The Experts below are selected from a list of 1020 Experts worldwide ranked by ideXlab platform
Irene Sperandio - One of the best experts on this subject based on the ideXlab platform.
-
size constancy is preserved but Afterimages are prolonged in typical individuals with higher degrees of self reported autistic traits
Journal of Autism and Developmental Disorders, 2017Co-Authors: Irene Sperandio, Katy L Unwin, Oriane Landry, Philippe A ChouinardAbstract:Deficits in perceptual constancies from early infancy have been proposed to contribute to autism and exacerbate its symptoms (Hellendoorn et al., Frontiers in Psychology 6:1–16, 2015). Here, we examined size constancy in adults from the general population (N = 106) with different levels of self-reported autistic traits using an approach based on negative Afterimages. The Afterimage strength, as indexed by duration and vividness, was also quantified. In opposition to the Hellendoorn and colleagues’ model, we were unable to demonstrate any kind of relationship between abilities in size constancy and autistic traits. However, our results demonstrated that individuals with higher degrees of autistic traits experienced more persistent Afterimages. We discuss possible retinal and post-retinal explanations for prolonged Afterimages in people with higher levels of autistic traits.
-
perceived size change induced by nonvisual signals in darkness the relative contribution of vergence and proprioception
The Journal of Neuroscience, 2013Co-Authors: Irene Sperandio, Shaleeza Kaderali, Philippe A Chouinard, Jared Frey, Melvyn A GoodaleAbstract:Most of the time, the human visual system computes perceived size by scaling the size of an object on the retina with its perceived distance. There are instances, however, in which size–distance scaling is not based on visual inputs but on extraretinal cues. In the Taylor illusion, the perceived Afterimage that is projected on an observer's hand will change in size depending on how far the limb is positioned from the eyes—even in complete darkness. In the dark, distance cues might derive from hand position signals either by an efference copy of the motor command to the moving hand or by proprioceptive input. Alternatively, there have been reports that vergence signals from the eyes might also be important. We performed a series of behavioral and eye-tracking experiments to tease apart how these different sources of distance information contribute to the Taylor illusion. We demonstrate that, with no visual information, perceived size changes mainly as a function of the vergence angle of the eyes, underscoring its importance in size–distance scaling. Interestingly, the strength of this relationship decreased when a mismatch between vergence and proprioception was introduced, indicating that proprioceptive feedback from the arm also affected size perception. By using Afterimages, we provide strong evidence that the human visual system can benefit from sensory signals that originate from the hand when visual information about distance is unavailable.
-
retinotopic activity in v1 reflects the perceived and not the retinal size of an Afterimage
Nature Neuroscience, 2012Co-Authors: Irene Sperandio, Philippe A Chouinard, Melvyn A GoodaleAbstract:An Afterimage looks larger when one fixates on a distant than on a closer surface. We show that the retinotopic activity in the primary visual cortex (V1) associated with viewing an Afterimage is modulated by perceived size, even when the size of the retinal image remains constant. This suggests that V1 has an important role in size constancy when the viewing distance of the stimulus changes.
-
Afterimage size is modulated by size contrast illusions
Journal of Visualization, 2012Co-Authors: Irene Sperandio, Armin Lak, Melvyn A GoodaleAbstract:Traditionally, the perceived size of negative Afterimages has been examined in relation to E. Emmert's law (1881), a size-distance equation that states that changes in perceived size of an Afterimage are a function of the distance of the surface on which it is projected. Here, we present evidence that the size of an Afterimage is also modulated by its surrounding context. We employed a new version of the Ebbinghaus-Titchener illusion with flickering surrounding stimuli and a static inner target that generated a vivid Afterimage of the latter but not the former. Observers were asked to give an initial manual estimate of the size of the inner target during the adaptation phase followed by another manual estimate of the size of the Afterimage during the test phase. Manual estimates were affected by the size-contrast illusion both when the surrounding contextual elements were present during Afterimage induction and when the surrounding elements were absent during the viewing of the Afterimage (Experiment 1). Such a modulation in perceived size, however, did not occur when observers viewed only the flickering surrounding context for a prolonged period of time and then estimated the size of a static target presented on the monitor afterward, demonstrating that flickering stimuli by themselves did not produce any aftereffect on perceived size (Experiment 2). Furthermore, in a final experiment, we showed that the modulation observed in the test phase of Experiment 1 was not due to memory of the manual estimates that had been performed during the adaptation phase (Experiment 3). These findings provide clear evidence for the role of high-level cognitive processes on the perceived size of an Afterimage beyond the retinal level. Thus, although retinal stimulation is required to induce an Afterimage, post-retinal factors influence its perceived size.
