) and hierarchical alternating least square (HALS) techniques. We applied NCPD (LRAHALS and benchmark HALS) and CPD to extract multi-domain features of a visual ERP. The features and components extracted by LRAHALS NCP…
Multi-domain feature extraction for small event-related potentials through nonnegative multi-way array decomposition from low dense array EEG
2013
Non-negative Canonical Polyadic decomposition (NCPD) and non-negative Tucker decomposition (NTD) were compared for extracting the multi-domain feature of visual mismatch negativity (vMMN), a small event-related potential (ERP), for the cognitive research. Since signal-to-noise ratio in vMMN is low, NTD outperformed NCPD. Moreover, we proposed an approach to select the multi-domain feature of an ERP among all extracted features and discussed determination of numbers of extracted components in NCPD and NTD regarding the ERP context.
Exploring the switching of the focus of attention within working memory: A combined event-related potential and behavioral study.
2018
Abstract Working memory enables humans to maintain selected information for cognitive processes and ensures instant access to the memorized contents. Theories suggest that switching the focus of attention between items within working memory realizes the access. This is reflected in object-switching costs in response times when the item for the task processing is to be changed. Another correlate of attentional allocation in working memory is the P3a-component of the human event-related potential. The aim of this study was to demonstrate that switching of attention within working memory is a separable processing step. Participants completed a cued memory-updating task in which they were instr…
Holistic face processing is induced by shape and texture.
2013
There is increasing evidence that shape and texture are integral parts of face identity. However, it is less clear whether face-specific processing mechanisms are triggered by face shape alone, or if texture might play an important role. We address this question by studying mechanisms involved in holistic face processing. Face stimuli were either full-color pictures of real faces (shape and texture) or line drawings of the same faces (shape without texture). In a change detection task subjects judged whether eyes and eyebrows in two otherwise identical, sequentially presented faces were different in size or not. Afterwards, subjects had to identify the just presented face among two distrac…
Effects of masked repetition priming and orthographic neighborhood in visual recognition of words.
1996
Summay.-The role of orthographic neighborhood (neighborhood size and neighborhood Erequency) in visual-word recognition was analyzed using the masked repetition-priming paradigm. Specifically, we varied stimulus-onset asynchrony (33, 50, and 67 msec.) and type of prime (identical, unrelated, unprimed) in a lexical-decision task. Analyses show additive effects of repetition and stimulus-onset asynchrony. Further, the unrelated condition overestimated the repetition effects relative ro an unprimed condition. Fachtatory effects of neighborhood size and inhibitory effects of neighborhood frequency were also found. The results are interpreted in terms of current models of visual-word recognition…
Implicit memory functioning in schizophrenia: Explaining inconsistent findings of word stem completion tasks
2014
The definitive implicit memory profile of schizophrenia is yet to be clarified. Methodological differences between studies could be the reason for the inconsistent findings reported. In this study, we have examined implicit memory functioning using a word stem completion task. In addition, we have addressed methodological issues related with lexical and perceptual stimuli characteristics, and with the strategy used to calculate priming scores. Our data show similar performance values in schizophrenic patients and healthy controls. Furthermore, we have not detected significant differences in priming between the two groups, even when this parameter was calculated using three different procedu…
Perceptual priming in schizophrenia evaluated by word fragment and word stem completion
2011
Implicit memory seems to be preserved in schizophrenia as a whole, but dissociations between conceptual and perceptual tasks and between accuracy and reaction time measures have appeared. The present research has revealed some methodological limitations in many studies to date that are focused on the study of perceptual implicit memory in schizophrenic patients using accuracy measures. The review of these studies revealed that limitations are related to an inadequate definition of performance and priming measures, a lack of control over the characteristics of the stimuli, and the absence of information on the experimental procedures used in data collection. Moreover, the task used in these …
The development of facial emotion recognition: The role of configural information
2007
International audience; The development of children's ability to recognize facial emotions and the role of configural information in this development were investigated. In the study, 100 5-, 7-, 9-, and 11-year-olds and 26 adults needed to recognize the emotion displayed by upright and upside-down faces. The same participants needed to recognize the emotion displayed by the top half of an upright or upside-down face that was or was not aligned with a bottom half that displayed another emotion. The results showed that the ability to recognize facial emotion develops with age, with a developmental course that depends on the emotion to be recognized. Moreover, children at all ages and adults e…