scholarly journals Initial contact shapes the perception of friction

2021 ◽  
Author(s):  
Laurence Willemet ◽  
Khoubeib Kanzari ◽  
Jocelyn Monnoyer ◽  
Ingvars Birznieks ◽  
Michael Wiertlewski
Keyword(s):  
Grip Force ◽  
Radial Strain ◽  
Initial Contact ◽  
Conscious Perception ◽  
Tactile Information ◽  
Skin Deformation ◽  
Frictional Properties ◽  
Frictional Strength ◽  
Tactile Cues ◽  
Perceptual Mechanism

Humans efficiently estimate the grip force necessary to lift a variety of objects, including slippery ones. The regulation of grip force starts with the initial contact, and takes into account the surface properties, such as friction. This estimation of the frictional strength has been shown to depend critically on cutaneous information. However, the physical and perceptual mechanism that provides such early tactile information remains elusive. In this study, we developed a friction-modulation apparatus to elucidate the effects of the frictional properties of objects during initial contact. We found a correlation between participants' conscious perception of friction and radial strain patterns of skin deformation. The results provide insights into the tactile cues made available by contact mechanics to the sensorimotor regulation of grip, as well as to the conscious perception of the frictional properties of an object.

scholarly journals Initial contact shapes the perception of friction

2021 ◽  
Vol 118 (49) ◽  
pp. e2109109118
Author(s):  
Laurence Willemet ◽  
Khoubeib Kanzari ◽  
Jocelyn Monnoyer ◽  
Ingvars Birznieks ◽  
Michaël Wiertlewski
Keyword(s):  
Grip Force ◽  
Radial Strain ◽  
Initial Contact ◽  
Conscious Perception ◽  
Tactile Information ◽  
Skin Deformation ◽  
Frictional Properties ◽  
Frictional Strength ◽  
Tactile Cues ◽  
Perceptual Mechanism

Humans efficiently estimate the grip force necessary to lift a variety of objects, including slippery ones. The regulation of grip force starts with the initial contact and takes into account the surface properties, such as friction. This estimation of the frictional strength has been shown to depend critically on cutaneous information. However, the physical and perceptual mechanism that provides such early tactile information remains elusive. In this study, we developed a friction-modulation apparatus to elucidate the effects of the frictional properties of objects during initial contact. We found a correlation between participants’ conscious perception of friction and radial strain patterns of skin deformation. The results provide insights into the tactile cues made available by contact mechanics to the sensorimotor regulation of grip, as well as to the conscious perception of the frictional properties of an object.

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.

scholarly journals Vision, touch and object manipulation in Senegal parrots Poicephalus senegalus

2011 ◽  
Vol 278 (1725) ◽  
pp. 3687-3693 ◽  
Author(s):  
Zoe P. Demery ◽  
Jackie Chappell ◽  
Graham R. Martin
Keyword(s):  
Visual Fields ◽  
Bird Species ◽  
Object Manipulation ◽  
Field Configuration ◽  
Tactile Information ◽  
Binocular Field ◽  
Prime Determinant ◽  
Tactile Cues ◽  
Foraging Method ◽  
Visual Coverage

Parrots are exceptional among birds for their high levels of exploratory behaviour and manipulatory abilities. It has been argued that foraging method is the prime determinant of a bird's visual field configuration. However, here we argue that the topography of visual fields in parrots is related to their playful dexterity, unique anatomy and particularly the tactile information that is gained through their bill tip organ during object manipulation. We measured the visual fields of Senegal parrots Poicephalus senegalus using the ophthalmoscopic reflex technique and also report some preliminary observations on the bill tip organ in this species. We found that the visual fields of Senegal parrots are unlike those described hitherto in any other bird species, with both a relatively broad frontal binocular field and a near comprehensive field of view around the head. The behavioural implications are discussed and we consider how extractive foraging and object exploration, mediated in part by tactile cues from the bill, has led to the absence of visual coverage of the region below the bill in favour of more comprehensive visual coverage above the head.

