Plasticity in Human Sensorimotor Control

Held, Richard; Freedman, Sanford J.

doi:10.1126/science.142.3591.455

Cited by 312 publications

(173 citation statements)

References 14 publications

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“…In Held's associative memory, exafference must cause a variation in the sensory associates of a given motor signal and hence an increase in the variable error of perception. Held and Freedman (1963) report evidence of this effect of exafference in the adaptation of a perceptual skill different from visual position constancy: eye-hand coordination. The absence of such an effect in the case of visual position constancy (cf.…”

Section: Discussionmentioning

confidence: 99%

Reafference learning in the presence of exafference

Hay

1981

Perception & Psychophysics

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Reafference learning has been demonstrated most clearly in the case of position-eonstancy adaptation in which the only stimulus change is caused by the subject's own movement. The present study used the more ecologically representative training situation in which only part of the stimulus change is caused by the subject (reafference), while part of it is caused by an independent source (exafference). The exafference varied the space relation between subject movement and optical movement or the time relation between those two. In both cases, reafference learning was not affected by the exafference, and the subject's varied training experience resulted in a fixed expected optical movement and a fixed expected time lag.In reafference learning, a person learns to expect a certain stimulus change whenever he makes a certain movement (Held, 1961;Welch, 1978). For example, if the person is trained with a diagonal optical movement paired with vertical head turning, he/she comes to require a portion of that diagonal optical movement for an object to appear stationary during that head movement. This specific phenomenon is called position constancy adaptation and is the best exemplification of reafference learning (Hay, 1968(Hay, , 1974Shebilske, 1977). However, the ecological representativeness of the usual laboratory procedure is doubtful. In the real world, other things besides the observer move, and hence there will be a less than perfect correlation between subject movement and optical movement. Externally caused components of stimulus change are called exafference, in contrast with the subject-caused component called reafference (Holst, 1954). The question of the present study is: What happens to reafference learning when exafference is present, when there is an imperfect correlation between the person's movement and stimulus change?The strategy of this study is to see how two of the known properties of position constancy adaptation change when exafference is present during the training situation. Hay (1968) made such a preliminary investigation. Hay and Goldsmith (1973) have found that the adaptation state has two components: an expected optical motion (EOM) and an expected time lag (ETL) between the head movement and the This research was supported by National Science Foundation Grant GB-33449 to the University of Wisconsin-Milwaukee, with the author as principal investigator. A qualitative summary of the results was given in Hay (1974) and was referred to in Welch (1978). optical movement. We shall therefore introduce exafference into both of the corresponding components of the training situation: the optical-motion component (Experiment 1) and the time-lag component (Experiment 2). EXPERIMENT 1A luminous spot in an otherwise dark room is made to undergo horizontal oscillation when the subject nods his head up and down. The resulting diagonal optical motion (OM) relative to the head constitutes the training reafference. Exafference is added to this in the form of a horizontal, vertical, or combined horizontal-and-...

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Section: Discussionmentioning

confidence: 99%

Reafference learning in the presence of exafference

Hay

1981

Perception & Psychophysics

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“…The classic studies of Held and Hein (1963) showed that kittens that were prevented from actively exploring the visual world, even though they received the same visual stimulation as their normal counterparts, failed to show normal behaviour in many visually guided tasks. In addition, Held's experiments on humans adapting to prismatic distortion of the visual world also demonstrated the importance of motor feedback in maintaining accurate visual coordination (e.g., Held & Freedman, 1963;Held & Hein, 1963). Adaptation to prismatic distortions was much better under conditions of active movement in which visual feedback was dependent on a participant's self-generated activity, than it was under more passive viewing conditions, in which the participant was moved about on a trolley or in a wheelchair (for review see Held, 1965; for critical discussion see Dolezal, 1982).…”

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confidence: 99%

Manipulating and recognizing virtual objects: Where the action is.

James¹,

Humphrey²,

Goodale³

2001

Canadian Journal of Experimental Psychology / Revue canadienne

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In an earlier report (Harman, Humphrey, & Goodale, 1999), we demonstrated that observers who actively rotated three-dimensional novel objects on a computer screen later showed faster visual recognition of these objects than did observers who had passively viewed exactly the same sequence of images of these virtual objects. In Experiment 1 of the present study we showed that compared to passive viewing, active exploration of three-dimensional object structure led to faster performance on a "mental rotation" task involving the studied objects. In addition, we examined how much time observers concentrated on particular views during active exploration. As we found in the previous report, they spent most of their time looking at the "side" and "front" views ("plan" views) of the objects, rather than the three-quarter or intermediate views. This strong preference for the plan views of an object led us to examine the possibility in Experiment 2 that restricting the studied views in active exploration to either the plan views or the intermediate views would result in differential learning. We found that recognition of objects was faster after active exploration limited to plan views than after active exploration of intermediate views. Taken together, these experiments demonstrate (1) that active exploration facilitates learning of the three-dimensional structure of objects, and (2) that the superior performance following active exploration may be a direct result of the opportunity to spend more time on plan views of the object.Résumé Lors d'une étude antérieure (Harman, Humphrey et Goodale, 1999), nous avons démontré que les observateurs qui effectuaient eux-mêmes la rotation d'objets tridimensionnels nouveaux, présentés à l'écran d'un ordinateur, affichaient une reconnaissance visuelle de ces objets plus rapide que ne le faisaient les observateurs qui avaient passivement visionné la même suite d'images illustrant ces objets virtuels. Dans l'expérience 1 de la présente étude, nous avons montré que, par rapport à l'observation passive, l'exploration active de la structure d'un objet tridimension-

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“…Much interest has centered in recent years on the capacity of human beings to adapt both motorically and visually to an optically rearranged visual field (e.g., Held & Freedman, 1963;Kohler, 1964;Harris, 1965). Most commonly, the distortion has entailed 11·15 deg of lateral displacement, effected by means of wedge prisms.…”

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confidence: 99%

The effect of experienced limb identity upon adaptation to simulated displacement of the visual field

Welch

1972

Perception & Psychophysics

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The effect of experienced limb identity upon adaptation to simulated displacement of the visual field* Ss were confronted with a situation which mimicked the visuomotor consequences of an ll-deg lateral displacement of the visual field (leftward in Experiment I and rightward in Experiment II). The displacement was effected by having E place his own finger to one side of 8's nonvisible f"mger. Ss who were informed of this deception prior to the exposure period (informed group) manifested significantly less adaptation ("negative aftereffect" and "proprioceptive shift") than did Ss who were told that their vision would be displaced by the goggles which they were wearing (misinformed group). It was concluded that adaptation to visual rearrangement is strongly influenced by 8's assumptions regarding the adequacy of his vision and the identity of the manual limb which he is viewing.

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Plasticity in Human Sensorimotor Control

Cited by 312 publications

References 14 publications

Reafference learning in the presence of exafference

Reafference learning in the presence of exafference

Manipulating and recognizing virtual objects: Where the action is.

The effect of experienced limb identity upon adaptation to simulated displacement of the visual field

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