Ryota Kanai
University of Sussex, Psychology, Faculty Member
- Psychology, Visual Studies, Cognitive Neuroscience, Neuroimaging, Visual attention, Visual Neuroscience, and 12 moreNeuroscience, Metacognition, Face perception, Consciousness, Attitude change, Variability, Visual Attention & Awareness, Neural correlates of consciousness, Binocular Rivalry, Prediction error, Bistable Preception, and Educationedit
Abstract We effortlessly and seemingly instantaneously recognize thousands of objects, although we rarely—if ever—see the same image of an object twice. The retinal image of an object can vary by context, size, viewpoint, illumination,... more
Abstract We effortlessly and seemingly instantaneously recognize thousands of objects, although we rarely—if ever—see the same image of an object twice. The retinal image of an object can vary by context, size, viewpoint, illumination, and location. The present study examined how the visual system abstracts object category across variations in retinal location.
When visual input is inconclusive, does previous experience aid the visual system in attaining an accurate perceptual interpretation? Prolonged viewing of a visually ambiguous stimulus causes perception to alternate between conflicting... more
When visual input is inconclusive, does previous experience aid the visual system in attaining an accurate perceptual interpretation? Prolonged viewing of a visually ambiguous stimulus causes perception to alternate between conflicting interpretations. When viewed intermittently, however, ambiguous stimuli tend to evoke the same percept on many consecutive presentations.
Abstract Perceived color at a point in space is not determined simply by the color directly stimulating the corresponding retinal position. Surface color is informed by flanking edge signals, which also serve to inhibit the intrusion of... more
Abstract Perceived color at a point in space is not determined simply by the color directly stimulating the corresponding retinal position. Surface color is informed by flanking edge signals, which also serve to inhibit the intrusion of signals from neighboring surfaces. Spatially continuous local interactions among color and luminance signals have been implicated in a propagation process often referred to as filling-in.
Abstract During prolonged fixation, visual objects presented in the periphery of the visual field often fade from awareness. This phenomenon, known as the Troxler effect, has been largely attributed to adaptation of neurons responding to... more
Abstract During prolonged fixation, visual objects presented in the periphery of the visual field often fade from awareness. This phenomenon, known as the Troxler effect, has been largely attributed to adaptation of neurons responding to peripheral targets. Here, we hypothesized that perceptual disappearance might result from degeneration of feedback from attention-related cortical areas to early visual areas and that visual transients disrupt the feedback loop sustaining low-level signals and thereby trigger perceptual fading.
Abstract Perceptual priming is generally regarded as a passive and automatic process, as it is obtained even without awareness of the prime. Recent studies have introduced a more active form of perceptual priming in which priming for a... more
Abstract Perceptual priming is generally regarded as a passive and automatic process, as it is obtained even without awareness of the prime. Recent studies have introduced a more active form of perceptual priming in which priming for a subsequent ambiguous stimulus is triggered by the subjective percept, that is, interpretation of a previous ambiguous stimulus. This phenomenon known as stabilization does not require a conscious effort to actively maintain one perceptual interpretation.
Abstract We show that previewing one half image of a binocular rivalry pair can cause it to gain initial dominance when the other half is added, a novel phenomenon we term flash facilitation. This is the converse of a known effect called... more
Abstract We show that previewing one half image of a binocular rivalry pair can cause it to gain initial dominance when the other half is added, a novel phenomenon we term flash facilitation. This is the converse of a known effect called flash suppression, where the previewed image becomes suppressed upon rivalrous presentation. The exact effect of previewing an image depends on both the duration and the contrast of the prior stimulus.
When visual input has conflicting interpretations, conscious perception can alternate spontaneously between competing interpretations [1]. There is a large amount of unexplained variability between individuals in the rate of such... more
When visual input has conflicting interpretations, conscious perception can alternate spontaneously between competing interpretations [1]. There is a large amount of unexplained variability between individuals in the rate of such spontaneous alternations in perception [2–5]. We hypothesized that variability in perceptual rivalry might be reflected in individual differences in brain structure, because brain structure can exhibit systematic relationships with an individual's cognitive experiences and skills [6–9].
