Mental body representations retain homuncular shape distortions: Evidence from Weber’s illusion

Miller, Luke; Longo, Matthew R.; Saygın, Ayşe Pınar

doi:10.1016/j.concog.2015.12.008

Cited by 39 publications

(61 citation statements)

References 37 publications

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“…For example, Weber (1834Weber ( /1996 found that the perceived distance between two points of a compass changed as he moved them across his skin, feeling farther apart on regions of high tactile sensitivity compared to regions of lower sensitivity. Subsequent studies have replicated this pattern and suggest a systematic relation between perceived tactile distance and the spatial sensitivity of skin surfaces (e.g., Cholewiak, 1999;Taylor-Clarke et al, 2004;Anema, Wolswijk, Ruis, & Dijkerman, 2008;Miller, Longo, & Saygin, 2016), an effect known as Weber's illusion, suggesting that tactile distance perception preserves spatial distortions characteristic of the famous 'Penfield homunculus' (Penfield & Boldrey, 1937).…”

Section: Distortions Of Tactile Distance Perceptionmentioning

confidence: 88%

Mapping the internal geometry of tactile space.

Longo¹,

Голубова²

2017

Journal of Experimental Psychology: Human Perception and Perfor

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A large body of research has shown spatial distortions in the perception of tactile distances on the skin. For example, perceived tactile distance is increased on sensitive compared to less sensitive skin regions, and larger for stimuli oriented along the medio-lateral axis than the proximo-distal axis of the limbs. In this study we aimed to investigate the spatial coherence of these distortions by reconstructing the internal geometry of tactile space using multidimensional scaling (MDS). Participants made verbal estimates of the perceived distance between 2 touches applied sequentially to locations on their left hand. In Experiment 1 we constructed perceptual maps of the dorsum of the left hand, which showed a good fit to the actual configuration of stimulus locations. Critically, these maps also showed clear evidence of spatial distortion, being stretched along the medio-lateral hand axis. Experiment 2 replicated this result and showed that no such distortion is apparent on the palmar surface of the hand. These results show that distortions in perceived tactile distance can be characterized by geometrically simple and coherent deformations of tactile space. We suggest that the internal geometry of tactile space is shaped by the geometry of receptive fields in somatosensory cortex.

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Section: Distortions Of Tactile Distance Perceptionmentioning

confidence: 88%

Mapping the internal geometry of tactile space.

Longo¹,

Голубова²

2017

Journal of Experimental Psychology: Human Perception and Perfor

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“…In the case of tactile distance perception, however, there is also evidence that this perceptual anisotropy is even bigger on the forearm than on the hand (Le Cornu Knight et al, 2014; Miller et al, 2016). The current study did not find any evidence for differences between these body parts, with quite similar distortions apparent in both cases.…”

Section: Discussionmentioning

confidence: 99%

Expansion of Perceptual Body Maps Near – But Not Across – The Wrist

Longo

2017

Front. Hum. Neurosci.

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Perceiving the external spatial location of touch requires that tactile information about the stimulus location on the skin be integrated with proprioceptive information about the location of the body in external space, a process called tactile spatial remapping. Recent results have suggested that this process relies on a distorted representation of the hand. Here, I investigated whether similar distortions are also found on the forearm and how they are affected by the presence of the wrist joint, which forms a categorical, segmental boundary between the hand and the arm. Participants used a baton to judge the perceived location of touches applied to their left hand or forearm. Similar distortions were apparent on both body parts, with overestimation of distances in the medio-lateral axis compared to the proximo-distal axis. There was no perceptual expansion of distances that crossed the wrist boundary. However, there was increased overestimation of distances near the wrist in the medio-lateral orientation. These results replicate recent findings of a distorted representation of the hand underlying tactile spatial remapping, and show that this effect is not idiosyncratic to the hand, but also affects the forearm. These distortions may be a general characteristic of the mental representation of the arms.

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“…For example, Weber (1834/1996) in his classic studies on touch found that as he moved the two points of a compass across his skin, it felt like the distance between the two points increased as he moved them from a region or relatively low spatial sensitivity (e.g., the upper arm) to a region of higher sensitivity (e.g., the palm). Subsequent studies have replicated this general pattern, showing that perceived tactile distances appear to be systematically related to the sensitivity of different skin surfaces (e.g., Goudge, 1918; Marks et al, 1982; Cholewiak, 1999; Taylor-Clarke et al, 2004; Anema et al, 2008; Miller et al, 2016). Similarly, large anisotropies of perceived tactile distance have been reported on the limbs, with stimuli oriented across the width of limbs being perceived as substantially farther apart than stimuli oriented along the length of the limbs (Green, 1982; Longo and Haggard, 2011; Canzoneri et al, 2013; Longo and Sadibolova, 2013; Le Cornu Knight et al, 2014; Miller et al, 2014, 2016; Longo, 2015).…”

Section: Introductionmentioning

confidence: 88%

No Correlation between Distorted Body Representations Underlying Tactile Distance Perception and Position Sense

Longo

Morcom

2016

Front. Hum. Neurosci.

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Both tactile distance perception and position sense are believed to require that immediate afferent signals be referenced to a stored representation of body size and shape (the body model). For both of these abilities, recent studies have reported that the stored body representations involved are highly distorted, at least in the case of the hand, with the hand dorsum represented as wider and squatter than it actually is. Here, we investigated whether individual differences in the magnitude of these distortions are shared between tactile distance perception and position sense, as would be predicted by the hypothesis that a single distorted body model underlies both tasks. We used established tasks to measure distortions of the represented shape of the hand dorsum. Consistent with previous results, in both cases there were clear biases to overestimate distances oriented along the medio-lateral axis of the hand compared to the proximo-distal axis. Moreover, within each task there were clear split-half correlations, demonstrating that both tasks show consistent individual differences. Critically, however, there was no correlation between the magnitudes of distortion in the two tasks. This casts doubt on the proposal that a common body model underlies both tactile distance perception and position sense.

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Mental body representations retain homuncular shape distortions: Evidence from Weber’s illusion

Cited by 39 publications

References 37 publications

Mapping the internal geometry of tactile space.

Mapping the internal geometry of tactile space.

Expansion of Perceptual Body Maps Near – But Not Across – The Wrist

No Correlation between Distorted Body Representations Underlying Tactile Distance Perception and Position Sense

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