scholarly journals An elasticity-curvature illusion decouples cutaneous and proprioceptive cues in active exploration of soft objects

2021 ◽  
Vol 17 (3) ◽  
pp. e1008848
Author(s):  
Chang Xu ◽  
Yuxiang Wang ◽  
Gregory J. Gerling
Keyword(s):  
Natural World ◽  
Perceptual Cues ◽  
Passive Touch ◽  
Skin Contact ◽  
Soft Objects ◽  
Proprioceptive Inputs ◽  
Sense Of Touch ◽  
Active Exploration ◽  
Exploratory Movements ◽  
Finger Pad

Our sense of touch helps us encounter the richness of our natural world. Across a myriad of contexts and repetitions, we have learned to deploy certain exploratory movements in order to elicit perceptual cues that are salient and efficient. The task of identifying optimal exploration strategies and somatosensory cues that underlie our softness perception remains relevant and incomplete. Leveraging psychophysical evaluations combined with computational finite element modeling of skin contact mechanics, we investigate an illusion phenomenon in exploring softness; where small-compliant and large-stiff spheres are indiscriminable. By modulating contact interactions at the finger pad, we find this elasticity-curvature illusion is observable in passive touch, when the finger is constrained to be stationary and only cutaneous responses from mechanosensitive afferents are perceptible. However, these spheres become readily discriminable when explored volitionally with musculoskeletal proprioception available. We subsequently exploit this phenomenon to dissociate relative contributions from cutaneous and proprioceptive signals in encoding our percept of material softness. Our findings shed light on how we volitionally explore soft objects, i.e., by controlling surface contact force to optimally elicit and integrate proprioceptive inputs amidst indiscriminable cutaneous contact cues. Moreover, in passive touch, e.g., for touch-enabled displays grounded to the finger, we find those spheres are discriminable when rates of change in cutaneous contact are varied between the stimuli, to supplant proprioceptive feedback.

scholarly journals An elasticity-curvature illusion decouples cutaneous and proprioceptive cues in active exploration of soft objects

2020 ◽  
Author(s):  
Chang Xu ◽  
Yuxiang Wang ◽  
Gregory J. Gerling
Keyword(s):  
Computational Modeling ◽  
Natural World ◽  
Perceptual Cues ◽  
Perceptual Illusion ◽  
Skin Deformation ◽  
Soft Objects ◽  
Tactile Illusion ◽  
Sense Of Touch ◽  
Active Exploration ◽  
Exploratory Movements

AbstractOur sense of touch helps us encounter the richness of our natural world. Across a myriad of contexts and repetitions, we have learned to deploy certain exploratory movements in order to elicit perceptual cues that are optimal and efficient. Such cues help us assess an object’s roughness, or stickiness, or as in this case, its softness. Leveraging empirical experiments combined with computational modeling of skin deformation, we develop a perceptual illusion for softness, or compliance, where small-compliant and large-stiff spheres are indiscriminable. The elasticity-curvature illusion, however, becomes readily discriminable when explored volitionally. This tactile illusion is unique because it naturally decouples proprioceptive cues from those involving identical, cutaneous contact attributes. Furthermore, the illusion sheds light into exactly how we explore soft objects, i.e., by volitionally controlling force, to optimally elicit and integrate proprioceptive cues amidst illusory cutaneous contact.

scholarly journals In the Tactile Discrimination of Compliance, Perceptual Cues in Addition to Contact Area Are Required

2018 ◽  
Vol 62 (1) ◽  
pp. 1535-1539 ◽  
Author(s):  
Chang Xu ◽  
Yuxiang Wang ◽  
Steven C. Hauser ◽  
Gregory J. Gerling
Keyword(s):  
Contact Area ◽  
Active Touch ◽  
Applied Force ◽  
Perceptual Cues ◽  
Tactile Discrimination ◽  
Passive Touch ◽  
Contact Areas ◽  
Effective Dynamic ◽  
Soft Objects ◽  
Finger Pad