Abstract The human brain exhibits remarkable interindividual variability in cortical architecture. Despite extensive evidence for the behavioral consequences of such anatomical variability in individual cortical regions, it is unclear... more
Abstract The human brain exhibits remarkable interindividual variability in cortical architecture. Despite extensive evidence for the behavioral consequences of such anatomical variability in individual cortical regions, it is unclear whether and how different cortical regions covary in morphology.
Abstract Inter-individual variability in perception, thought and action is frequently treated as a source of'noise'in scientific investigations of the neural mechanisms that underlie these processes, and discarded by averaging data from a... more
Abstract Inter-individual variability in perception, thought and action is frequently treated as a source of'noise'in scientific investigations of the neural mechanisms that underlie these processes, and discarded by averaging data from a group of participants.
Abstract When our visual system is confronted with ambiguous stimuli, the perceptual interpretation spontaneously alternates between the competing incompatible interpretations. The timing of such perceptual alternations is highly... more
Abstract When our visual system is confronted with ambiguous stimuli, the perceptual interpretation spontaneously alternates between the competing incompatible interpretations. The timing of such perceptual alternations is highly stochastic and the underlying neural mechanisms are poorly understood. Here, we show that perceptual alternations can be triggered by a transient stimulus presented nearby.
Abstract We all appreciate that some of our friends and colleagues are more distractible than others. This variability can be captured by pencil and paper questionnaires in which individuals report such cognitive failures in their... more
Abstract We all appreciate that some of our friends and colleagues are more distractible than others. This variability can be captured by pencil and paper questionnaires in which individuals report such cognitive failures in their everyday life. Surprisingly, these self-report measures have high heritability, leading to the hypothesis that distractibility might have a basis in brain structure.
Loneliness is the distressing feeling associated with the perceived absence of satisfying social relationships [1]. Loneliness is increasingly prevalent in modern societies [2, 3] and has detrimental effects on health and happiness [4,... more
Loneliness is the distressing feeling associated with the perceived absence of satisfying social relationships [1]. Loneliness is increasingly prevalent in modern societies [2, 3] and has detrimental effects on health and happiness [4, 5]. Although situational threats to social relationships can transiently induce the emotion of loneliness, susceptibility to loneliness is a stable trait that varies across individuals [6–8] and is to some extent heritable [9–11].
Abstract The ability to estimate duration is essential to human behavior, yet people vary greatly in their ability to estimate time and the brain structures mediating this inter-individual variability remain poorly understood. Here, we... more
Abstract The ability to estimate duration is essential to human behavior, yet people vary greatly in their ability to estimate time and the brain structures mediating this inter-individual variability remain poorly understood. Here, we showed that inter-individual variability in duration estimation was highly correlated across visual and auditory modalities but depended on the scale of temporal duration.
Abstract When faced with inconclusive or conflicting visual input human observers experience one of multiple possible perceptions. One factor that determines perception of such an ambiguous stimulus is how the same stimulus was perceived... more
Abstract When faced with inconclusive or conflicting visual input human observers experience one of multiple possible perceptions. One factor that determines perception of such an ambiguous stimulus is how the same stimulus was perceived on previous occasions, a phenomenon called perceptual memory. We examined perceptual memory of an ambiguous motion stimulus while applying transcranial magnetic stimulation (TMS) to the motion-sensitive areas of the middle temporal cortex (hMT+).
When visual input is inconclusive, does previous experience aid the visual system in attaining an accurate perceptual interpretation? Prolonged viewing of a visually ambiguous stimulus causes perception to alternate between conflicting... more
When visual input is inconclusive, does previous experience aid the visual system in attaining an accurate perceptual interpretation? Prolonged viewing of a visually ambiguous stimulus causes perception to alternate between conflicting interpretations. When viewed intermittently, however, ambiguous stimuli tend to evoke the same percept on many consecutive presentations.
Background The timing at which sensory input reaches the level of conscious perception is an intriguing question still awaiting an answer. It is often assumed that both visual and auditory percepts have a modality specific processing... more
Background The timing at which sensory input reaches the level of conscious perception is an intriguing question still awaiting an answer. It is often assumed that both visual and auditory percepts have a modality specific processing delay and their difference determines perceptual temporal offset.
