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.

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 Edge orientation perception during active touch

2018 ◽  
Vol 120 (5) ◽  
pp. 2423-2429 ◽  
Author(s):  
Derek Olczak ◽  
Vaishnavi Sukumar ◽  
J. Andrew Pruszynski
Keyword(s):  
Motor System ◽  
Active Touch ◽  
Contact Forces ◽  
Edge Orientation ◽  
Passive Touch ◽  
Per Se ◽  
Orientation Perception ◽  
Psychophysical Studies ◽  
Psychophysical Task ◽  
Better Than

Previous studies investigating the perceptual attributes of tactile edge orientation processing have applied their stimuli to an immobilized fingertip. Here we tested the perceptual attributes of edge orientation processing when participants actively touched the stimulus. Our participants moved their finger over two pairs of edges, one pair parallel and the other nonparallel to varying degrees, and were asked to identify which of the two pairs was nonparallel. In addition to the psychophysical estimates of edge orientation acuity, we measured the speed at which participants moved their finger and the forces they exerted when moving their finger over the stimulus. We report four main findings. First, edge orientation acuity during active touch averaged 12.4°, similar to that previously reported during passive touch. Second, on average, participants moved their finger over the stimuli at ~20 mm/s and exerted contact forces of ~0.3 N. Third, there was no clear relationship between how people moved their finger or how they pressed on the stimulus and their edge orientation acuity. Fourth, consistent with previous work testing tactile spatial acuity, we found a significant correlation between fingertip size and orientation acuity such that people with smaller fingertips tended to have better orientation acuity. NEW & NOTEWORTHY Edge orientation acuity expressed by the motor system during manipulation is many times better than edge orientation acuity assessed in psychophysical studies where stimuli are applied to a passive fingertip. Here we show that this advantage is not because of movement per se because edge orientation acuity assessed in a psychophysical task, where participants actively move their finger over the stimuli, yields results similar to previous passive psychophysical studies.

Adhesion measured on the attachment pads of Tettigonia viridissima (Orthoptera, insecta)

2000 ◽  
Vol 203 (12) ◽  
pp. 1887-1895 ◽  
Author(s):  
Y. Jiao ◽  
S. Gorb ◽  
M. Scherge
Keyword(s):  
Contact Area ◽  
Silicon Surface ◽  
Compressive Force ◽  
Adhesive Force ◽  
Applied Force ◽  
Adhesive Properties ◽  
Applied Forces ◽  
Series Of Experiments ◽  
Pore Canals ◽  
Adhesive Forces

The tarsi of the cricket Tettigonia viridissima bear flexible attachment pads that are able to deform, replicating the profile of a surface to which they are apposed. This attachment system is supplemented by a secretion produced by epidermal cells and transported onto the surface of the pad through the pore canals of the pad cuticle. This study shows that the secretion alone is necessary, but not sufficient, for adhesion. To account for the full adhesive force, the deformation of the pad and the resulting changes in contact area were considered. In two series of experiments, the adhesive properties of the secretion and the adhesion of the whole pad were measured using a force tester, the sensitivity of which ranged from micronewtons to centinewtons. The adhesive forces of the secretion measured between a smooth sapphire ball with a diameter of 1.47 mm and a flat silicon surface ranged from 0.1 to 0.6 mN. In a control experiment on the silicon surface without secretion, no adhesive force was measured. There was no dependence of the adhesive force on the applied compressive force. When an intact pad was pulled off a flat silicon surface, the adhesive force increased with increasing applied compressive force, but it did not increase further once the applied force exceeded a certain value. The saturated adhesive force, ranging from 0.7 to 1.2 mN, was obtained at applied forces of 0.7-1.5 mN. The hemispherical surface of the pad had a larger contact area and demonstrated greater adhesion under a larger applied force. Adhesion became saturated when a pad was deformed such that contact area was maximal. The tenacity (the adhesive force per unit area) was 1.7-2.2 mN mm(−)(2).

