Motor-Sensory Feedback and the Geometry of Visual Space

Held, Richard; Rekosh, Jerold H.

doi:10.1126/science.141.3582.722

Cited by 65 publications

(29 citation statements)

References 6 publications

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“…Clearly, position sense does not rely on proprioceptive information alone, but supplements this with vision (29,30) and efferent copies of motor commands (31). Motor learning might involve correcting a distorted underlying model with these additional inputs, analogous to adaptive changes following exposure to visually distorting prisms (32) or surgical elongation of limbs (33). Our experiments removed these two potentially enriching inputs to the represented body.…”

Section: Discussionmentioning

confidence: 99%

An implicit body representation underlying human position sense

Longo

Haggard

2010

Proc. Natl. Acad. Sci. U.S.A.

323

378

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Knowing the body's location in external space is a fundamental perceptual task. Perceiving the location of body parts through proprioception requires that information about the angles of each joint (i.e., body posture) be combined with information about the size and shape of the body segments between joints. Although information about body posture is specified by on-line afferent signals, no sensory signals are directly informative about body size and shape. Thus, human position sense must refer to a stored body model of the body's metric properties, such as body part size and shape. The need for such a model has long been recognized; however, the properties of this model have never been systematically investigated. We developed a technique to isolate and measure this body model. Participants judged the location in external space of 10 landmarks on the hand. By analyzing the internal configuration of the locations of these points, we produced implicit maps of the mental representation of hand size and shape. We show that this part of the body model is massively distorted, in a reliable and characteristic fashion, featuring shortened fingers and broadened hands. Intriguingly, these distortions appear to retain several characteristics of primary somatosensory representations, such as the Penfield homunculus.body image | proprioception | postural schema | body representation P erceiving the body's location in external space is essential for interacting with our environment and for constructing a coherent sense of self. Proprioceptive signals from afferents in muscles, joints, and skin provide information about joint flexion or extension (1, 2), contributing to a representation of body posture, the postural schema (3). To perceive the absolute position of body parts in external space, however, this postural information must be combined with information about the size and shape of the body segments connecting the joints (4-8) (Fig. 1A). No sensory signal, however, directly informs the brain about the metric properties of body parts. Thus, localization of the body in external space requires that on-line afferent signals specifying joint angles be informed by a stored body model. Although several researchers have identified the need for such a body model (4,6,8), no attempt has been made to measure this model, and its properties are unknown. Here, we systematically investigate the body model mediating position sense of the human hand, showing that it is massively distorted, and appears to retain distortions characteristic of the somatosensory homunculus.The essential contribution of the body model to position sense is specifying the relative locations of body parts. The overall "localization error" for a single landmark (i.e., the distance between actual and judged locations) depends on several factors. In contrast, the distance between the judged locations of two adjacent landmarks (e.g., the tip and knuckle of a single finger) depends only on the represented length of the body segment connecting them. Other sources o...

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Section: Discussionmentioning

confidence: 99%

An implicit body representation underlying human position sense

Longo

Haggard

2010

Proc. Natl. Acad. Sci. U.S.A.

323

378

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“…The task of adjusting the variable curvature square, on the other hand, was almost entirely a visual task requiring no visual-motor coordination. Therefore, the adaptation measures in this experiment consisted almost entirely of visual adaptation, similar to the visual adaptation to curvature distortion produced by prisms in a nonlinear environment reported by Held and Rekosh (1963).…”

Section: Discussionmentioning

confidence: 74%

Perception of, and adaptation to, a three-dimensional curvature distortion

Vernoy

Luria

1977

Perception & Psychophysics

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The curvature distortion perceived under water was measured in three dimensions before and after 15 min of adaptation to the underwater environment. Subjects initially perceived distortions in all three dimensions. After 15 min under water, they exhibited significant adaptation to the curvature distortion in all dimensions. The type of task performed while in the water did not significantly affect the amount of adaptation. The results are compared with those of previous experiments which have reported evidence of counteradaptation when more than one kind of adaptation is measured simultaneously.

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“…Thus, for example, in Held and Rekosh's (1963) previously mentioned study, if, instead of walking around the cylindrical room, the observer was passively wheeled around, no significant change in visual perception of curvature occurred. Another example can be cited from Slotnick's (1969) previously mentioned study.…”

Section: Explanations Of Change In Visual Perceptionmentioning

confidence: 67%

“…The magnitude of this "normalization" effect, however, is small and it cannot account entirely for the amount of perceptual adaptation Pick and Hay reported. Held and Rekosh (1963) report a study that conclusively eliminates the Gibson normalization effect as the sole explanation of such findings. Observers wore 20-diopter monocular prisms, bases mounted laterally, and walked around for one half hour in a darkened cylindrical room, the walls of which were covered with a random array of small luminous spots.…”

Section: Is There Evidence Of Visual Adaptation To Curvature Distortion?mentioning

confidence: 95%