The Experts below are selected from a list of 59961 Experts worldwide ranked by ideXlab platform
Yi Jiang - One of the best experts on this subject based on the ideXlab platform.
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anodal occipital transcranial direct current stimulation enhances perceived visual Size illusions
Journal of Cognitive Neuroscience, 2021Co-Authors: Anqi Wang, Lihong Chen, Yi JiangAbstract:Human early visual cortex has long been suggested to play a crucial role in context-dependent visual Size Perception through either lateral interaction or feedback projections from higher to lower visual areas. We investigated the causal contribution of early visual cortex to context-dependent visual Size Perception using the technique of transcranial direct current stimulation and two well-known Size illusions (i.e., the Ebbinghaus and Ponzo illusions) and further elucidated the underlying mechanism that mediates the effect of transcranial direct current stimulation over early visual cortex. The results showed that the magnitudes of both Size illusions were significantly increased by anodal stimulation relative to sham stimulation but left unaltered by cathodal stimulation. Moreover, the anodal effect persisted even when the central target and surrounding inducers of the Ebbinghaus configuration were presented to different eyes, with the effect lasting no more than 15 min. These findings provide compelling evidence that anodal occipital stimulation enhances the perceived visual Size illusions, which is possibly mediated by weakening the suppressive function of the feedback connections from higher to lower visual areas. Moreover, the current study provides further support for the causal role of early visual cortex in the neural processing of context-dependent visual Size Perception.
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anodal occipital transcranial direct current stimulation enhances perceived visual Size illusions
Journal of Cognitive Neuroscience, 2021Co-Authors: Anqi Wang, Lihong Chen, Yi JiangAbstract:Human early visual cortex has long been suggested to play a crucial role in context-dependent visual Size Perception through either lateral interaction or feedback projections from higher to lower ...
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My own face looks larger than yours: A self-induced illusory Size Perception
'Elsevier BV', 2021Co-Authors: Ying Zhang, Li Wang, Yi JiangAbstract:Size Perception of visual objects is highly context dependent. Here we report a novel perceptual Size illusion that the self-face, being a unique and distinctive self-referential stimulus, can enlarge its perceived Size. By using a Size discrimination paradigm, we found that the self-face was perceived as significantly larger than the other-face of the same Size. This Size overestimation effect was not due to the familiarity of the self-face, since it could be still observed when the self-face was directly compared with a famous face. More crucially, such illusion effect could be extended to a new cartoon face that was transiently associated with one’s own face and could also exert further contextual influences on visual Size Perception of other objects. These findings together highlight the role of self-awareness in visual Size Perception and point to a special mechanism of Size Perception tuned to self-referential information.
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subconscious processing reveals dissociable contextual modulations of visual Size Perception
Cognition, 2018Co-Authors: Lihong Chen, Congying Qiao, Ying Wang, Yi JiangAbstract:Visual Size Perception is highly context-dependent. In a series of experiments reported here, we demonstrated that the contextual modulation of visual Size processing could occur independent of conscious awareness. Specifically, the Ebbinghaus illusion, which is mediated by lateral connections within the early visual processing stream, persisted even when the surrounding inducers were rendered invisible. Moreover, when the central target was initially interocularly suppressed, the identical target emerged from suppression faster when surrounded by small relative to large inducers, with the suppression time difference well predicted by the strength of the illusion. By contrast, there were no such subconscious contextual modulation effects associated with the Ponzo illusion, which largely relies on feedback projections to the early visual cortices. These results indicate that contextual information can modulate visual Size Perception without conscious awareness, and the dissociated modulation effects further suggest that subconscious contextual modulation takes place in the early visual processing stream and is largely independent of high-level feedback influences.
