Informative neural representations of unseen contents during higher-order processing in human brains and deep artificial networks

Mei, Ning; Santana, Roberto; Soto, David

doi:10.1038/s41562-021-01274-7

Cited by 17 publications

(10 citation statements)

References 105 publications

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“…However, while higher ventral brain regions also contain representations of invisible complex visual objects [9], fine-grained activity patterns within those regions differ between visible and invisible stimuli [10]. While some studies suggested higher visual cortex shares some representation between visible and invisible stimuli [10,11], unlike our experiments these studies used intact, complex images that did not explicitly require perceptual integration. These experiments therefore cannot rule out that neurons in higher category-selective regions merely respond to the presence of local features related to their preferred category.…”

Section: Discussionmentioning

confidence: 99%

“…Ample evidence shows that some processing of visual objects occurs unconsciously [8]. Invisible stimuli activate higher object-selective brain areas [9][10][11] but responses are more variable [12,13] than during conscious perception. Activity patterns in ventral visual cortex measured while participants view complex images differ between visible and invisible stimuli [10].…”

Section: Introductionmentioning

confidence: 99%

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The role of awareness in shaping responses in human visual cortex

et al. 2023

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The visual cortex contains information about stimuli even when they are not consciously perceived. However, it remains unknown whether the visual system integrates local features into global objects without awareness. Here, we tested this by measuring brain activity in human observers viewing fragmented shapes that were either visible or rendered invisible by fast counterphase flicker. We then projected measured neural responses to these stimuli back into visual space. Visible stimuli caused robust responses reflecting the positions of their component fragments. Their neural representations also strongly resembled one another regardless of local features. By contrast, representations of invisible stimuli differed from one another and, crucially, also from visible stimuli. Our results demonstrate that even the early visual cortex encodes unconscious visual information differently from conscious information, presumably by only encoding local features. This could explain previous conflicting behavioural findings on unconscious visual processing.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The role of awareness in shaping responses in human visual cortex

et al. 2023

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“…Additional details can be found in Mei et al (2022). (Mei et al, 2022b) Figure 1: Experimental paradigm. Example of the sequence of events within an experimental trial.…”

Section: Experimental Paradigmmentioning

confidence: 99%

“…Here we re-analysed fMRI data from a previous study (Mei et al, 2022b) in which participants (N = 7) underwent six fMRI sessions across six days while performing a discrimination task for animate and inanimate images presented very briefly and masked. In addition to multi-voxel pattern classification, we used model-based representational similarity analysis (RSA) to provide a fine-grained information-based approach to the neural representation of unconscious and conscious contents.…”

Section: Introductionmentioning

confidence: 99%

Brain representation in conscious and unconscious vision

Mei,

Soto

2024

Preprint

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The development of robust frameworks to understand how the human brain represents conscious and unconscious perceptual contents is paramount to make progress in the neuroscience of consciousness. Recent functional MRI studies using multi-voxel pattern classification analyses showed that unconscious contents could be decoded from brain activity patterns. However, decoding does not imply a full understanding of neural representations. Here we re-analysed data from a high-precision fMRI study coupled with representational similarity analysis based on convolutional neural network models to provide a detailed information-based approach to neural representations of both unconscious and conscious perceptual content. The results showed that computer vision model representations strongly predicted brain responses in ventral visual cortex and in fronto-parietal regions to both conscious and unconscious contents. Moreover, this pattern of results generalised when the models were trained and tested with different participants. Remarkably, these observations results held even when the analysis was restricted to observers that showed null perceptual sensitivity. In light of the highly distributed brain representation of unconscious information, we suggest that the functional role of fronto-parietal cortex in conscious perception is unlikely to be related to the broadcasting of information, as proposed by the global neuronal workspace theory, and may instead relate to the generation of meta-representations as proposed by higher-order theories.

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“…Although objective measures seem to align best with a scientific approach to consciousness (18, replicable, objective, e.g. see 19), they do require one to invoke a "Gold Standard of seeing" that in fact does not exist (20). Relatedly, they ignore the fact that subjective experience is central to the very definition of consciousness.…”

Section: Introductionmentioning

confidence: 99%

Criterion placement threatens the construct validity of neural measures of consciousness

Fahrenfort,

Johnson,

Kloosterman

et al. 2024

Preprint

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How consciousness arises from brain activity has been a topic of intense scientific research for decades. But how does one identify the neural basis of something that is intrinsically personal and subjective? A hallmark approach has been to ask observers to judge stimuli as 'seen' (conscious) and 'unseen' (unconscious) and use post hoc sorting of neural measurements based these judgments. Unfortunately, cognitive and response biases are known to strongly affect how observers place their criterion for judging stimuli as 'seen' vs. 'unseen', thereby confounding neural measures of consciousness. Astoundingly however, the effect of conservative and liberal criterion placement on neural measures of unconscious and conscious processing has never been explicitly investigated. Here we use simulations and electrophysiological brain measurements to show that conservative criterion placement has an unintuitive consequence: rather than selectively providing a cautious estimate of conscious processing, it inflates effect sizes in neural measures of both conscious and unconscious processing, while liberal criterion placement does the reverse. After showing this in simulation, we performed decoding analyses on two electroencephalography studies that employ common subjective indicators of conscious awareness, in which we experimentally manipulated the response criterion. The results confirm that the predicted confounding effects of criterion placement on neural measures of unconscious and conscious processing occur in empirical data, while further showing that the most widely used subjective scale, the Perceptual Awareness Scale (PAS), does not guard against criterion confounds. Follow up simulations explicate how the experimental context determines whether the relative confounding effect of criterion placement is larger in neural measures of either conscious or unconscious processing. We conclude that criterion placement threatens the construct validity of neural measures of conscious and unconscious processing.

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Informative neural representations of unseen contents during higher-order processing in human brains and deep artificial networks

Cited by 17 publications

References 105 publications

The role of awareness in shaping responses in human visual cortex

The role of awareness in shaping responses in human visual cortex

Brain representation in conscious and unconscious vision

Criterion placement threatens the construct validity of neural measures of consciousness

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