COGNITIVE STYLE PERFORMANCE AND FORM DISCRIMINATION

1973 ◽  
Vol 1 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Glen M. Vaught ◽  
Paul A. Roodin
Keyword(s):  
College Students ◽  
Cognitive Style ◽  
Field Dependence ◽  
Active Touch ◽  
Female College Students ◽  
Form Discrimination ◽  
Female College ◽  
Passive Touch ◽  
Field Independent ◽  
Field Dependent

Forty-two male and 42 female college students were subdivided into field independent, medium, and field dependent identity groups and matched for sex. Each subject was given 24 active and 24 passive touch form discrimination trials. The results showed that active touch form discrimination yielded fewer errors than passive touch and that females were better form discriminators than males. The interaction between field dependence, form discrimination and sex showed that in contrast to field independent subjects, field dependent males made more form discrimination errors while females improved. This interaction is discussed in relation to the field dependence literature.

Effect of Patellar Tendon Shortening on Tracking of the Patella

2005 ◽  
Vol 33 (10) ◽  
pp. 1565-1574 ◽  
Author(s):  
Neil Upadhyay ◽  
Samuel R. Vollans ◽  
Bahaa B. Seedhom ◽  
Roger W. Soames
Keyword(s):  
Patellar Tendon ◽  
Contact Area ◽  
Knee Flexion ◽  
Patellofemoral Joint ◽  
Contact Stresses ◽  
Contact Areas ◽  
Before And After ◽  
Joint Contact ◽  
Joint Biomechanics ◽  
Patellar Tendon Shortening

Background Although 10% postoperative patellar tendon shortening after bone–patellar tendon–bone autograft reconstruction of the anterior cruciate ligament has been reported, there are no published studies assessing the effect of shortening on patellofemoral joint biomechanics under physiological loading conditions. Purpose To investigate the influence of patellar tendon shortening on patellofemoral joint biomechanics. Study Design Controlled laboratory study. Methods The authors evaluated the patellofemoral contact area, the location of contact, and the patellofemoral joint reaction force and contact stresses in 7 cadaveric knees before and after 10% patellar tendon shortening. Shortening was achieved using a specially designed device. Experimental conditions simulating those occurring during level walking were employed: physiological quadriceps loads and corresponding angles of tibial rotation were applied at 15 °, 30 °, and 60 ° flexion of the knee. Patellofemoral joint contact areas were measured before and after shortening using the silicone oil–carbon black powder suspension squeeze technique. Results After patellar tendon shortening, patellofemoral joint contact areas were displaced proximally on the patellar surface and distally on the femoral surface. Although the contact area increased by 18% at 15 ° of knee flexion (P=. 04), no significant change occurred at 30 ° or 60 ° of knee flexion (P>. 05). Patellofemoral contact stress remained unchanged after patellar tendon shortening (P>. 05) at each flexion angle. Conclusion Our results suggest that a 10% shortening of the patellar tendon does not alter patellar contact stresses during locomotion. It is not clear whether apparent changes in contact location in all positions and contact area at 15 ° would have clinical consequences.

Load-Bearing at the Meniscofemoral Joint: An in vitro Study in the Canine Knee

2011 ◽  
Vol 1 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Pier Francesco Indelli ◽  
John A Szivek ◽  
Andrew Schnepp ◽  
William A Grana
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Knee Flexion ◽  
Femoral Condyle ◽  
Testing Machine ◽  
Partial Meniscectomy ◽  
Clinical Value ◽  
Contact Areas ◽  
Local Contact ◽  
Femoral Condyles

ABSTRACT Background The role of the menisci on tibial load transmission and stress distribution has been extensively studied, but few studies have focused on the meniscofemoral joint during physiologic weightbearing. The objective of this study was to determine the contact areas and local contact stresses at the meniscofemoral interface during physiologic range of motion and axial-loading in the canine knee and to determine the influence of a partial or total meniscectomy. Methods Both fresh-frozen knees of 3 hound-type canines were tested in a universal testing machine configured for an axial-load of 90-120 N. Measurement of the contact area and the local contact stress were done at three different knee angles (30; 50; 70) and with both menisci intact, after partial meniscectomy, and after total meniscectomy. Pressure distribution was estimated by using pressure sensitive film inserted above the menisci. Results After partial meniscectomy, contact areas at 50° of knee flexion decreased approximately 25% on both femoral condyles, and local contact stress increased 30% on the medial femoral condyle but remained unchanged on the lateral. After total meniscectomy, contact areas at 50° of knee flexion decreased approximately 75% on both femoral condyles, and local contact stress increased approximately 60% on the medial compartment and 100% on the lateral compartment. Conclusions These data suggest that a conservative partial meniscectomy leaves the meniscus with an inferior weight distribution function; decreasing, but not canceling the protection on the femoral hyaline cartilage. A dramatic decrease of contact area followed by an increase of local contact stress was noted after a total meniscectomy. The clinical value of this study is to emphasize the biomechanical value of surgical procedures addressing the repair of damaged menisci.

