Naotsugu Tsuchiya

Monash University (Australia) · school of psychological sciences

Since Tversky argued that similarity judgments violate the three metric axioms, asymmetrical similarity judgments have been particularly challenging for standard, geometric models of similarity, such as multidimensional scaling. According to Tversky, asymmetrical similarity judgments are driven by differences in salience or extent of knowledge. How...

Mediano et al. (1. Mediano 2022 TICS) separate out strong and weak flavours of the integrated information theory (IIT) of consciousness. They describe “strong IIT” as attempting to derive a universal formula for consciousness, and “weak IIT” as searching for empirically measurable correlates of aspects of consciousness. We put forward that their ov...

It seems obvious to lay people that neurotypical humans experience color equivalently across their entire visual field. To some neuroscientists, psychologists and philosophers though, this claim has been met with skepticism, as neurophysiological evidence indicates the mechanisms that support color perception degrade with eccentricity. However, the...

A fundamental question in the study of consciousness is "To what extent are sensory experiences equivalent between individuals?'' One promising approach is to intersubjectively compare the similarity relationships of sensory experiences, named "qualia structures''. An issue with existing methods is the assumption that sensory experiences evoked by...

What is the nature of the relationship between qualia, or contents of consciousness, and behavioral reports? Traditionally, this type of question has been only addressed via a qualitative and philosophical approach. Some theorists emphasize an incomplete and inaccurate nature of reports of one’s own qualia to discourage formal research programs on...

Background: A majority of previous studies appear to support a view that human observers can only perceive coarse information from a natural scene image when it is presented rapidly (<100ms, masked). In these studies, participants were often forced to choose an answer from options that experimenters preselected. These options can underestimate what...

The widely used guidelines for sleep staging were developed for the visual inspection of electrophysiological recordings by the human eye. As such, these rules reflect a limited range of features in these data and are therefore restricted in accurately capturing the physiological changes associated with sleep. Here we present a novel analysis frame...

Upon a brief glance, how well can we differentiate what we see from what we do not? Previous studies answered this question as ‘poorly’. This is in stark contrast with our everyday experience. Here, we consider the possibility that previous restriction in stimulus variability and response alternatives reduced what participants could express from wh...

The folk psychological notion that “we see what we expect to see” is supported by evidence that we become consciously aware of visual stimuli that match our prior expectations more quickly than stimuli that violate our expectations. Similarly, “we see what we want to see,” such that more biologically-relevant stimuli are also prioritised for consci...

Qualitative relationships between two instances of conscious experiences can be quantified through the perceived similarity. Previously, we proposed that by defining similarity relationships as arrows and conscious experiences as objects, we can define a category of qualia in the context of category theory. However, the example qualia categories we...

How a system generates conscious experience remains an elusive question. One approach towards answering this is to consider the information available in the system from the perspective of the system itself. Integrated information theory (IIT) proposes a measure to capture this integrated information (Φ). While Φ can be computed at any spatiotempora...

Rapidly detecting salient information in our environments is critical for survival. Visual processing in subcortical areas like the pulvinar and amygdala has been shown to facilitate unconscious processing of salient stimuli. It is unknown, however, if and how these areas might interact with cortical regions to facilitate faster conscious perceptio...

Background: Contemporary societies lack direct evidence that diversity of neuro-origin psychological traits – neurodiversity – benefits the human species. Psychological diversities including those with heightened traits of obsessive-compulsiveness (OC) may play a critical preventative role amidst a pandemic because of their natural dispositions for...

Upon a brief glance, how well can we differentiate what we see from what we do not? Previous studies answered this question as “poorly”. This is in stark contrast with our everyday experience. Here, we consider the possibility that previous restriction in stimulus variability and response alternatives reduced what participants could express from wh...

How a system generates conscious experience remains an elusive question. One approach towards answering this is to consider the information available in the system from the perspective of the system itself. Integrated information theory (IIT) proposes a measure to capture this, integrated information (Φ). While Φ can be computed at any spatiotempor...