In our ability to discriminate compliant, or ‘soft,’ objects, we rely upon information acquired from interactions at the finger pad. We have yet to resolve the most pertinent perceptual cues. However, doing so is vital for building effective, dynamic displays. By introducing psychophysical illusions through spheres of various size and elasticity, we investigate the utility of contact area cues, thought to be key in encoding compliance. For both active and passive touch, we determine finger pad-to-stimulus contact areas, using an ink-based procedure, as well as discrimination thresholds. The findings indicate that in passive touch, participants cannot discriminate certain small compliant versus large stiff spheres, which generate similar contact areas. In active touch, however, participants easily discriminate these spheres, though contact areas remain similar. Supplementary cues based on stimulus rate and/or proprioception seem vital. One cue that does differ for illusion cases is finger displacement given a volitionally applied force.

Perceiving Roughness via a Rigid Probe: Effects of Exploration Speed

1999 ◽  
Author(s):  
R. L. Klatzky ◽  
S. J. Lederman ◽  
C. Hamilton ◽  
G. Ramsay
Keyword(s):  
Virtual Environment ◽  
Relative Magnitude ◽  
Fold Change ◽  
Haptic Interfaces ◽  
Textured Surfaces ◽  
Passive Touch ◽  
Global Comparison ◽  
Sense Of Touch ◽  
Active Exploration ◽  
Roughness Perception

Abstract This study investigates the psychophysical consequences for roughness perception of altering the speed with which textured surfaces are explored using a rigid probe. Two ranges of probe speed are used: a 4-fold change (Experiment 1) and a 10-fold change (Experiment 2). The data are examined in terms of the effects of speed upon the psychophysical roughness functions (i.e., perceived roughness as a function of interelement spacing). In addition, we perform a global comparison of the relative magnitude of haptic speed effects across current and previous experiments, using a new measure that we derive here. We discover that roughness constancy declines as the range of speed is reduced, sometimes quite substantially so. The results are considered as well in terms of their implications for producing and exploring simulated textures with haptic interfaces for teleoperation and virtual-environment systems. While we most often touch objects directly with our bare hands, we also frequently use intermediary links such as tools to bring about such interactions. In this paper, we report the results of two psychophysical experiments that extend our recent work (Klatzky & Lederman, 1999; Lederman & Klatzky, 1999) on how people perceive surface roughness via rigid probes. The current experiments investigate the effects of probe speed on roughness perception under active exploration. A more comprehensive paper, which also includes comparable results for passive touch (the surfaces are moved across a stationary probe), has been submitted1. In addition to their contribution to psychophysical issues pertaining to the sense of touch, the results are also relevant to the preparation and exploration of synthetic texture information by means of haptic interfaces for teleoperator and virtual-environment systems.

Friction sensing mechanisms for perception and motor control: Passive touch without sliding may not provide perceivable frictional information

2021 ◽  
Author(s):  
Heba Khamis ◽  
Hafiz Malik Naqash Afzal ◽  
Jennifer Sanchez ◽  
Richard Martin Vickery ◽  
Michael Wiertlewski ◽  
...  
Keyword(s):  
Skin Surface ◽  
Friction Reduction ◽  
Initial Contact ◽  
Textured Surface ◽  
Conscious Perception ◽  
Flat Surfaces ◽  
Passive Touch ◽  
Frictional Properties ◽  
Tangential Forces ◽  
Exploratory Movements

Perception of the frictional properties of a surface contributes to the multidimensional experience of exploring various materials - we slide our fingers over a surface to feel it. In contrast, during object manipulation we grip objects without such intended exploratory movements. Given that we are aware of the slipperiness of objects or tools that are held in the hand, we investigated whether the initial contact between the fingertip skin and the surface of the object is sufficient to provide this consciously perceived frictional information. Using a two-alternative forced choice protocol we examined human capacity to detect frictional differences using touch, when two otherwise structurally identical surfaces were brought in contact with the immobilized finger perpendicularly or under an angle (20 or 30°) to the skin surface (passive touch). An ultrasonic friction reduction device was used to generate three different frictions over each of three flat surfaces with different surface structure: i) smooth glass, ii) textured surface with dome-shaped features, and iii) surface with sharp asperities (sandpaper). Participants (n = 12) could not reliably indicate which of two surfaces was more slippery under any of these conditions. In contrast, when slip was induced by moving the surface laterally by a total of 5 mm (passive slip), participants could clearly perceive frictional differences. Thus making contact with the surface, even with moderate tangential forces, was not enough to perceive frictional differences, instead conscious perception required a sufficient size slip.

