Weak spatial constancy in touch

Wexler, Mark; Hayward, Vincent

doi:10.1109/whc.2011.5945554

Cited by 7 publications

(4 citation statements)

References 8 publications

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“…Estimating motion of external objects often requires taking into account movements of the sensor (eye or hand motion) and the relative motion of the object with respect the sensory surface (retinal or tactile slip). The two senses have weak spatial constancy, because combining relative and sensor motion leads to inaccurate estimates of object motion (Freeman and Banks 1998;Ziat et al 2010;Wexler and Hayward 2011;Moscatelli et al 2015). Accordingly, in a previous paper we showed a systematic error in the perceived direction of a movable texture in touch, akin to the Filehne illusion in vision (Moscatelli et al 2015).…”

Section: Discussionmentioning

confidence: 79%

Illusory changes in the perceived speed of motion derived from proprioception and touch

Moscatelli

Ernst

2019

Journal of Neurophysiology

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In vision, the perceived velocity of a moving stimulus differs depending on whether we pursue it with the eyes or not: A stimulus moving across the retina with the eyes stationary is perceived as being faster compared with a stimulus of the same physical speed that the observer pursues with the eyes, while its retinal motion is zero. This effect is known as the Aubert–Fleischl phenomenon. Here, we describe an analog phenomenon in touch. We asked participants to estimate the speed of a moving stimulus either from tactile motion only (i.e., motion across the skin), while keeping the hand world stationary, or from kinesthesia only by tracking the stimulus with a guided arm movement, such that the tactile motion on the finger was zero (i.e., only finger motion but no movement across the skin). Participants overestimated the velocity of the stimulus determined from tactile motion compared with kinesthesia in analogy with the visual Aubert–Fleischl phenomenon. In two follow-up experiments, we manipulated the stimulus noise by changing the texture of the touched surface. Similarly to the visual phenomenon, this significantly affected the strength of the illusion. This study supports the hypothesis of shared computations for motion processing between vision and touch. NEW & NOTEWORTHY In vision, the perceived velocity of a moving stimulus is different depending on whether we pursue it with the eyes or not, an effect known as the Aubert–Fleischl phenomenon. We describe an analog phenomenon in touch. We asked participants to estimate the speed of a moving stimulus either from tactile motion or by pursuing it with the hand. Participants overestimated the stimulus velocity measured from tactile motion compared with kinesthesia, in analogy with the visual Aubert–Fleischl phenomenon.

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Section: Discussionmentioning

confidence: 79%

Illusory changes in the perceived speed of motion derived from proprioception and touch

Moscatelli

Ernst

2019

Journal of Neurophysiology

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“…In conclusion, touch—like vision—shows rather poor spatial constancy 29 30 , leading to motion illusions during active hand movement, akin to the Filehne illusion. Motion processing shows other remarkable analogies between vision and touch.…”

Section: Discussionmentioning

confidence: 93%

Illusory Tactile Motion Perception: An Analog of the Visual Filehne Illusion

Moscatelli¹,

Hayward²,

Wexler³

et al. 2015

Sci Rep

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We continually move our body and our eyes when exploring the world, causing our sensory surfaces, the skin and the retina, to move relative to external objects. In order to estimate object motion consistently, an ideal observer would transform estimates of motion acquired from the sensory surface into fixed, world-centered estimates, by taking the motion of the sensor into account. This ability is referred to as spatial constancy. Human vision does not follow this rule strictly and is therefore subject to perceptual illusions during eye movements, where immobile objects can appear to move. Here, we investigated whether one of these, the Filehne illusion, had a counterpart in touch. To this end, observers estimated the movement of a surface from tactile slip, with a moving or with a stationary finger. We found the perceived movement of the surface to be biased if the surface was sensed while moving. This effect exemplifies a failure of spatial constancy that is similar to the Filehne illusion in vision. We quantified this illusion by using a Bayesian model with a prior for stationarity, applied previously in vision. The analogy between vision and touch points to a modality-independent solution to the spatial constancy problem.

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“…Ambiguities arise in the dynamics of wielded objects [38], but other types of ambiguities can be created by introducing symmetries in low-dimensional projections of the plenhaptic function, as in earlier studies [39,40], or from the basic laws of mechanics [34]. By the same token, a single, isolated moving object can create very different projections of the plenhaptic function [41].…”

Section: Discussionmentioning

confidence: 99%

Is there a ‘plenhaptic’ function?

Hayward

2011

Phil. Trans. R. Soc. B

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One approach to gauge the complexity of the computational problem underlying haptic perception is to determine the number of dimensions needed to describe it. In vision, the number of dimensions can be estimated to be seven. This observation raises the question of what is the number of dimensions needed to describe touch. Only with certain simplified representations of mechanical interactions can this number be estimated, because it is in general infinite. Organisms must be sensitive to considerably reduced subsets of all possible measurements. These reductions are discussed by considering the sensing apparatuses of some animals and the underlying mechanisms of two haptic illusions.

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Weak spatial constancy in touch

Cited by 7 publications

References 8 publications

Illusory changes in the perceived speed of motion derived from proprioception and touch

Illusory changes in the perceived speed of motion derived from proprioception and touch

Illusory Tactile Motion Perception: An Analog of the Visual Filehne Illusion

Is there a ‘plenhaptic’ function?

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