Perception and Reproduction of Force Direction in the Horizontal Plane

2003 ◽  
Vol 90 (5) ◽  
pp. 3040-3053 ◽  
Author(s):  
D. Toffin ◽  
J. McIntyre ◽  
J. Droulez ◽  
A. Kemeny ◽  
A. Berthoz
Keyword(s):  
Horizontal Plane ◽  
Human Subjects ◽  
Mechanical Impedance ◽  
Human Beings ◽  
Force Vector ◽  
Reproduction Task ◽  
Perception Task ◽  
Limb Stiffness ◽  
Force Direction ◽  
Perceived Force

In this study, we evaluated the capacity of human beings to perceive and reproduce forces applied to the hand. We tested for perceptive distortions and/or privileged directions in the performance of these two tasks. Subjects resisted a reference force applied by a joystick in a given direction, with instructions to keep the hand at a constant position. In a perception task, subjects subsequently resisted a second such force, the direction of which they could adjust with a potentiometer; the task was to reorient the second force to be in the same perceived direction as the reference. In a reproduction task, subjects were instructed to push against the now elastically constrained joystick with the same force that was required to resist the initially applied reference force. Twenty-four reference force directions in the horizontal plane were tested twice each. We observed systematic distortions in the reproduction of force direction that were not present in the perception task. We further observed that the distortions could be predicted by anisotropy of limb stiffness and could be affected by manipulating the mechanical impedance of the hand-joystick interaction. We conclude that human subjects specify and store forces to be applied by the hand not in terms of a perceived force vector, but rather in terms of the motor activity required to resist or produce the force—i.e., subjects possess a multi-dimensional “sense of effort.”

Under- and Over-Estimation

2011 ◽  
Vol 58 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Virginie Crollen ◽  
Julie Castronovo ◽  
Xavier Seron
Keyword(s):  
Empirical Data ◽  
Accurate Estimation ◽  
Numerical Estimation ◽  
Production Task ◽  
Estimation Task ◽  
Reproduction Task ◽  
Perception Task ◽  
Adult Participants ◽  
Mapping Hypothesis ◽  
Task Perception

Over the last 30 years, numerical estimation has been largely studied. Recently, Castronovo and Seron (2007) proposed the bi-directional mapping hypothesis in order to account for the finding that dependent on the type of estimation task (perception vs. production of numerosities), reverse patterns of performance are found (i.e., under- and over-estimation, respectively). Here, we further investigated this hypothesis by submitting adult participants to three types of numerical estimation task: (1) a perception task, in which participants had to estimate the numerosity of a non-symbolic collection; (2) a production task, in which participants had to approximately produce the numerosity of a symbolic numerical input; and (3) a reproduction task, in which participants had to reproduce the numerosity of a non-symbolic numerical input. Our results gave further support to the finding that different patterns of performance are found according to the type of estimation task: (1) under-estimation in the perception task; (2) over-estimation in the production task; and (3) accurate estimation in the reproduction task. Moreover, correlation analyses revealed that the more a participant under-estimated in the perception task, the more he/she over-estimated in the production task. We discussed these empirical data by showing how they can be accounted by the bi-directional mapping hypothesis ( Castronovo & Seron, 2007 ).

scholarly journals Perception of combined translation and rotation in the horizontal plane in humans

2016 ◽  
Vol 116 (3) ◽  
pp. 1275-1285 ◽  
Author(s):  
Benjamin T. Crane
Keyword(s):  
Motion Perception ◽  
Horizontal Plane ◽  
Peak Velocity ◽  
Human Subjects ◽  
Human Motion ◽  
Subjective Equality ◽  
The Right ◽  
Biased Perception