Blanke Olaf - One of the best experts on this subject based on the ideXlab platform.
-
Self-grounded vision: hand ownership modulates visual location through cortical beta and gamma oscillations
'Society for Neuroscience', 2017Co-Authors: Faivre Nathan, Doenz Jonathan, Scandola Michele, Dhanis Herberto, Bello Ruiz Javier, Bernasconi Fosco, Salomon Roy, Blanke OlafAbstract:International audienceVision is known to be shaped by context, defined by environmental and bodily signals. In the Taylor illusion, the size of an Afterimage projected on one's hand changes according to proprioceptive signals conveying hand position. Here, we assessed whether the Taylor illusion does not just depend on the physical hand position, but also on bodily self-consciousness as quantified through illusory hand ownership. Relying on the somatic rubber hand illusion, we manipulated hand ownership, such that participants embodied a rubber hand placed next to their own hand. We found that an Afterimage projected on the participant's hand drifted depending on illusory ownership between the participants' two hands, showing an implication of self-representation during the Taylor illusion. Oscillatory power analysis of electroencephalographic signals showed that illusory hand ownership was stronger in participants with stronger α suppression over left sensorimotor cortex, whereas the Taylor illusion correlated with higher β/γ power over frontotemporal regions. Higher γ connectivity between left sensorimotor and inferior parietal cortex was also found during illusory hand ownership. These data show that Afterimage drifts in the Taylor illusion do not only depend on the physical hand position but also on subjective ownership, which itself is based on the synchrony of somatosensory signals from the two hands. The effect of ownership on Afterimage drifts is associated with β/γ power and γ connectivity between frontoparietal regions and the visual cortex. Together, our results suggest that visual percepts are not only influenced by bodily context but are self-grounded, mapped on a self-referential frame.Vision is influenced by the body: in the Taylor illusion, the size of an Afterimage projected on one's hand changes according to tactile and proprioceptive signals conveying hand position. Here, we report a new phenomenon revealing that the perception of Afterimages depends not only on bodily signals, but also on the sense of self. Relying on the rubber hand illusion, we manipulated hand ownership, so that participants embodied a rubber hand placed next to their own hand. We found that visual Afterimages projected on the participant's hand drifted laterally, only when the rubber hand was embodied. Electroencephalography revealed spectral dissociations between somatic and visual effects, and higher γ connectivity along the dorsal visual pathways when the rubber hand was embodied
-
Self-grounded vision: hand ownership modulates visual location through cortical beta and gamma oscillations
'Society for Neuroscience', 2017Co-Authors: Faivre Nathan, Doenz Jonathan, Scandola Michele, Dhanis Herberto, Bello Ruiz Javier, Bernasconi Fosco, Salomon Roy, Blanke OlafAbstract:Vision is known to be shaped by context, defined by environmental and bodily signals. In the Taylor illusion, the size of an Afterimage projected on one's hand changes according to proprioceptive signals conveying hand position. Here, we assessed whether the Taylor illusion does not just depend on the physical hand position, but also on bodily self-consciousness as quantified through illusory hand ownership. Relying on the somatic rubber hand illusion, we manipulated hand ownership, such that participants embodied a rubber hand placed next to their own hand. We found that an Afterimage projected on the participant's hand drifted depending on illusory ownership between the participants' two hands, showing an implication of self-representation during the Taylor illusion. Oscillatory power analysis of electroencephalographic signals showed that illusory hand ownership was stronger in participants with stronger alpha suppression over left sensorimotor cortex, whereas the Taylor illusion correlated with higher beta/gamma power over frontotemporal regions. Higher gamma connectivity between left sensorimotor and inferior parietal cortex was also found during illusory hand ownership. These data show that Afterimage drifts in the Taylor illusion do not only depend on the physical hand position but also on subjective ownership, which itself is based on the synchrony of somatosensory signals from the two hands. The effect of ownership on Afterimage drifts is associated with beta/gamma power and gamma connectivity between frontoparietal regions and the visual cortex. Together, our results suggest that visual percepts are not only influenced by bodily context but are self-grounded, mapped on a self-referential frame
-
Self-Grounded Vision: Hand Ownership Modulates Visual Location through Cortical \u3b2 and \u3b3 Oscillations