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low spatial frequency bias in context dependent visual Size Perception
Journal of Vision, 2018Co-Authors: Lihong Chen, Congying Qiao, Yi JiangAbstract:Spatial frequency (SF) information is essential for visual Perception. By combining a sensitization procedure and the Ebbinghaus illusion, we investigated the effect of SF bias in context-dependent visual Size Perception. During the sensitization phase, participants were repeatedly presented with low- or high-pass filtered faces or gratings and were asked to discriminate the gender or the orientation of them, respectively. Immediately following the sensitization phase, the Ebbinghaus illusion strength was measured. The results showed that the illusion strength was significantly larger when the prior sensitized images were low-pass filtered relative to when they were high-pass filtered. Moreover, this SF bias was independent of low-level features and the specific content of the filtered images. Our findings extend the understanding of SF bias induced by sensitization in visual domain, and suggest that the processing of context-dependent visual Size information is likely to involve magnocellular projections from subcortical areas via low SF channel.
H S Kruger - One of the best experts on this subject based on the ideXlab platform.
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level of agreement between objectively determined body composition and perceived body image in 6 to 8 year old south african children the body composition isotope technique study
PLOS ONE, 2020Co-Authors: Lynn T Moengmahlangu, M A Monyeki, John J Reilly, Zandile Mchiza, Thabisile Moleah, Cornelia U Loechl, H S KrugerAbstract:To assess the level of agreement between body Size self-Perception and actual body Size determined by body mass index (BMI) z-score and body fatness measured by the deuterium dilution method (DDM) in South African children aged 6-8 years. A cross-sectional sample of 202 children (83 boys and 119 girls) aged 6-8 years from the Body Composition-Isotope Technique study (BC-IT) was taken. Subjective measures of body image (silhouettes) were compared with the objective measures of BMI z-score and body fatness measured by the DDM. The World Health Organization BMI z-scores were used to classify the children as underweight, normal, overweight, or obese. DDM-measured fatness was classified based on the McCarthy centile curves set at 2nd, 85th and 95th in conjunction with fatness cut-off points of 25% in boys and 30% in girls. Data were analyzed using SPSS v26. Of 202 children, 32.2%, 55.1%, 8.8%, and 2.4% perceived their body Size as underweight, normal, overweight, and obese, respectively. Based on BMI z-score, 18.8%, 72.8%, 6.9%, and 1.5% were classified as underweight, normal, overweight, and obese, respectively. Body fatness measurement showed that 2.5%, 48.0%, 21.8%, and 29.7% were underweight, normal weight, overweight, and obese, respectively. The application of silhouettes and BMI z-scores resulted in either overestimation or underestimation of own body Size. Overall, the levels of agreements (kappa, κ) between body Size Perception, body fatness, and BMI for age respectively, were small (κ = 0.083, p = 0.053 and κ = 0.154, p<0.001). Level of agreement between body Size Perception, body fatness, and BMI z-score was poor. The use of silhouettes made children either overestimate their own body Size while being underweight or underestimate their own body Size while being overweight or obese. Given the potential health implications associated with misclassification of body Size during childhood, correct self-assessment of body Size is important, and may be key to the adoption of weight control strategies directed at curbing the escalating obesity epidemic in the country. Scalable measures to allow for more accurate self-assessment are urgently needed-one approach is behavior change communication at all levels.
Anqi Wang - One of the best experts on this subject based on the ideXlab platform.
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anodal occipital transcranial direct current stimulation enhances perceived visual Size illusions
Journal of Cognitive Neuroscience, 2021Co-Authors: Anqi Wang, Lihong Chen, Yi JiangAbstract:Human early visual cortex has long been suggested to play a crucial role in context-dependent visual Size Perception through either lateral interaction or feedback projections from higher to lower visual areas. We investigated the causal contribution of early visual cortex to context-dependent visual Size Perception using the technique of transcranial direct current stimulation and two well-known Size illusions (i.e., the Ebbinghaus and Ponzo illusions) and further elucidated the underlying mechanism that mediates the effect of transcranial direct current stimulation over early visual cortex. The results showed that the magnitudes of both Size illusions were significantly increased by anodal stimulation relative to sham stimulation but left unaltered by cathodal stimulation. Moreover, the anodal effect persisted even when the central target and surrounding inducers of the Ebbinghaus configuration were presented to different eyes, with the effect lasting no more than 15 min. These findings provide compelling evidence that anodal occipital stimulation enhances the perceived visual Size illusions, which is possibly mediated by weakening the suppressive function of the feedback connections from higher to lower visual areas. Moreover, the current study provides further support for the causal role of early visual cortex in the neural processing of context-dependent visual Size Perception.