Abstract Motion perception in a small region of the visual field is influenced by motion in the immediately surrounding regions. We studied this influence by a center-surround paradigm, where the perception of motion in a central circular... more
Abstract Motion perception in a small region of the visual field is influenced by motion in the immediately surrounding regions. We studied this influence by a center-surround paradigm, where the perception of motion in a central circular region is influenced (biased) by motion in a surrounding annulus. We investigated the contribution of surround timing to the surround bias. The magnitude of surround bias for different onset delays between center and surround was quantified.
We effortlessly and seemingly instantaneously recognize thousands of objects, although we rarelyVif everVsee the same image of an object twice. The retinal image of an object can vary by context, size, viewpoint, illumination, and... more
We effortlessly and seemingly instantaneously recognize thousands of objects, although we rarelyVif everVsee the same image of an object twice. The retinal image of an object can vary by context, size, viewpoint, illumination, and location. The present study examined how the visual system abstracts object category across variations in retinal location. In three experiments, participants viewed images of objects presented to different retinal locations while brain activity was recorded using magnetoencephalography (MEG).
Abstract People often fail to select and encode the second of two targets presented within less than 500 ms in rapid serial visual presentation (RSVP), an effect known as the attentional blink. We investigated how report of the two... more
Abstract People often fail to select and encode the second of two targets presented within less than 500 ms in rapid serial visual presentation (RSVP), an effect known as the attentional blink. We investigated how report of the two targets is affected when one of them is maintained in working memory for a secondary, memory-search task. The results showed that report of either target was impaired when it was a member of the memory set relative to when it was not.
Having looked at other articles on schalorpedia, I'm convinced that articles on scholarpedia become most useful for readers when they provide detailed descriptions of a specific topic (just like TICS or Nature Reviews Neuroscience). In... more
Having looked at other articles on schalorpedia, I'm convinced that articles on scholarpedia become most useful for readers when they provide detailed descriptions of a specific topic (just like TICS or Nature Reviews Neuroscience). In the case of the target article on attention, I felt uncomfortable to take it as the main scholarpedia article on attention, as attention is such a broad term and studied in many different fields of neurosciences.
When faced with ambiguous sensory input, conscious awareness may alternate between the different percepts that are consistent with the input. Visual phenomena leading to such multistable perception, where constant sensory input evokes... more
When faced with ambiguous sensory input, conscious awareness may alternate between the different percepts that are consistent with the input. Visual phenomena leading to such multistable perception, where constant sensory input evokes different conscious percepts, are particularly useful for investigating the processes underlying perceptual awareness [1].
Abstract Transcranial direct current stimulation (tDCS) has been successfully applied to cortical areas such as the motor cortex and visual cortex. In the present study, we examined whether tDCS can reach and selectively modulate the... more
Abstract Transcranial direct current stimulation (tDCS) has been successfully applied to cortical areas such as the motor cortex and visual cortex. In the present study, we examined whether tDCS can reach and selectively modulate the excitability of the frontal eye field (FEF). In order to assess potential effects of tDCS, we measured saccade latency, landing point, and its variability in a simple prosaccade task and in an antisaccade task.
Oscillatory neuronal activities are commonly observed in response to sensory stimulation. However, their functional roles are still the subject of debate. One-way to probe the roles of oscillatory neural activities is to deliver... more
Oscillatory neuronal activities are commonly observed in response to sensory stimulation. However, their functional roles are still the subject of debate. One-way to probe the roles of oscillatory neural activities is to deliver alternating current to the cortex at biologically relevant frequencies and examine whether such stimulation influences perception and cognition.
Abstract Bodily perception is increasingly a focus of philosophical discussion, in both the analytic and continental traditions. It has been linked to such issues as human agency and the self (Bermudez, Marcel, & Eilan, 1995; Legrand,... more
Abstract Bodily perception is increasingly a focus of philosophical discussion, in both the analytic and continental traditions. It has been linked to such issues as human agency and the self (Bermudez, Marcel, & Eilan, 1995; Legrand, 2006), as well as more broad topics in the philosophy of cognitive science, due to the increasing popularity of embodied approaches to cognition (Clark, 1999; Clark, 2003; Gallagher, 2005).