Objectif Les règles établies pour la classification du sommeil ont été développées pour l’inspection visuelle des enregistrements électrophysiologiques. Ainsi, ces règles ne prennent en compte que certaines propriétés du signal, ce qui limite l’étude des changements physiologiques se manifestant pendant le sommeil. Dans cette étude, nous présentons...

The relationship between consciousness and working memory (WM) has been recently debated both at the theoretical and methodological levels (Persuh et al., 2018; Velichkovsky, 2017). While there is behavioral and neural evidence that argues for the existence of unconscious WM, several methodological concerns have been raised, rendering this issue hi...

Scientists have developed hundreds of techniques to measure the interactions between pairs of processes in complex systems. But these computational methods -- from correlation coefficients to causal inference -- rely on distinct quantitative theories that remain largely disconnected. Here we introduce a library of 249 statistics for pairwise intera...

Background: A majority of previous studies appear to support a view that human observers can only perceive coarse information from a natural scene image when it is presented rapidly (<100ms, masked). In these studies, participants were often forced to choose an answer from options that experimenters preselected. These options can underestimate what...

Since Tversky (1977) argued that similarity judgments violate the three metric axioms, asymmetrical similarity judgments have been offered as particularly difficult challenges for standard, geometric models of similarity, such as multidimensional scaling. According to Tversky (1977), asymmetrical similarity judgments are driven by differences in sa...

Characterizing consciousness in and of itself is notoriously difficult. Here, we propose an alternative approach to characterize, and eventually define, consciousness through exhaustive descriptions of consciousness’ relationships to all other consciousness. This approach is founded in category theory. Indeed, category theory can prove that two obj...

The relationship between consciousness and working memory (WM) has been recently debated both at the theoretical and methodological levels (Persuh et al., 2018; Velichkovsky, 2017). While there is behavioral and neural evidence that argues for the existence of unconscious WM, several methodological concerns have been raised, rendering this issue hi...

Previous studies have established a view that human observers can only perceive coarse information from a natural scene image when it is presented rapidly (<100ms, masked). In these studies, participants were often forced to choose an answer from options that experimenters preselected. These options can underestimate what participants experience an...

The interaction between the thalamus and sensory cortex plays critical roles in sensory processing. Previous studies have revealed pathway-specific synaptic properties of thalamo-cortical connections. However, few studies to date have investigated how each pathway routes moment-to-moment information. Here, we simultaneously recorded neural activity...

The widely used guidelines for sleep staging were developed for the visual inspection of electrophysiological recordings by the human eye. As such, these rules reflect only a limited range of features in these data and are therefore restricted in accurately capturing the physiological changes that occur during sleep. Here we present a novel analysi...

Rapidly detecting salient information in our environments is critical for survival. Visual processing in subcortical areas like the pulvinar and amygdala have been shown to facilitate unconscious processing of salient stimuli. It is unknown, however, if and how these areas might interact with cortical networks to facilitate faster conscious percept...

Qualitative relationships between two instances of conscious experiences can be quantified through the perceived similarity. Previously, we proposed that by defining similarity relationships as arrows and conscious experiences as objects, we can define a category of qualia in the context of category theory. However, the example qualia categories we...

Attentional lapses occur commonly and are associated with mind wandering, where focus is turned to thoughts unrelated to ongoing tasks and environmental demands, or mind blanking, where the stream of consciousness itself comes to a halt. To understand the neural mechanisms underlying attentional lapses, we studied the behaviour, subjective experien...

Qualitative relationships between two instances of conscious experiences can be quantified through the perceived similarity. Previously, we proposed that by defining similarity relationships as arrows and conscious experiences as objects, we can define a category of qualia in the context of category theory. However, the example qualia categories we...