Relative Contributions of Active and Passive Touch to a Child's Knowledge of Physical Objects

1979 ◽  
Vol 48 (3_suppl) ◽  
pp. 1331-1346 ◽  
Author(s):  
Jeffrey L. Derevensky
Keyword(s):  
Information Processing ◽  
Shape Perception ◽  
Active Touch ◽  
Passive Touch ◽  
Haptic Exploration ◽  
Educational Implications ◽  
Physical Objects ◽  
Sensory Training

Literature was examined for contributions of both active and passive touch to a child's knowledge of shape perception. While research suggests that passive touch provides a useful function, haptic exploration or active touch is more effective for information processing. Various models and their educational implications for sensory training are discussed.

scholarly journals Alterations in the Plantar Pressure Patterns of Overweight and Obese Schoolchildren Due to Backpack Carriage

2013 ◽  
Vol 103 (4) ◽  
pp. 306-313 ◽  
Author(s):  
Massimiliano Pau ◽  
Bruno Leban ◽  
Marco Pau
Keyword(s):  
Contact Area ◽  
Plantar Pressure ◽  
Normal Weight ◽  
The Body ◽  
Long Term Effects ◽  
Contact Areas ◽  
Regular School ◽  
Plantar Pressures ◽  
School Day ◽  
Load Action

Background: Among other adverse consequences, childhood obesity is known to influence foot structure and functionality. Yet little information is available regarding how the physiologic foot-ground interaction is altered when a localized load is carried, as occurs in the case of schoolbags. We investigated plantar contact area and pressure modifications induced by backpack carriage under actual conditions. We hypothesized that a localized load acting on the body would further increase the already excessive plantar pressure that exists with overweight and obese status. Methods: Seventy overweight and obese schoolchildren aged 6 to 11 years underwent two 30-sec trials on a pressure platform during a regular school day, with and without a backpack. Total and subregion contact areas along with peak plantar pressures were obtained, and results were compared with those of an equal-numbered group of normal-weight schoolchildren. Results: Overweight and obese children generally had larger contact areas and higher peak plantar pressures compared with their normal-weight peers. In overweight and normal-weight participants, the backpack induced a similar generalized increase in contact area and pressures. However, the largest changes were observed in the forefoot, suggesting that load action tends to modify the physiologic pressure patterns. Conclusions: Backpack carriage raises the already elevated peak plantar pressures in overweight children during upright stance and modifies the physiologic pressure patterns. Further investigations are needed to clarify the features of such phenomenon when dynamic activities are performed and to verify the existence of fatigue and overexertion on the foot as well as other possible negative long-term effects. (J Am Podiatr Med Assoc 103(4): 306–313, 2013)

Dynamic instability of a spherical joint under various contact areas

2014 ◽  
Vol 229 (1) ◽  
pp. 54-58 ◽  
Author(s):  
Jaeyoung Kang
Keyword(s):  
Contact Area ◽  
Design Parameter ◽  
Friction Velocity ◽  
Dynamic Instability ◽  
Contact Geometry ◽  
Numerical Results ◽  
Spherical Joint ◽  
Contact Areas ◽  
Negative Friction ◽  
Conformal Contact

The contact area and the negative friction velocity slope on dynamic instability of spherical joint are theoretically investigated. The contact area may be influenced by the various loading and design conditions between a ball and socket. The non-conformal contact is adopted for the static and dynamic derivations. This contact geometry is selected as the major design parameter in this study. The numerical results reveal that the smaller contact area produces the higher propensity of modal instability.

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