Some people conform more than others. Across different contexts, this tendency is a fairly stable trait [1]. This stability suggests that the tendency to conform might have an anatomical correlate [2]. Values that one associates with... more
Some people conform more than others. Across different contexts, this tendency is a fairly stable trait [1]. This stability suggests that the tendency to conform might have an anatomical correlate [2]. Values that one associates with available options, from foods to political candidates, help to guide choices and behaviour. These values can often be updated by the expressed preferences of other people as much as by independent experience.
Expertise in non-visual domains such as musical performance is associated with differences in gray matter volume of particular regions of the human brain. Whether this is also the case for expertise in visual object recognition is... more
Expertise in non-visual domains such as musical performance is associated with differences in gray matter volume of particular regions of the human brain. Whether this is also the case for expertise in visual object recognition is unknown. Here we tested whether individual variability in the ability to recognize car models, from novice performance to high level of expertise, is associated with specific structural changes in gray matter volume.
Moral sentiment has been hypothesized to reflect evolved adaptations to social living. If so, individual differences in moral values may relate to regional variation in brain structure. We tested this hypothesis in a sample of 70 young,... more
Moral sentiment has been hypothesized to reflect evolved adaptations to social living. If so, individual differences in moral values may relate to regional variation in brain structure. We tested this hypothesis in a sample of 70 young, healthy adults examining whether differences on two major dimensions of moral values were significantly associated with regional gray matter volume.
Abstract Visual perception can be modulated by sounds. A drastic example of this is the sound-induced flash illusion: when a single flash is accompanied by two bleeps, it is sometimes perceived in an illusory fashion as two consecutive... more
Abstract Visual perception can be modulated by sounds. A drastic example of this is the sound-induced flash illusion: when a single flash is accompanied by two bleeps, it is sometimes perceived in an illusory fashion as two consecutive flashes. However, there are strong individual differences in proneness to this illusion. Some participants experience the illusion on almost every trial, whereas others almost never do.
Abstract Colour has been shown to facilitate the recognition of scene-images, but only when these images contain natural scenes, for which colour is 'diagnostic'. Here we investigate whether colour can also facilitate memory for scene... more
Abstract Colour has been shown to facilitate the recognition of scene-images, but only when these images contain natural scenes, for which colour is 'diagnostic'. Here we investigate whether colour can also facilitate memory for scene images, and whether this would hold for natural scenes in particular. In the first experiment participants first studied a set of colour and greyscale natural and man-made scene images. Next, the same images were presented, randomly mixed with a different set.
Abstract. The position of a moving object is often mislocalised in the direction of movement. At the input stage of visual processing, the position of a moving object should still be represented veridically, whereas it should become... more
Abstract. The position of a moving object is often mislocalised in the direction of movement. At the input stage of visual processing, the position of a moving object should still be represented veridically, whereas it should become closer to the mislocalised position at a later processing stage responsible for positional judgment. Here, we show that visual transients expose the veridical position of a moving object represented in early visual areas.
Empathy is a multi-faceted concept consisting of our ability not only to share emotions but also to exert cognitive control and perspective taking in our interactions with others. Here we examined whether inter-individual variability in... more
Empathy is a multi-faceted concept consisting of our ability not only to share emotions but also to exert cognitive control and perspective taking in our interactions with others. Here we examined whether inter-individual variability in different components of empathy was related to differences in brain structure assessed using voxel-based morphometry. Following a magnetic resonance imaging (MRI) scan, participants completed the Interpersonal Reactivity Index (IRI).
Abstract Oscillatory neuronal activities are commonly observed in response to sensory stimulation. However, their functional roles are still the subject of debate. One-way to probe the roles of oscillatory neural activities is to deliver... more
Abstract Oscillatory neuronal activities are commonly observed in response to sensory stimulation. However, their functional roles are still the subject of debate. One-way to probe the roles of oscillatory neural activities is to deliver alternating current to the cortex at biologically relevant frequencies and examine whether such stimulation influences perception and cognition.