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anodal occipital transcranial direct current stimulation enhances perceived visual Size illusions
Journal of Cognitive Neuroscience, 2021Co-Authors: Anqi Wang, Lihong Chen, Yi JiangAbstract:Human early visual cortex has long been suggested to play a crucial role in context-dependent visual Size Perception through either lateral interaction or feedback projections from higher to lower ...
Samuel D Schwarzkopf - One of the best experts on this subject based on the ideXlab platform.
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cortical idiosyncrasies predict the Perception of object Size
Nature Communications, 2016Co-Authors: Christina Moutsiana, Benjamin De Haas, Andriani Papageorgiou, Jelle A Van Dijk, Annika Balraj, John A Greenwood, Samuel D SchwarzkopfAbstract:Perception is subjective. Even basic judgments, like those of visual object Size, vary substantially between observers and also across the visual field within the same observer. The way in which the visual system determines the Size of objects remains unclear, however. We hypotheSize that object Size is inferred from neuronal population activity in V1 and predict that idiosyncrasies in cortical functional architecture should therefore explain individual differences in Size judgments. Here we show results from novel behavioural methods and functional magnetic resonance imaging (fMRI) demonstrating that biases in Size Perception are correlated with the spatial tuning of neuronal populations in healthy volunteers. To explain this relationship, we formulate a population read-out model that directly links the spatial distribution of V1 representations to our perceptual experience of visual Size. Taken together, our results suggest that the individual Perception of simple stimuli is warped by idiosyncrasies in visual cortical organization.
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cortical idiosyncrasies predict the Perception of object Size
bioRxiv, 2016Co-Authors: Christina Moutsiana, Benjamin De Haas, Andriani Papageorgiou, Jelle A Van Dijk, Annika Balraj, John A Greenwood, Samuel D SchwarzkopfAbstract:Perception is subjective. Even basic judgments, like those of visual object Size, vary substantially between observers and also across the visual field within the same observer. The way in which the visual system determines the Size of objects remains unclear, however. We hypotheSize that object Size is inferred from neuronal population activity in V1 and predict that idiosyncrasies in cortical functional architecture should therefore explain individual differences in Size judgments. Indeed, using novel behavioral methods and functional magnetic resonance imaging (fMRI) we demonstrate that biases in Size Perception are correlated with the spatial tuning of neuronal populations in healthy volunteers. To explain this relationship, we formulate a population read-out model that directly links the spatial distribution of V1 representations to our perceptual experience of visual Size. Altogether, we suggest that the individual Perception of simple stimuli is warped by idiosyncrasies in visual cortical organization.
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subjective Size Perception depends on central visual cortical magnification in human v1
PLOS ONE, 2013Co-Authors: Samuel D Schwarzkopf, Geraint ReesAbstract:In the Ebbinghaus illusion, the context surrounding an object modulates its subjectively perceived Size. Previous work implicates human primary visual cortex (V1) as the neural substrate mediating this contextual effect. Here we studied in healthy adult humans how two different types of context (large or small inducers) in this illusion affected Size Perception by comparing each to a reference stimulus without any context. We found that individual differences in the magnitudes of the illusion produced by either type of context were correlated with V1 area defined through retinotopic mapping using functional MRI. However, participants' objective ability to discriminate the Size of objects presented in isolation was unrelated to illusion strength and did not correlate with V1 area. Control analyses showed no correlations between behavioral measures and the overall V1 area estimated probabilistically on the basis of neuroanatomy alone. Therefore, subjective Size Perception correlated with variability in central cortical magnification rather than the anatomical extent of primary visual cortex. We propose that such changes in subjective Perception of Size are mediated by mechanisms that scale with the extent to which an individual's V1 selectively represents the central visual field.