Thresholds and biases of human motion perception were determined for yaw rotation and sway (left-right) and surge (fore-aft) translation, independently and in combination. Stimuli were 1 Hz sinusoid in acceleration with a peak velocity of 14°/s or cm/s. Test stimuli were adjusted based on prior responses, whereas the distracting stimulus was constant. Seventeen human subjects between the ages of 20 and 83 completed the experiments and were divided into 2 groups: younger and older than 50. Both sway and surge translation thresholds significantly increased when combined with yaw rotation. Rotation thresholds were not significantly increased by the presence of translation. The presence of a yaw distractor significantly biased perception of sway translation, such that during 14°/s leftward rotation, the point of subjective equality (PSE) occurred with sway of 3.2 ± 0.7 (mean ± SE) cm/s to the right. Likewise, during 14°/s rightward motion, the PSE was with sway of 2.9 ± 0.7 cm/s to the left. A sway distractor did not bias rotation perception. When subjects were asked to report the direction of translation while varying the axis of yaw rotation, the PSE at which translation was equally likely to be perceived in either direction was 29 ± 11 cm anterior to the midline. These results demonstrated that rotation biased translation perception, such that it is minimized when rotating about an axis anterior to the head. Since the combination of translation and rotation during ambulation is consistent with an axis anterior to the head, this may reflect a mechanism by which movements outside the pattern that occurs during ambulation are perceived.

Regulation of 3D Human Arm Impedance Through Muscle Co-Contraction

2013 ◽  
Author(s):  
Harshil Patel ◽  
Gerald O’Neill ◽  
Panagiotis Artemiadis
Keyword(s):  
Dimensional Space ◽  
Human Subjects ◽  
Three Dimensional ◽  
Mechanical Impedance ◽  
Dominant Factor ◽  
Robot Arm ◽  
End Point ◽  
Human Arm ◽  
Arm Muscles ◽  
Experimental Trials

Humans have the inherent ability of performing highly dexterous and skillful tasks with their arms, involving maintenance of posture, movement, and interaction with the environment. The latter requires the human to control the dynamic characteristics of the upper limb musculoskeletal system. These characteristics are quantitatively represented by inertia, damping, and stiffness, which are measures of mechanical impedance. Many previous studies have shown that arm posture is a dominant factor in determining the end point impedance on a horizontal (transverse) plane. This paper presents the characterization of the end point impedance of the human arm in three-dimensional space. Moreover, it models the regulation of the arm impedance with respect to various levels of muscle co-contraction. The characterization is made by route of experimental trials where human subjects maintained arm posture while their arms were perturbed by a robot arm. Furthermore, the subjects were asked to control the level of their arm muscles’ co-contraction, using visual feedback of their muscles’ activation, in order to investigate the effect of this muscle co-contraction on the arm impedance. The results of this study show a very interesting, anisotropic increase of arm stiffness due to muscle co-contraction. These results could lead to very useful conclusions about the human’s arm biomechanics, as well as many implications for human motor control-specifically the control of arm impedance through muscle co-contraction.

Personhood and Disorders of Consciousness: Finding Room in Person-Centered Healthcare

2020 ◽  
Vol 8 (3) ◽  
pp. 391
Author(s):  
Bianca Andrade ◽  
Marco Antonio Azevedo
Keyword(s):  
Human Subjects ◽  
Well Being ◽  
Disorders Of Consciousness ◽  
Human Beings ◽  
Mentally Handicapped ◽  
Definition Of

Advocates of the Person-Centered Healthcare (PCH) approach say that PCH is a response to a failure of caring for patients as persons. Nevertheless, there are many human subjects falling to fulfill the requirements of a traditional philosophical definition of personhood. Hence, if we take, PCH seriously, a greater clarification of the key terminology of PCH is urgently needed. It seems necessary, for instance, that the concept of the person should be extended in order to include those individuals with insipient or immature levels of consciousness, as well as those who are severely and permanently mentally handicapped. In this article, we will depart from some well-known philosophical concepts of what it means to be a person and try to offer a broader and more inclusive meaning. We suggest that persons are human beings with a socially recognized biography, which implies to recognize as persons individuals with necessities, but also with narratives about their interests and claims, expressed sometimes by other people related to them. This is particularly the case of individuals that suffer from severe disorders of consciousness. For those, is not only care that matters; respect matters too. Caregivers should therefore not only sympathetically care for the well-being of these people; they should also be concerned to respect their interests and claims by interpreting them empathetically, in the light of their biographical story. Our conclusion is that, in order to be coherent, PCH must consider individuals with severe disorders of consciousness as persons and we think that our revised concept of personhood fits with this requirement.