Abstract After viewing directional motion, one is likely to perceive a subsequently presented directionally ambiguous motion as being in the same direction as the prior motion. The perceptual bias towards the most recent percept gradually... more
Abstract After viewing directional motion, one is likely to perceive a subsequently presented directionally ambiguous motion as being in the same direction as the prior motion. The perceptual bias towards the most recent percept gradually develops as the interval between the prior stimulus and a subsequent test becomes longer. This form of positive bias, or priming, is created in an automatic fashion. It remain unclear how such perceptual bias could be eliminated by a stimulus manipulation.
Abstract It has been argued that both modality-specific and supramodal mechanisms dedicated to time perception underlie the estimation of interval durations. While it is generally assumed that early sensory areas are dedicated to... more
Abstract It has been argued that both modality-specific and supramodal mechanisms dedicated to time perception underlie the estimation of interval durations. While it is generally assumed that early sensory areas are dedicated to modality-specific time estimation, we hypothesized that early sensory areas such as the primary visual cortex or the auditory cortex might be involved in time perception independently of the sensory modality of the input.
Abstract Visual rivalry is thought to be a distributed process that simultaneously takes place at multiple levels in the visual processing hierarchy. Also, the different types of rivalry, such as binocular and monocular rivalry, are... more
Abstract Visual rivalry is thought to be a distributed process that simultaneously takes place at multiple levels in the visual processing hierarchy. Also, the different types of rivalry, such as binocular and monocular rivalry, are thought to engage shared underlying mechanisms. We hypothesized that the amount of perceptual suppression during rivalry as measured by the total duration of fully exclusive perceptual dominance is determined by a distance in a neurally represented feature space.
Human behavior depends on the ability to effectively introspect about our performance. For simple perceptual decisions, this introspective or metacognitive ability varies substantially across individuals and is correlated with the... more
Human behavior depends on the ability to effectively introspect about our performance. For simple perceptual decisions, this introspective or metacognitive ability varies substantially across individuals and is correlated with the structure of focal areas in prefrontal cortex. This raises the possibility that the ability to introspect about different perceptual decisions might be mediated by a common cognitive process.
Conscious visual perception can fail in many circumstances. However, little is known about the causes and processes leading to failures of visual awareness. In this study, we introduce a new signal detection measure termed subjective... more
Conscious visual perception can fail in many circumstances. However, little is known about the causes and processes leading to failures of visual awareness. In this study, we introduce a new signal detection measure termed subjective discriminability of invisibility (SDI) that allows one to distinguish between subjective blindness due to reduction of sensory signals or to lack of attentional access to sensory signals.
When faced with ambiguous sensory input, conscious awareness may alternate between the different percepts that are consistent with the input. Visual phenomena leading to such multistable perception, where constant sensory input evokes... more
When faced with ambiguous sensory input, conscious awareness may alternate between the different percepts that are consistent with the input. Visual phenomena leading to such multistable perception, where constant sensory input evokes different conscious percepts, are particularly useful for investigating the processes underlying perceptual awareness [1].
Abstract Over the history of the study of visual perception there has been great success at discovering countless visual illusions. There has been less success in organizing the overwhelming variety of illusions into empirical... more
Abstract Over the history of the study of visual perception there has been great success at discovering countless visual illusions. There has been less success in organizing the overwhelming variety of illusions into empirical generalizations (much less explaining them all via a unifying theory). Here, this article shows that it is possible to systematically organize more than 50 kinds of illusion into a 7× 4 matrix of 28 classes.
Abstract When each of the two eyes is confronted with a dissimilar stimulus, the percept will generally alternate between the two. This phenomenon is known as binocular rivalry. Although binocular rivalry occurs for locations where... more
Abstract When each of the two eyes is confronted with a dissimilar stimulus, the percept will generally alternate between the two. This phenomenon is known as binocular rivalry. Although binocular rivalry occurs for locations where targets overlap spatially, the area surrounding rivalrous targets can modulate their dominance.
