Prior knowledge biases the visual memory of body postures

Han, Qiu; Gandolfo, Marco; Peelen, Marius V.

doi:10.1016/j.isci.2024.109475

Cited by 4 publications

(1 citation statement)

References 57 publications

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“…The configuration of the Cartesian priors varied across participants, though they tended to cluster near a more extended or flexed finger posture ( Figure 3C ). These extremes are common resting hand postures, suggesting that the Cartesian prior may reflect the accumulated history of previous finger configurations, built upon sensorimotor 35–37 and visual 38 feedback. Investigating the statistics of natural everyday finger postures would be one way address the origin of these priors.…”

Section: Discussionmentioning

confidence: 99%

Biases in hand perception are driven by somatosensory computations, not a distorted hand model

Peviani,

Miller,

Medendorp

2023

Preprint

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SummaryTo sense and interact with objects in the environment, we effortlessly configure our fingertips at desired locations. It is therefore reasonable to assume the underlying control mechanisms rely on accurate knowledge about the structure and spatial dimensions of our hand and fingers. This intuition, however, is challenged by years of research showing drastic biases in the perception of finger geometry, e.g.,1–5. This perceptual bias has been taken as evidence that the brain’s internal representation of the body’s geometry is distorted,6leading to an apparent paradox with the skillfulness of our actions.7Here, we propose an alternative explanation of the biases in hand perception—They are the result of the Bayesian integration of noisy, but unbiased somatosensory signals about finger geometry and posture. To address this hypothesis, we combined Bayesian reverse-engineering with behavioral experimentation on joint and fingertip localization of the index finger. We modelled the Bayesian integration either in sensory or in space-based coordinates, showing that the latter model variant led to biases in finger perception despiteaccuraterepresentations of finger length. Behavioral measures of joint and fingertip localization responses showed similar biases, which were well-fitted by the space-based but not the sensory-based model variant. Our results suggest that perceptual distortions of finger geometry do not reflect a distorted hand model but originate from near-optimal Bayesian inference on somatosensory signals. These findings demand a reinterpretation of previous work on hand model distortions.

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Section: Discussionmentioning

confidence: 99%

Biases in hand perception are driven by somatosensory computations, not a distorted hand model

Peviani,

Miller,

Medendorp

2023

Preprint

View full text Add to dashboard Cite

show abstract

Biases in hand perception are driven by somatosensory computations, not a distorted hand model

Peviani,

Miller,

Medendorp

2024

Current Biology

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Boosting forward connectivity between primary visual and body selective cortex reduces interference of task irrelevant dimensions on body judgements

Gandolfo,

D’Argenio,

Downing

et al. 2024

Preprint

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We effortlessly categorise other people along socially relevant categories such as sex, age, and emotion. A core question in social vision relates to whether we perceive these categories independently or in relation to each other. Here, we investigated categorisation of sex and emotion from the body, finding that participants generally fail to fully ignore task-irrelevant variations of sex while judging body emotional expressions. In contrast, sex categorisation was unaffected by variations in emotional expression. We propose that this asymmetric interaction between sex and emotion may arise because of bottom-up visual processing, due to partially shared visual features used for both judgments, or because of top-down, categorical associations between sex and emotion categories. To disentangle these possibilities, we used cortico-cortical paired associative stimulation (ccPAS) to modulate the connectivity between primary visual cortex and the extrastriate body area. We posited that boosting forward connectivity between these regions would increase efficiency of feature-based processing, while boosting feedback connectivity would enhance the separability of semantic categories related to sex and emotion. We found that boosting forward connectivity eliminated the interference of the irrelevant variation of body sex on body emotion judgments, while the same interference remained unaffected with modulation of feedback connectivity. These findings suggest that interactions between sex and emotion in body perception emerge during the perceptual analysis of the stimuli, and add to our understanding of person perception and social categorization.

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Prior knowledge biases the visual memory of body postures

Cited by 4 publications

References 57 publications

Biases in hand perception are driven by somatosensory computations, not a distorted hand model

Biases in hand perception are driven by somatosensory computations, not a distorted hand model

Biases in hand perception are driven by somatosensory computations, not a distorted hand model

Boosting forward connectivity between primary visual and body selective cortex reduces interference of task irrelevant dimensions on body judgements

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