Importance of Cutaneous Feedback in Maintaining a Secure Grip During Manipulation of Hand-Held Objects

2003 ◽  
Vol 89 (2) ◽  
pp. 665-671 ◽  
Author(s):  
Anne-Sophie Augurelle ◽  
Allan M. Smith ◽  
Thierry Lejeune ◽  
Jean-Louis Thonnard
Keyword(s):  
Internal Model ◽  
Grip Force ◽  
Tangential Force ◽  
Safety Margin ◽  
Background Level ◽  
Load Force ◽  
Initial Contact ◽  
Phase Lag ◽  
Cutaneous Sensation ◽  
Hold Period

Previous research has shown that grip and load forces are modulated simultaneously during manipulation of a hand-held object. This close temporal coupling suggested that both forces are controlled by an internal model within the CNS that predicts the changes in tangential force on the fingers. The objective of the present study was to examine how the internal model would compensate for the loss of cutaneous sensation through local anesthesia of the index and thumb. Ten healthy adult subjects (5 men and 5 women aged 20–57 yr) were asked to grasp, lift, and hold stationary, a 250 g object for 20 s. Next, the subjects were asked to perform vertical oscillatory movements over a distance of 20 cm at a rate of 1.0 Hz for 30 s. Eleven trials were performed with intact sensation, and 11 trials after a local ring-block anesthesia of the index and thumb with bupivacain (5 mg/ml). During static holding, loss of cutaneous sensation produced a significant increase in the safety margin. However, the grip force declined significantly over the 20-s static hold period. During oscillatory arm movements, grip and load forces were continuously modulated together in a predictive manner as suggested by Flanagan and Wing. Again, the grip force declined over the 30-s movement, and 7/10 subjects dropped the object at least once. With intact sensation, the object was never dropped; but with the fingers anesthetized, it was dropped on 36% of the trials, and a significant slip occurred on a further 12%. The mean correlation between the grip and load forces for all subjects deteriorated from 0.71 with intact sensation to 0.48 after digital anesthesia. However, a cross-correlation calculated between the grip and load forces indicated that the phase lag was approximately zero both with and without digital anesthesia. Taken together, the data from the present study suggest that cutaneous afferents are required for setting and maintaining the background level of the grip force in addition to their phasic slip-detection function and their role in adapting the grip force/load force ratio to the friction on initial contact with an object. Finally, at a more theoretical level, they correct and maintain an internal model of the physical properties of hand-held objects.

scholarly journals The role of vibration in tactile speed perception

2015 ◽  
Vol 114 (6) ◽  
pp. 3131-3139 ◽  
Author(s):  
Chris J. Dallmann ◽  
Marc O. Ernst ◽  
Alessandro Moscatelli
Keyword(s):  
Relative Motion ◽  
High Frequency ◽  
Low Frequency ◽  
Skin Deformation ◽  
Tactile Cues ◽  
Speed Perception ◽  
High Frequency Vibrations ◽  
Speed Discrimination ◽  
Slip Motion

The relative motion between the surface of an object and our fingers produces patterns of skin deformation such as stretch, indentation, and vibrations. In this study, we hypothesized that motion-induced vibrations are combined with other tactile cues for the discrimination of tactile speed. Specifically, we hypothesized that vibrations provide a critical cue to tactile speed on surfaces lacking individually detectable features like dots or ridges. Thus masking vibrations unrelated to slip motion should impair the discriminability of tactile speed, and the effect should be surface-dependent. To test this hypothesis, we measured the precision of participants in discriminating the speed of moving surfaces having either a fine or a ridged texture, while adding masking vibratory noise in the working range of the fast-adapting mechanoreceptive afferents. Vibratory noise significantly reduced the precision of speed discrimination, and the effect was much stronger on the fine-textured than on the ridged surface. On both surfaces, masking vibrations at intermediate frequencies of 64 Hz (65-μm peak-to-peak amplitude) and 128 Hz (10 μm) had the strongest effect, followed by high-frequency vibrations of 256 Hz (1 μm) and low-frequency vibrations of 32 Hz (50 and 25 μm). These results are consistent with our hypothesis that slip-induced vibrations concur to the discrimination of tactile speed.