'Society for Neuroscience', 2017Co-Authors: Faivre Nathan, Scandola Michele, Dhanis Herberto, Bello Ruiz Javier, Bernasconi Fosco, Salomon Roy, D\uf6nz Jonathan, Blanke OlafAbstract:Vision is known to be shaped by context, defined by environmental and bodily signals. In the Taylor illusion, the size of an Afterimage projected on one's hand changes according to proprioceptive signals conveying hand position. Here, we assessed whether the Taylor illusion does not just depend on the physical hand position, but also on bodily self-consciousness as quantified through illusory hand ownership. Relying on the somatic rubber hand illusion, we manipulated hand ownership, such that participants embodied a rubber hand placed next to their own hand. We found that an Afterimage projected on the participant's hand drifted depending on illusory ownership between the participants' two hands, showing an implication of self-representation during the Taylor illusion. Oscillatory power analysis of electroencephalographic signals showed that illusory hand ownership was stronger in participants with stronger \u3b1 suppression over left sensorimotor cortex, whereas the Taylor illusion correlated with higher \u3b2/\u3b3 power over frontotemporal regions. Higher \u3b3 connectivity between left sensorimotor and inferior parietal cortex was also found during illusory hand ownership. These data show that Afterimage drifts in the Taylor illusion do not only depend on the physical hand position but also on subjective ownership, which itself is based on the synchrony of somatosensory signals from the two hands. The effect of ownership on Afterimage drifts is associated with \u3b2/\u3b3 power and \u3b3 connectivity between frontoparietal regions and the visual cortex. Together, our results suggest that visual percepts are not only influenced by bodily context but are self-grounded, mapped on a self-referential frame
Melvyn A Goodale - One of the best experts on this subject based on the ideXlab platform.
-
perceived size change induced by nonvisual signals in darkness the relative contribution of vergence and proprioception
The Journal of Neuroscience, 2013Co-Authors: Irene Sperandio, Shaleeza Kaderali, Philippe A Chouinard, Jared Frey, Melvyn A GoodaleAbstract:Most of the time, the human visual system computes perceived size by scaling the size of an object on the retina with its perceived distance. There are instances, however, in which size–distance scaling is not based on visual inputs but on extraretinal cues. In the Taylor illusion, the perceived Afterimage that is projected on an observer's hand will change in size depending on how far the limb is positioned from the eyes—even in complete darkness. In the dark, distance cues might derive from hand position signals either by an efference copy of the motor command to the moving hand or by proprioceptive input. Alternatively, there have been reports that vergence signals from the eyes might also be important. We performed a series of behavioral and eye-tracking experiments to tease apart how these different sources of distance information contribute to the Taylor illusion. We demonstrate that, with no visual information, perceived size changes mainly as a function of the vergence angle of the eyes, underscoring its importance in size–distance scaling. Interestingly, the strength of this relationship decreased when a mismatch between vergence and proprioception was introduced, indicating that proprioceptive feedback from the arm also affected size perception. By using Afterimages, we provide strong evidence that the human visual system can benefit from sensory signals that originate from the hand when visual information about distance is unavailable.
-
retinotopic activity in v1 reflects the perceived and not the retinal size of an Afterimage
Nature Neuroscience, 2012Co-Authors: Irene Sperandio, Philippe A Chouinard, Melvyn A GoodaleAbstract:An Afterimage looks larger when one fixates on a distant than on a closer surface. We show that the retinotopic activity in the primary visual cortex (V1) associated with viewing an Afterimage is modulated by perceived size, even when the size of the retinal image remains constant. This suggests that V1 has an important role in size constancy when the viewing distance of the stimulus changes.
-
Afterimage size is modulated by size contrast illusions
Journal of Visualization, 2012Co-Authors: Irene Sperandio, Armin Lak, Melvyn A GoodaleAbstract:Traditionally, the perceived size of negative Afterimages has been examined in relation to E. Emmert's law (1881), a size-distance equation that states that changes in perceived size of an Afterimage are a function of the distance of the surface on which it is projected. Here, we present evidence that the size of an Afterimage is also modulated by its surrounding context. We employed a new version of the Ebbinghaus-Titchener illusion with flickering surrounding stimuli and a static inner target that generated a vivid Afterimage of the latter but not the former. Observers were asked to give an initial manual estimate of the size of the inner target during the adaptation phase followed by another manual estimate of the size of the Afterimage during the test phase. Manual estimates were affected by the size-contrast illusion both when the surrounding contextual elements were present during Afterimage induction and when the surrounding elements were absent during the viewing of the Afterimage (Experiment 1). Such a modulation in perceived size, however, did not occur when observers viewed only the flickering surrounding context for a prolonged period of time and then estimated the size of a static target presented on the monitor afterward, demonstrating that flickering stimuli by themselves did not produce any aftereffect on perceived size (Experiment 2). Furthermore, in a final experiment, we showed that the modulation observed in the test phase of Experiment 1 was not due to memory of the manual estimates that had been performed during the adaptation phase (Experiment 3). These findings provide clear evidence for the role of high-level cognitive processes on the perceived size of an Afterimage beyond the retinal level. Thus, although retinal stimulation is required to induce an Afterimage, post-retinal factors influence its perceived size.