Several previous studies have interfered with the observer’s facial mimicry during a variety of facial expression recognition tasks providing evidence in favor of the role of facial mimicry and sensorimotor activity in emotion processing. In this theoretical context, a particularly intriguing facet has been neglected, namely whether blocking facial...

When presented with an oscillatory sensory input at a particular frequency, F [Hz], neural systems respond with the corresponding frequency, f [Hz], and its multiples. When the input includes two frequencies ( F1 and F2 ) and they are nonlinearly integrated in the system, responses at intermodulation frequencies (i.e., n1 * f1 + n2 * f2 [Hz], where...

The physical basis of consciousness remains one of the most elusive concepts in current science. One influential conjecture is that consciousness is to do with some form of causality, measurable through information. The integrated information theory of consciousness (IIT) proposes that conscious experience, filled with rich and specific content, co...

12-week lecture series on "the neural basis of consciousness" by Prof Nao Tsuchiya. Given to 3rd year undergraduate level. No prerequisites. Contents: a. Why are we interested in consciousness?b. What do we mean by consciousness?c. How can we study consciousness?d. What are the potential problems when one wants tounderstand and test a possibility o...

In their article, Doerig et al suggest a set of criteria for evaluating theories of consciousness. Naturally, their criteria are situated in their own particular perspective on consciousness science, which we have critiqued in the past. Their first criterion is likely to be the one that is most productive and least contentious: if the field can agr...

Research on the neural basis of conscious perception has almost exclusively shown that becoming aware of a stimulus leads to increased neural responses. By designing a novel form of perceptual filling-in (PFI) overlaid with a dynamic texture display, we frequency-tagged multiple disappearing targets as well as their surroundings. We show that in a...

Detecting changes in the environment is fundamental for our survival. According to predictive coding theory, detecting these irregularities relies both on incoming sensory information and our top-down prior expectations (or internal generative models) about the world. Prediction errors (PEs), detectable in event-related potentials (ERPs), occur whe...

Our conscious experience of the world seems to go in lockstep with our attentional focus: We tend to see, hear, taste, and feel what we attend to, and vice versa. This tight coupling between attention and consciousness has given rise to the idea that these two phenomena are indivisible. In the late 1950s, the honoree of this special issue, Charles...

When presented with an oscillatory sensory input at a particular frequency, F [Hz], neural systems respond with the corresponding frequency, f [Hz], and its multiples. When the input includes two frequencies ( F1 and F2 ) and they are nonlinearly integrated in the system, responses at intermodulation frequencies (i.e., n1 * f1 + n2 * f2 [Hz], where...

In their article (Doerig et al., 2020), Doerig et al suggest a set of criteria for evaluating theories of consciousness. Naturally, their criteria are situated in their own particular perspective on consciousness science (Doerig et al., 2019), which we have critiqued in the past (Tsuchiya et al., 2020). Their first criterion is likely to be the one...

Attentional lapses are ubiquitous and can negatively impact performance. They correlate with mind wandering, or thoughts that are unrelated to ongoing tasks and environmental demands. In other cases, the stream of consciousness itself comes to a halt and the mind goes blank. What happens in the brain that leads to these mental states? To understand...

The Dream Catcher test defines the criteria for a genuine discovery of the neural constituents of phenomenal consciousness. Passing the test implies that some patterns of purely brain-based data directly correspond to the subjective features of phenomenal experience, which would help to bridge the explanatory gap between consciousness and brain. He...

The content of conscious perception is known to correlate with steady-state responses (SSRs), yet their causal relationship remains unclear. Can we manipulate conscious perception by directly interfering with SSRs through transcranial alternating current stimulation (tACS)? Here, we directly addressed this question in three experiments involving bi...

We showcase an optical phenomenon that we call Third-Eye Rivalry. The effect is most easily induced by viewing one’s own reflection in a mirror. Using the pupil of the opposing eye as a fixation target, people can easily cross their eyes in free fusion to experience vivid rivalry. The resulting percept is of a prominent central “third” eye and two...

