Neuroscience of Consciousness
January 1, 2018
Tim Bayne
The integrated information theory (IIT) is a prominent scientific framework for studying consciousness and developing a consciousness meter. This paper critically examines the axiomatic method that IIT's creators use. The author argues that the method is open to multiple interpretations and that none of IIT's five alleged axioms can play the required role: each either fails to be truly axiomatic or fails to impose a substantive constraint on a theory of consciousness. The article concludes by outlining an alternative methodology for the science of consciousness, called the natural kind approach.
Neuroscience of Consciousness
September 6, 2017
Megan A. K. Peters, Robert W. Kentridge, I. Phillips et al.
The authors present a symposium discussion on whether unconscious perception truly exists, highlighting disagreement on definitions and empirical methods for determining unconscious states. They argue that the controversy hinges on what is meant by key terms and how to measure unconsciousness. The piece is organized into four distinct contributions to reflect the range of ideas and evidence on this topic, aiming to foster consensus among consciousness researchers.
Neuroscience of Consciousness
January 1, 2017
Stephan Krohn, Dirk Ostwald
Integrated information theory (IIT) proposes that consciousness is identical to maximally integrated conceptual information, measured by Φmax, and that experience corresponds to a set of maximally irreducible cause-effect repertoires. This work reformulates IIT in the language of probabilistic models, where a system's dynamics are described by a first-order time-invariant Markov process. The authors provide a constructive rule for decomposing a system into subsystems based on marginalization and factorization of the joint probability distribution over two adjacent time points.
Neuroscience of Consciousness
January 1, 2017
Satohiro Tajima, Ryota Kanai
The integrated information theory (IIT) of consciousness proposes that consciousness corresponds to integrated information within neuronal dynamics, but testing this theory empirically is difficult because it requires observing all elements of a neural system simultaneously. This paper suggests that the topological dimensionality of shared attractor dynamics can serve as an indicator of integrated information in continuous attractor dynamics. Using delay embedding, effects of unobserved nodes can be reconstructed from partial observations, allowing identification of the embedded attractor's dimensionality. The topological dimensionality is invariant to coordinate transformations and thus represents a critical property of integrated information. This approach extends IIT to continuous dynamical systems and relaxes the conditions needed to evaluate integrated information in real neural systems, offering a framework for testing the theory with experimental data.
Neuroscience of Consciousness
May 9, 2016
C. Pfeiffer, Petr Grivaz, B. Herbelin et al.
The direction of a person's first-person perspective—the sense of where one experiences the world from—can be altered by conflicting multisensory cues about gravity. In healthy volunteers lying on their backs, visual motion of objects either toward or away from the body, combined with touch and vestibular signals, shifted the experienced direction of perspective. When visual motion was directed away from the body, participants more often reported a downward-directed perspective, contradicting their actual body orientation. These shifts correlated with changes in self-location, showing that visual gravitational cues help define the subjective viewpoint from which people perceive the world.
Neuroscience of Consciousness
January 1, 2016
Megan A. K. Peters, T. Ro, Hakwan Lau
Response bias can contaminate studies of consciousness when observers report not seeing a stimulus not because they lack subjective experience but because they compare it to other stimuli. While bias-free signal detection measures help avoid this confound, an overemphasis on eliminating criterion effects can mislead research. The authors argue that Balsdon and Azzopardi mistakenly criticized a previous report of 'relative blindsight' for response bias, when the original study never intended to use their bias-removal methods. Dismissing findings solely because they depend on criterion is problematic, as many real effects necessarily involve criterion. The authors conclude that criterion effects are conceptually important in conscious awareness research and should be treated carefully, not avoided thoughtlessly.
Neuroscience of Consciousness
January 1, 2016
Jaan Aru, Renate Rutiku, Michael Wibral et al.
Prior knowledge influences conscious perception very early, within 80-95 milliseconds after a stimulus appears, as shown by magnetoencephalography (MEG) recordings. The effect originates in occipital and posterior parietal brain regions. These findings support predictive coding theories, which propose that prior knowledge rapidly and directly shapes perceptual experience.
Neuroscience of Consciousness
January 1, 2015
Henry Railo, A. Revonsuo, M. Koivisto
People can report whether they consciously saw a visual stimulus in just over 200 milliseconds, and these reports are extremely reliable and not reflexive or unconscious. The neural events that cause conscious vision must happen before these reports. Late cortical processing in the fronto-parietal global neuronal workspace, which occurs around 300 milliseconds, starts after the fastest consciousness reports, so this late activity cannot directly reflect the emergence of visual consciousness. Instead, a negative amplitude difference spreading from occipital to frontal cortex around 160–220 milliseconds precedes the reports, suggesting this neural correlate underlies the emergence of conscious vision.