Across cultures, social relationships are often thought of, described, and acted out in terms of physical space (eg “close friends”“high lord”). Does this cognitive mapping of social concepts arise from shared brain resources for... more
Across cultures, social relationships are often thought of, described, and acted out in terms of physical space (eg “close friends”“high lord”). Does this cognitive mapping of social concepts arise from shared brain resources for processing social and physical relationships? Using fMRI, we found that the tasks of evaluating social compatibility and of evaluating physical distances engage a common brain substrate in the parietal cortex.
We often associate moving objects and changing pitch, eg, falling stones with descending, and launching rockets with ascending pitch, even when these sounds do not happen in the real-world. The reason for this is unknown. Here we report... more
We often associate moving objects and changing pitch, eg, falling stones with descending, and launching rockets with ascending pitch, even when these sounds do not happen in the real-world. The reason for this is unknown. Here we report an illusion in which auditory stimuli with no apparent spatial and motion information alter human visual motion perception.
Abstract We investigated the effects of different viewpoints on remapping visuo-motor space, and whether remapping happens differently during the planning and the online control phase of goal-directed movements. Participants tapped... more
Abstract We investigated the effects of different viewpoints on remapping visuo-motor space, and whether remapping happens differently during the planning and the online control phase of goal-directed movements. Participants tapped targets on a monitor that was placed horizontally flat and flush with the table in front of them. They viewed the layout of the scene, including the monitor, and their hand, through video goggles attached to a camera. The camera could be moved along a semi-circle with the monitor as the circle's center.
Around 20% of the population exhibits moderate to severe numerical disabilities [1–3], and a further percentage loses its numerical competence during the lifespan as a result of stroke or degenerative diseases [4]. In this work, we... more
Around 20% of the population exhibits moderate to severe numerical disabilities [1–3], and a further percentage loses its numerical competence during the lifespan as a result of stroke or degenerative diseases [4]. In this work, we investigated the feasibility of using noninvasive stimulation to the parietal lobe during numerical learning to selectively improve numerical abilities.
Abstract The increasing ubiquity of web-based social networking services is a striking feature of modern human society. The degree to which individuals participate in these networks varies substantially for reasons that are unclear.
Abstract When you see a red ball rolling across the floor, the ball's redness, roundness and motion appear to be unified and inseparably bound together as features of the ball. But neurophysiological evidence indicates that visual... more
Abstract When you see a red ball rolling across the floor, the ball's redness, roundness and motion appear to be unified and inseparably bound together as features of the ball. But neurophysiological evidence indicates that visual features such as colour, shape and motion are processed in separate regions of the brain 1. Here we describe an illusion that exploits this separation, causing colour and motion to be recombined incorrectly while a stable stimulus is being viewed continuously.
Summary Substantial differences exist in the cognitive styles of liberals and conservatives on psychological measures [1]. Variability in political attitudes reflects genetic influences and their interaction with environmental factors... more
Summary Substantial differences exist in the cognitive styles of liberals and conservatives on psychological measures [1]. Variability in political attitudes reflects genetic influences and their interaction with environmental factors [[2] and [3]]. Recent work has shown a correlation between liberalism and conflict-related activity measured by event-related potentials originating in the anterior cingulate cortex [4]. Here we show that this functional correlate of political attitudes has a counterpart in brain structure.
Abstract Recent psychophysical studies have shown that perceived timings of events can be dissociated from their physical temporal relationship. In the flash-lag effect (FLE), a flash presented at the same spatiotemporal position as a... more
Abstract Recent psychophysical studies have shown that perceived timings of events can be dissociated from their physical temporal relationship. In the flash-lag effect (FLE), a flash presented at the same spatiotemporal position as a continuously moving stimulus is perceived to lag behind the moving stimulus. In the present study, we report a peculiar condition in which FLE does not occur even when the position of a moving object is estimated at the moment of a transient event.
Abstract We report a distortion of subjective time perception in which the duration of a first interval is perceived to be longer than the succeeding interval of the same duration. The amount of time expansion depends on the onset type... more
Abstract We report a distortion of subjective time perception in which the duration of a first interval is perceived to be longer than the succeeding interval of the same duration. The amount of time expansion depends on the onset type defining the first interval. When a stimulus appears abruptly, its duration is perceived to be longer than when it appears following a stationary array.