Our conscious experience of the world seems to go in lockstep with our attentional focus: we tend to see, hear, taste and feel what we attend to, and vice versa. This tight coupling between attention and consciousness has given rise to the idea that these two phenomena are indivisible. In the late 1950s, the honoree of this special issue, Charles E...

Attentional lapses are ubiquitous and can negatively impact performance. They correlate with mind wandering, or thoughts that are unrelated to ongoing tasks and environmental demands. In other cases, the stream of consciousness itself comes to a halt and the mind goes blank. What happens in the brain that leads to these mental states? To understand...

Team flow occurs when a group of people reaches high task engagement while sharing a common goal as in sports teams and music bands. While team flow is a superior enjoyable experience to individuals experiencing flow or regular socialization, the neural basis for such superiority is still unclear. Here, we addressed this question utilizing a music...

Team flow occurs when a group of people reaches high task engagement while sharing a common goal as in sports teams and music bands. While team flow is a superior enjoyable experience to individuals experiencing flow or regular socialization, the neural basis for such superiority is still unclear. Here, we addressed this question utilizing a music...

Several previous studies have interfered with the observer’s facial mimicry during a variety of facial expression recognition tasks providing evidence in favor of the role of facial mimicry and sensorimotor activity in emotion processing. In this theoretical context, a particularly intriguing facet has been neglected, namely whether blocking facial...

We apply techniques from the field of computational mechanics to evaluate the statistical complexity of neural recording data from fruit flies. First, we connect statistical complexity to the flies' level of conscious arousal, which is manipulated by general anesthesia (isoflurane). We show that the complexity of even single channel time series dat...

The physical basis of consciousness remains one of the most elusive concepts in current science. One influential conjecture is that consciousness is to do with some form of causality, measurable through information. The integrated information theory of consciousness (IIT) proposes that conscious experience, filled with rich and specific content, co...

Evidence accumulation clustering (EAC) is an ensemble clustering algorithm that can cluster data for arbitrary shapes and numbers of clusters. Here, we present a variant of EAC in which we aimed to better cluster data with a large number of features, many of which may be uninformative. Our new method builds on the existing EAC algorithm by populati...

Characterizing consciousness in and of itself is notoriously difficult. Any effort to define consciousness seems to evade what it tries to achieve. In particular, definitions often involve comparisons of different kinds of “consciousness” in a self-referential manner. The tautological nature of characterizing consciousness has led some scholars to...

Although visual awareness of an object typically increases neural responses, we identify a neural response that increases prior to perceptual disappearances , and that scales with the amount of invisibility reported during perceptual filling-in. These findings challenge long-held assumptions regarding the neural correlates of consciousness and entr...

Perceptual filling-in (PFI) occurs when a physically present visual target disappears from conscious perception, with its location filled-in by the surrounding visual background. These perceptual changes are complete, near instantaneous, and can occur for multiple separate locations simultaneously. Here, we show that contrasting neural activity dur...

In our recent essay on Cognitive Science [Naotsugu Tsuchiya & Hayato Saigo (2019) “Understanding Consciousness Through Category Theory” vol 26, pp 462 - 477], we provided a general introduction of category theory to consciousness researchers. Further, we also provided our tentative theoretical sketches on our latest ideas on how to apply tools in c...

Typically, individuals have an attentional bias toward the left visual field. This is often absent in individuals with attention-deficit/hyperactivity (ADH) disorder (ADHD). We used a motion-induced blindness task with targets in 4 quadrants to assess left/right as well as upper/lower spatial biases in perceptual disappearances and also measured ch...