Lihong Chen - One of the best experts on this subject based on the ideXlab platform.
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anodal occipital transcranial direct current stimulation enhances perceived visual Size illusions
Journal of Cognitive Neuroscience, 2021Co-Authors: Anqi Wang, Lihong Chen, Yi JiangAbstract:Human early visual cortex has long been suggested to play a crucial role in context-dependent visual Size Perception through either lateral interaction or feedback projections from higher to lower visual areas. We investigated the causal contribution of early visual cortex to context-dependent visual Size Perception using the technique of transcranial direct current stimulation and two well-known Size illusions (i.e., the Ebbinghaus and Ponzo illusions) and further elucidated the underlying mechanism that mediates the effect of transcranial direct current stimulation over early visual cortex. The results showed that the magnitudes of both Size illusions were significantly increased by anodal stimulation relative to sham stimulation but left unaltered by cathodal stimulation. Moreover, the anodal effect persisted even when the central target and surrounding inducers of the Ebbinghaus configuration were presented to different eyes, with the effect lasting no more than 15 min. These findings provide compelling evidence that anodal occipital stimulation enhances the perceived visual Size illusions, which is possibly mediated by weakening the suppressive function of the feedback connections from higher to lower visual areas. Moreover, the current study provides further support for the causal role of early visual cortex in the neural processing of context-dependent visual Size Perception.
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anodal occipital transcranial direct current stimulation enhances perceived visual Size illusions
Journal of Cognitive Neuroscience, 2021Co-Authors: Anqi Wang, Lihong Chen, Yi JiangAbstract:Human early visual cortex has long been suggested to play a crucial role in context-dependent visual Size Perception through either lateral interaction or feedback projections from higher to lower ...
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subconscious processing reveals dissociable contextual modulations of visual Size Perception
Cognition, 2018Co-Authors: Lihong Chen, Congying Qiao, Ying Wang, Yi JiangAbstract:Visual Size Perception is highly context-dependent. In a series of experiments reported here, we demonstrated that the contextual modulation of visual Size processing could occur independent of conscious awareness. Specifically, the Ebbinghaus illusion, which is mediated by lateral connections within the early visual processing stream, persisted even when the surrounding inducers were rendered invisible. Moreover, when the central target was initially interocularly suppressed, the identical target emerged from suppression faster when surrounded by small relative to large inducers, with the suppression time difference well predicted by the strength of the illusion. By contrast, there were no such subconscious contextual modulation effects associated with the Ponzo illusion, which largely relies on feedback projections to the early visual cortices. These results indicate that contextual information can modulate visual Size Perception without conscious awareness, and the dissociated modulation effects further suggest that subconscious contextual modulation takes place in the early visual processing stream and is largely independent of high-level feedback influences.
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low spatial frequency bias in context dependent visual Size Perception
Journal of Vision, 2018Co-Authors: Lihong Chen, Congying Qiao, Yi JiangAbstract:Spatial frequency (SF) information is essential for visual Perception. By combining a sensitization procedure and the Ebbinghaus illusion, we investigated the effect of SF bias in context-dependent visual Size Perception. During the sensitization phase, participants were repeatedly presented with low- or high-pass filtered faces or gratings and were asked to discriminate the gender or the orientation of them, respectively. Immediately following the sensitization phase, the Ebbinghaus illusion strength was measured. The results showed that the illusion strength was significantly larger when the prior sensitized images were low-pass filtered relative to when they were high-pass filtered. Moreover, this SF bias was independent of low-level features and the specific content of the filtered images. Our findings extend the understanding of SF bias induced by sensitization in visual domain, and suggest that the processing of context-dependent visual Size information is likely to involve magnocellular projections from subcortical areas via low SF channel.