Differences in finger skin contact cooling response between an arterial occlusion and a vasodilated condition

2006 ◽  
Vol 100 (5) ◽  
pp. 1596-1601 ◽  
Author(s):  
Ollie Jay ◽  
George Havenith
Keyword(s):  
Blood Flow ◽  
Contact Force ◽  
Arterial Occlusion ◽  
Contact Temperature ◽  
Cooling Curve ◽  
Flow Conditions ◽  
Capillary Perfusion ◽  
Skin Contact ◽  
Finger Skin ◽  
Finger Pad

To assess the presence and magnitude of the effect of skin blood flow on finger skin cooling on contact with cold objects against the background of circulatory disorder risks in occupational exposures, this study investigates the effect of zero vs. close-to-maximal hand blood flow on short-term (≤180 s) skin contact cooling response at a contact pressure that allows capillary perfusion of the distal pulp of the fingertip. Six male volunteers touched a block of aluminium with a finger contact force of 0.5 N at a temperature of −2°C under a vasodilated and an occluded condition. Before both conditions, participants were required to exercise in a hot room for ≥30 min for cutaneous vasodilation to occur (increase in rectal temperature of 1°C). Under the vasodilated condition, forearm blood flow rate rose as high as 16.8 ml·100 ml−1·min−1. Under the occluded condition, the arm was exsanguinated, after which a blood pressure cuff was secured on the wrist inducing arterial occlusion. Contact temperature of the finger pad during the subsequent cold contact exposure was measured. No significant difference was found between the starting skin temperatures for the two blood flow conditions, but a distinct difference in shape of the contact cooling curve was apparent between the two blood flow conditions, with Newtonian cooling observed under the occluded condition, whereas a rewarming of the finger skin toward the end of the exposure occurred for the vasodilated condition. Blood flow was found to significantly increase contact temperature from 40 s onward ( P < 0.01). It is concluded that, at a finger contact force compatible with capillary perfusion of the finger pad (∼0.5 N), circulating blood provides a heat input source that significantly affects finger skin contact cooling during a vasodilated state.

Age-Related Differences in Processing Dynamic Information to Identify Vowel Quality

1992 ◽  
Vol 35 (4) ◽  
pp. 892-902 ◽  
Author(s):  
Robert Allen Fox ◽  
Lida G. Wall ◽  
Jeanne Gokcen
Keyword(s):  
Older Adults ◽  
Vowel Quality ◽  
Perceptual Cues ◽  
Dynamic Information ◽  
Process Dynamic ◽  
Center Condition ◽  
Age Related ◽  
Control Version ◽  
Older Subjects ◽  
Whole Word

This study examined age-related differences in the use of dynamic acoustic information (in the form of formant transitions) to identify vowel quality in CVCs. Two versions of 61 naturally produced, commonly occurring, monosyllabic English words were created: a control version (the unmodified whole word) and a silent-center version (in which approximately 62% of the medial vowel was replaced by silence). A group of normal-hearing young adults (19–25 years old) and older adults (61–75 years old) identified these tokens. The older subjects were found to be significantly worse than the younger subjects at identifying the medial vowel and the initial and final consonants in the silent-center condition. These results support the hypothesis of an age-related decrement in the ability to process dynamic perceptual cues in the perception of vowel quality.

New MRSA Subclone Spread Through Skin Contact

2008 ◽  
Vol 39 (1) ◽  
pp. 35
Author(s):  
PATRICE WENDLING
Keyword(s):  
Skin Contact

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

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