我々が主観的に感じる意識と、脳の中で生じている物理・化学現象の間をつなぐ科学法則とは一体どのようなものだろうか？ 意識をめぐる謎は、現代科学が直面している謎の中でも最も巨大でかつ魅惑的なものの一つである。この謎を避け、人間や動物を外部から観測可能な行動のみから規定しようとする世界観では、幻覚・妄想などを訴える患者の意識の理解、さらには、言語報告のできない患者・乳児・動物の主観感覚の理解といった問題に、科学的なメスを入れることができない。近年、そのような世界観を乗り越え、意識の問題に真っ向から取り込もうとする科学者が中心となり、意識と脳の関係性を巡る実証的研究が大幅に進んできた。本稿では、現状見込みがあると考えられている意識研究のいくつかの研究の枠組みを概観する。さらに、従来の枠組みでは乗り越...

Consciousness is a central issue in neuroscience, however, we still lack a formal framework that can address the nature of the relationship between consciousness and its physical substrates. In this review, we provide a novel mathematical framework of category theory (CT), in which we can define and study the sameness between different domains of p...

Detecting changes in the environment is fundamental for survival, as these may indicate potential rewards or threats. According to predictive coding theory, detecting these irregularities relies on both incoming sensory information and our prior beliefs; with incongruity between the two manifesting as a prediction error (PE) response. Many changes...

Background: Quantifying interactions among many neurons is fundamental to understanding system-level phenomena such as attention, learning and even conscious experience. Causal influences in the brain, quantified as integrated information, are thought to support subjective conscious experience. Recent empirical work has shown that the spectral dec...

The content of conscious perception is known to correlate with steady-state responses (SSRs), yet their causal relationship remains unclear. Can we manipulate conscious perception by directly interfering with SSRs through transcranial alternating current stimulation (tACS)? Here, we directly addressed this question in three experiments involving bi...

We showcase an optical phenomenon that we call “Third-eye Rivalry”. The effect is most easily induced by viewing one’s own reflection in a mirror. Using the pupil of the opposing eye as a fixation target, people can easily cross their eyes in free-fusion to experience vivid rivalry. The resulting percept is of a prominent central “third” eye and tw...

Sleep has been classically described as an all-or-nothing global phenomenon. However, recent research strongly suggests that this view requires tempering. Invasive and non-invasive recordings in animals and humans show that neural activity typically associated with sleep can locally occur during wakefulness. Although local sleep is defined neuronal...

Experience with visual stimuli can improve their perceptual performance, a phenomenon termed visual perceptual learning (VPL). VPL has been found to improve metacognitive measures, suggesting increased conscious accessibility to the knowledge supporting perceptual decision-making. However, such studies have largely failed to control objective task...

Sleep has been classically described as an all-or-nothing global phenomenon. However, recent research has provided strong evidence to suggest that this view requires tempering. Invasive and non-invasive recordings in sleep-deprived animals and humans show that neural activity typically associated with sleep can locally occur during wakefulness. Alt...

Consciousness is a central issue in cognitive neuroscience. To explain the relationship between consciousness and its neural correlates, various theories have been proposed. We still lack a formal framework that can address the nature of the relationship between consciousness and its physical substrates though. Here, we provide a novel mathematical...

In their recent article, the unfolding argument, Doerig et al argue that a theory of consciousness cannot be based in the characterization of the physical structure of the brain. They argue that such theories must be “either false or outside the realm of science”. Instead, they prefer theories of consciousness based only on “input-output” descripti...

We apply techniques from the field of computational mechanics to evaluate the statistical complexity of neural recording data in fruit flies. We connect statistical complexity to the flies' level of conscious arousal, which is manipulated by general anaesthesia (isoflurane). We show that the complexity of even single channel time series data decrea...

The Dream Catcher test defines the criteria for a genuine discovery of the neural constituents of phenomenal consciousness. Passing the test implies that some patterns of purely brain-based data directly correspond to the subjective features of phenomenal experience, which would help to bridge the explanatory gap between consciousness and brain. He...

Quantifying causal influences between elements of a system remains a central topic in many fields of research. In neuroscience, causal influences among neurons, quantified as integrated information, have been suggested to play a critical role in supporting subjective conscious experience. Recent empirical work has shown that the spectral decomposit...