Philippe A Chouinard - One of the best experts on this subject based on the ideXlab platform.
-
size constancy is preserved but Afterimages are prolonged in typical individuals with higher degrees of self reported autistic traits
Journal of Autism and Developmental Disorders, 2017Co-Authors: Irene Sperandio, Katy L Unwin, Oriane Landry, Philippe A ChouinardAbstract:Deficits in perceptual constancies from early infancy have been proposed to contribute to autism and exacerbate its symptoms (Hellendoorn et al., Frontiers in Psychology 6:1–16, 2015). Here, we examined size constancy in adults from the general population (N = 106) with different levels of self-reported autistic traits using an approach based on negative Afterimages. The Afterimage strength, as indexed by duration and vividness, was also quantified. In opposition to the Hellendoorn and colleagues’ model, we were unable to demonstrate any kind of relationship between abilities in size constancy and autistic traits. However, our results demonstrated that individuals with higher degrees of autistic traits experienced more persistent Afterimages. We discuss possible retinal and post-retinal explanations for prolonged Afterimages in people with higher levels of autistic traits.
-
perceived size change induced by nonvisual signals in darkness the relative contribution of vergence and proprioception
The Journal of Neuroscience, 2013Co-Authors: Irene Sperandio, Shaleeza Kaderali, Philippe A Chouinard, Jared Frey, Melvyn A GoodaleAbstract:Most of the time, the human visual system computes perceived size by scaling the size of an object on the retina with its perceived distance. There are instances, however, in which size–distance scaling is not based on visual inputs but on extraretinal cues. In the Taylor illusion, the perceived Afterimage that is projected on an observer's hand will change in size depending on how far the limb is positioned from the eyes—even in complete darkness. In the dark, distance cues might derive from hand position signals either by an efference copy of the motor command to the moving hand or by proprioceptive input. Alternatively, there have been reports that vergence signals from the eyes might also be important. We performed a series of behavioral and eye-tracking experiments to tease apart how these different sources of distance information contribute to the Taylor illusion. We demonstrate that, with no visual information, perceived size changes mainly as a function of the vergence angle of the eyes, underscoring its importance in size–distance scaling. Interestingly, the strength of this relationship decreased when a mismatch between vergence and proprioception was introduced, indicating that proprioceptive feedback from the arm also affected size perception. By using Afterimages, we provide strong evidence that the human visual system can benefit from sensory signals that originate from the hand when visual information about distance is unavailable.
-
retinotopic activity in v1 reflects the perceived and not the retinal size of an Afterimage
Nature Neuroscience, 2012Co-Authors: Irene Sperandio, Philippe A Chouinard, Melvyn A GoodaleAbstract:An Afterimage looks larger when one fixates on a distant than on a closer surface. We show that the retinotopic activity in the primary visual cortex (V1) associated with viewing an Afterimage is modulated by perceived size, even when the size of the retinal image remains constant. This suggests that V1 has an important role in size constancy when the viewing distance of the stimulus changes.
Faivre Nathan - One of the best experts on this subject based on the ideXlab platform.