Effect of Motion Perception on Intertemporal Choice Is Associated With the Altered Time Perception

2018 ◽  
Vol 122 (1) ◽  
pp. 117-134 ◽  
Author(s):  
Xianchun Li ◽  
Di Yuan ◽  
Ying Fan ◽  
Chao Yan ◽  
Liangcai Gao
Keyword(s):  
Motion Perception ◽  
Time Perception ◽  
Intertemporal Choice ◽  
Critical Role ◽  
Random Order ◽  
Forward Motion ◽  
Reproduction Task ◽  
Perception Task ◽  
Time Reproduction ◽  
Motion Condition

Intertemporal choice refers to the choice between receiving a small immediate reward or a large delayed one. Previous studies have indicated that time perception plays a critical role in the intertemporal choice, and it could be affected by the features of the target stimulus in the time reproduction task, such as speed of movement and state of motion. However, there is no evidence about whether backward or forward motion perception could alter the intertemporal choice. Thus, in our current study, 29 participants were asked to perform two tasks in a random order. One was the intertemporal choice task after viewing videos containing moving elements with forward/backward directions as well as stationary ones, and another was the time perception task. We found that the discounting rate in intertemporal choice was significantly larger in backward motion condition than in both forward motion and stationary conditions, indicating that backward motion perception made participants more myopic (specifically, more likely to choose the smaller immediate reward instead of the large delayed one) during their decision-makings. Meanwhile, participants overestimated the temporal duration in a time perception task in backward motion condition compared to the other two conditions. Furthermore, the Pearson’s correlation analysis showed that the changes of the intertemporal choice induced by backward motion perception could be associated with the altered time perception. As far as we know, we provide the first evidence on influence of motion perception on the intertemporal choice as well as its possible cognitive correlates, which extend previous studies on cognitive basis of the intertemporal choices.

scholarly journals Introduction: Enquiries Into Contemporary Ritual Landscapes

2017 ◽  
Vol 11 (1) ◽  
pp. 5-17
Author(s):  
Pirjo Kristiina Virtanen ◽  
Eleonora A. Lundell ◽  
Marja-Liisa Honkasalo
Keyword(s):  
Human Subjects ◽  
Analytical Tool ◽  
Power Relation ◽  
Human Sciences ◽  
Human Beings ◽  
The Social ◽  
The World ◽  
Ritual Landscape ◽  
Scholarly Attention

Abstract ‘Landscape’ and ‘ritual’ have been largely discussed in the social and human sciences, although their inter-relatedness has gained little scholarly attention. Drawing on earlier studies of ritual and landscape, as well as the authors′ own ethnographic works, ‘ritual landscape’ is suggested here as a useful analytical tool with which to understand how landscapes are produced, and how they, in their turn, produce certain types of being. ‘Ritual landscape’ recognises different modalities of agency, power-relation, knowledge, emotion, and movement. The article shows how the subjectivity of other-than-human beings such as ancestors, earth formations, land, animals, plants and, in general, materiality of ritual contexts, shape landscapes. We argue that ways of perceiving landscape includes a number of material and immaterial aspects indicated by ways of moving through landscapes and interacting with different human and non-human subjects that come to inhabit the world, creating relations and producing agentive ensembles and complexes.

Extrathoracic airway resistance in man

1961 ◽  
Vol 16 (2) ◽  
pp. 326-330 ◽  
Author(s):  
Robert E. Hyatt ◽  
Roger E. Wilcox
Keyword(s):  
Flow Resistance ◽  
Airway Resistance ◽  
Human Subjects ◽  
Upper Airway ◽  
Normal Subjects ◽  
Mouth Breathing ◽  
Human Beings ◽  
Lung Inflation ◽  
Upper Airway Resistance ◽  
Extrathoracic Airway