Softness Discrimination With a Tool

2000 ◽  
Vol 83 (4) ◽  
pp. 1777-1786 ◽  
Author(s):  
Robert H. LaMotte
Keyword(s):  
Grip Force ◽  
Precision Grip ◽  
Sensory Information ◽  
Mechanical Contact ◽  
Experimental Conditions ◽  
Tactile Cues ◽  
The Subject ◽  
Kinesthetic Information ◽  
Contrast Discrimination ◽  
Anticipatory Motor Control

The abilities of humans to discriminate the softness of rubber objects of differing compliance with a hand-held tool (a stylus) was measured under experimental conditions that differed as to how the tool was used and the kind of sensory information available. When the subject actively tapped or pressed the compliant objects, they discriminated softness as well by means of a stylus as they did by contacting the objects directly with the fingerpad. Discrimination with the stylus was unaffected by whether the stylus was controlled by one or two fingers. While tapping or pressing a stylus held in a precision grip, the grip force increased before, reached a maximum at the same time as, and decreased in parallel with the compressional force. This relationship was suggestive of anticipatory motor control based on an internal model of the motor system and the physical properties of the object. Discrimination was significantly better when tapping as opposed to pressing the objects with the stylus. This was hypothesized as due to the presence of tactile cues generated by the rapid increase in force rate as the stylus struck and indented the object during tapping. During tapping, the magnitude and rate of compressional force produced by the stylus against the object were greater, the harder the object. An additional cue, possibly kinesthetic, during pressing and tapping was the magnitude of indentation of the specimen by the stylus that was greater, the softer the object. Subjects could discriminate differences on softness by tactile cues alone in the absence of kinesthetic when compliant objects were tapped at approximately the same velocity by the experimenter against a stylus in contact with the subject's passive fingerpad. Discrimination deteriorated if the softer specimen of a pair was tapped with a slightly greater velocity than the harder and not possible if the specimens were pressed against the stylus without generating tactile cues of mechanical contact. In contrast, discrimination was possible during active pressing and unaffected by variations in velocity during active tapping. It is concluded that during active movements, kinesthetic information and knowledge of central efferent commands provide useful cues that are not present during passive touch. These cues allow the observer to discriminate differences in object compliance not confounded by differences in applied velocity.

scholarly journals Movement-Related Feedback and Temporal Accuracy in Clarinet Performance

2009 ◽  
Vol 26 (5) ◽  
pp. 439-449 ◽  
Author(s):  
Caroline Palmer ◽  
Erik Koopmans ◽  
Janeen D. Loehr ◽  
Christine Carter
Keyword(s):  
Motion Capture ◽  
Music Performance ◽  
Sensory Information ◽  
Initial Contact ◽  
Finger Movements ◽  
Piano Performance ◽  
Timing Error ◽  
Tactile Information ◽  
Timing Accuracy ◽  
Clarinet Performance

SENSORY INFORMATION AVAILABLE WHEN MUSICIANS' fingers arrive on instrument keys contributes to temporal accuracy in piano performance (Goebl & Palmer, 2008). The hypothesis that timing accuracy is related to sensory (tactile) information available at finger-key contact was extended to clarinetists' finger movements during key depressions and releases that, together with breathing, determine the timing of tone onsets. Skilled clarinetists performed melodies at different tempi in a synchronization task while their movements were recorded with motion capture. Finger accelerations indicated consistent kinematic landmarks when fingers made initial contact with or release from the key surface. Performances that contained more kinematic landmarks had reduced timing error. The magnitude of finger accelerations on key contact and release was positively correlated with increased temporal accuracy during the subsequent keystroke. These findings suggest that sensory information available at finger-key contact enhances the temporal accuracy of music performance.