-
Self-grounded vision: hand ownership modulates visual location through cortical beta and gamma oscillations
'Society for Neuroscience', 2017Co-Authors: Faivre Nathan, Doenz Jonathan, Scandola Michele, Dhanis Herberto, Bello Ruiz Javier, Bernasconi Fosco, Salomon Roy, Blanke OlafAbstract:International audienceVision is known to be shaped by context, defined by environmental and bodily signals. In the Taylor illusion, the size of an Afterimage projected on one's hand changes according to proprioceptive signals conveying hand position. Here, we assessed whether the Taylor illusion does not just depend on the physical hand position, but also on bodily self-consciousness as quantified through illusory hand ownership. Relying on the somatic rubber hand illusion, we manipulated hand ownership, such that participants embodied a rubber hand placed next to their own hand. We found that an Afterimage projected on the participant's hand drifted depending on illusory ownership between the participants' two hands, showing an implication of self-representation during the Taylor illusion. Oscillatory power analysis of electroencephalographic signals showed that illusory hand ownership was stronger in participants with stronger α suppression over left sensorimotor cortex, whereas the Taylor illusion correlated with higher β/γ power over frontotemporal regions. Higher γ connectivity between left sensorimotor and inferior parietal cortex was also found during illusory hand ownership. These data show that Afterimage drifts in the Taylor illusion do not only depend on the physical hand position but also on subjective ownership, which itself is based on the synchrony of somatosensory signals from the two hands. The effect of ownership on Afterimage drifts is associated with β/γ power and γ connectivity between frontoparietal regions and the visual cortex. Together, our results suggest that visual percepts are not only influenced by bodily context but are self-grounded, mapped on a self-referential frame.Vision is influenced by the body: in the Taylor illusion, the size of an Afterimage projected on one's hand changes according to tactile and proprioceptive signals conveying hand position. Here, we report a new phenomenon revealing that the perception of Afterimages depends not only on bodily signals, but also on the sense of self. Relying on the rubber hand illusion, we manipulated hand ownership, so that participants embodied a rubber hand placed next to their own hand. We found that visual Afterimages projected on the participant's hand drifted laterally, only when the rubber hand was embodied. Electroencephalography revealed spectral dissociations between somatic and visual effects, and higher γ connectivity along the dorsal visual pathways when the rubber hand was embodied
-
Self-grounded vision: hand ownership modulates visual location through cortical beta and gamma oscillations
'Society for Neuroscience', 2017Co-Authors: Faivre Nathan, Doenz Jonathan, Scandola Michele, Dhanis Herberto, Bello Ruiz Javier, Bernasconi Fosco, Salomon Roy, Blanke OlafAbstract:Vision is known to be shaped by context, defined by environmental and bodily signals. In the Taylor illusion, the size of an Afterimage projected on one's hand changes according to proprioceptive signals conveying hand position. Here, we assessed whether the Taylor illusion does not just depend on the physical hand position, but also on bodily self-consciousness as quantified through illusory hand ownership. Relying on the somatic rubber hand illusion, we manipulated hand ownership, such that participants embodied a rubber hand placed next to their own hand. We found that an Afterimage projected on the participant's hand drifted depending on illusory ownership between the participants' two hands, showing an implication of self-representation during the Taylor illusion. Oscillatory power analysis of electroencephalographic signals showed that illusory hand ownership was stronger in participants with stronger alpha suppression over left sensorimotor cortex, whereas the Taylor illusion correlated with higher beta/gamma power over frontotemporal regions. Higher gamma connectivity between left sensorimotor and inferior parietal cortex was also found during illusory hand ownership. These data show that Afterimage drifts in the Taylor illusion do not only depend on the physical hand position but also on subjective ownership, which itself is based on the synchrony of somatosensory signals from the two hands. The effect of ownership on Afterimage drifts is associated with beta/gamma power and gamma connectivity between frontoparietal regions and the visual cortex. Together, our results suggest that visual percepts are not only influenced by bodily context but are self-grounded, mapped on a self-referential frame
-
Self-Grounded Vision: Hand Ownership Modulates Visual Location through Cortical \u3b2 and \u3b3 Oscillations
'Society for Neuroscience', 2017Co-Authors: Faivre Nathan, Scandola Michele, Dhanis Herberto, Bello Ruiz Javier, Bernasconi Fosco, Salomon Roy, D\uf6nz Jonathan, Blanke OlafAbstract:Vision is known to be shaped by context, defined by environmental and bodily signals. In the Taylor illusion, the size of an Afterimage projected on one's hand changes according to proprioceptive signals conveying hand position. Here, we assessed whether the Taylor illusion does not just depend on the physical hand position, but also on bodily self-consciousness as quantified through illusory hand ownership. Relying on the somatic rubber hand illusion, we manipulated hand ownership, such that participants embodied a rubber hand placed next to their own hand. We found that an Afterimage projected on the participant's hand drifted depending on illusory ownership between the participants' two hands, showing an implication of self-representation during the Taylor illusion. Oscillatory power analysis of electroencephalographic signals showed that illusory hand ownership was stronger in participants with stronger \u3b1 suppression over left sensorimotor cortex, whereas the Taylor illusion correlated with higher \u3b2/\u3b3 power over frontotemporal regions. Higher \u3b3 connectivity between left sensorimotor and inferior parietal cortex was also found during illusory hand ownership. These data show that Afterimage drifts in the Taylor illusion do not only depend on the physical hand position but also on subjective ownership, which itself is based on the synchrony of somatosensory signals from the two hands. The effect of ownership on Afterimage drifts is associated with \u3b2/\u3b3 power and \u3b3 connectivity between frontoparietal regions and the visual cortex. Together, our results suggest that visual percepts are not only influenced by bodily context but are self-grounded, mapped on a self-referential frame