scholarly journals Effect of blocking tactile information from the fingertips on adaptation and execution of grip forces to friction at the grasping surface

2016 ◽  
Vol 115 (3) ◽  
pp. 1122-1131 ◽  
Author(s):  
Seda Bilaloglu ◽  
Ying Lu ◽  
Daniel Geller ◽  
John Ross Rizzo ◽  
Viswanath Aluru ◽  
...  
Keyword(s):  
Grip Force ◽  
Adaptive Modulation ◽  
Precision Grip ◽  
Surface Friction ◽  
Rate Of Change ◽  
Load Force ◽  
Tactile Discrimination ◽  
Tactile Information ◽  
Slip Ratio ◽  
Additional Layer

Adaptation of fingertip forces to friction at the grasping surface is necessary to prevent use of inadequate or excessive grip forces. In the current study we investigated the effect of blocking tactile information from the fingertips noninvasively on the adaptation and efficiency of grip forces to surface friction during precision grasp. Ten neurologically intact subjects grasped and lifted an instrumented grip device with 18 different frictional surfaces under three conditions: with bare hands or with a thin layer of plastic (Tegaderm) or an additional layer of foam affixed to the fingertips. The coefficient of friction at the finger-object interface of each surface was obtained for each subject with bare hands and Tegaderm by measuring the slip ratio (grip force/load force) at the moment of slip. We found that the foam layer reduced sensibility for two-point discrimination and pressure sensitivity at the fingertips, but Tegaderm did not. However, Tegaderm reduced static, but not dynamic, tactile discrimination. Adaptation of fingertip grip forces to surface friction measured by the rate of change of peak grip force, and grip force efficiency measured by the grip-load force ratio at lift, showed a proportional relationship with bare hands but were impaired with Tegaderm and foam. Activation of muscles engaged in precision grip also varied with the frictional surface with bare hands but not with Tegaderm and foam. The results suggest that sensitivity for static tactile discrimination is necessary for feedforward and feedback control of grip forces and for adaptive modulation of muscle activity during precision grasp.

scholarly journals Spatio-temporal characteristics of frictional properties on the subducting Pacific Plate off the east of Tohoku district, Japan estimated from stress drops of small earthquakes

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Takuji Yamada ◽  
Meitong Duan ◽  
Jun Kawahara
Keyword(s):  
Stress Drop ◽  
Tohoku Earthquake ◽  
Pacific Plate ◽  
2011 Tohoku Earthquake ◽  
Plate Interface ◽  
The 2011 Tohoku Earthquake ◽  
Frictional Properties ◽  
Frictional Strength ◽  
Spatio Temporal ◽  
Stress Drops

AbstractThe east coast of the Tohoku district, Japan has a high seismicity, including aftershocks of the 2011 M9 Tohoku earthquake. We analyzed 1142 earthquakes with $$4.4 \le M_{W} \le 5.0$$ 4.4 ≤ M W ≤ 5.0 that occurred in 2003 through 2018 and obtained spatio-temporal pattern of stress drop on the Pacific Plate that subducts beneath the Okhotsk Plate. Here we show that small earthquakes at edges of a region with a large slip during the 2011 Tohoku earthquake had high values of stress drop, indicating that the areas had a high frictional strength and suppressed the coseismic slip of the 2011 Tohoku earthquake. In addition, stress drops of small earthquakes in some of the areas likely decreased after the 2011 Tohoku earthquake. This indicates that the frictional strength decreased at the areas due to the following aftershocks of the 2011 Tohoku earthquake, consistent with a high aftershock activity. This also supports that the frictional properties on a subducting plate interface can be monitored by stress drops of small earthquakes, as pointed out by some previous studies.

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