Simultaneous extrathoracic and intrathoracic flow resistance was measured in 19 unanesthetized subjects during mouth breathing. Lateral intratracheal pressure was recorded from a needle introduced 2 cm below the larynx. The intratracheal-oral pressure gradient was recorded during various respiratory maneuvers. The pressure drop from esophagus to trachea was also recorded. The extrathoracic pressure-flow relationships were alinear. Large inter- and intrasubject variability in upper airway resistance was encountered. Some factors contributing to this variability were defined. The upper airway accounted for approximately 45% of the total airway resistance in nine normal and 20% in 10 emphysematous human subjects. Upper airway resistance decreased with increasing lung inflation in four normal subjects. The magnitude and potential variability of the upper airway resistance must be considered in evaluating maneuvers designed to alter intrathoracic flow resistance, especially in normal human beings. It appears that during mouth breathing the major component of the upper airway resistance is located in the larynx. Submitted on September 14, 1960

THE EFFECTS OF OXYGEN ON THE CIRCULATORY SYSTEM IN CONDITIONS OF ANOXIA AND ASPHYXIA

1945 ◽  
Vol 23e (6) ◽  
pp. 175-194 ◽  
Author(s):  
George W. Stavraky
Keyword(s):  
Blood Pressure ◽  
Blood Vessels ◽  
Human Subjects ◽  
Oxygen Deficiency ◽  
Animal Experiments ◽  
Circulatory System ◽  
Moderate Degree ◽  
Human Beings ◽  
Experimental Conditions ◽  
Transient Elevation

An analysis is presented of the blood pressure changes during anoxia, asphyxia, and oxygen administration, in 34 animal experiments. Similarly, in 30 human beings during decompression equivalent to altitudes ranging from 16,500 ft. to 29,000 ft., the blood pressure findings are correlated with the action of the heart and the state of the peripheral blood vessels, and the effect of subsequent administration of oxygen upon them is investigated.Sudden deprivation of oxygen leads to a vasoconstrictor response, which, in humans, manifests itself in facial pallor and elevation of the blood pressure. The administration of oxygen in the later stages of this response may produce a further transient elevation of the blood pressure, which is followed by a fall of blood pressure and slowing of the pulse. The rise of blood pressure caused by oxygen after a period of acute anoxia or asphyxia is due to an augmentation of the action of the heart and to an intensification of the vascular tone, the two phenomena contributing to the rise of blood pressure in a varying degree under different experimental conditions. In intact, anaesthetized cats the effect persists after adrenalectomy. In spinal preparations, previously kept on "minimal" respiration, the effect is greatly reduced by the removal of the suprarenal glands. The rise of blood pressure resulting from the administration of oxygen is abolished by the destruction of the spinal cord by pithing, and is therefore attributed to an excitation of the sympathetic centres. Evidence also is presented that suggests that the chemoreceptors participate in this response in intact anaesthetized animals.A protracted oxygen deficiency of a moderate degree leads to a vasodilator reaction. In human subjects it manifests itself in a gradual engorgement of the cutaneous blood vessels, often in a lowering of the blood pressure, and an increase of the pulse rate. Sudden administration of excessive quantities of oxygen under these conditions causes a further decline of blood pressure and a slowing of the pulse. An analysis of the fall of blood pressure caused by the administration of oxygen in conditions of prolonged hypo-oxygenation shows that it is not strictly related to changes in respiration or to acapnia, which occurs during breathing of air deficient in oxygen. Neither is it prevented by addition of carbon dioxide to the oxygen. However, under prevailing experimental conditions, this fall of blood pressure is almost invariably abolished by a bilateral vagotomy, is occasionally reduced by atropine, and is absent in spinal preparations, these observations indicating "that it is dependent on the functioning of the medullary reflex mechanisms.

scholarly journals Quantitative Characterization of Steady-State Ankle Impedance With Muscle Activation

2010 ◽  
Author(s):  
Hyunglae Lee ◽  
Patrick Ho ◽  
Mohammad A. Rastgaar ◽  
Hermano Igo Krebs ◽  
Neville Hogan
Keyword(s):  
Steady State ◽  
Vector Field ◽  
Degrees Of Freedom ◽  
Muscle Activation ◽  
Human Subjects ◽  
Mechanical Impedance ◽  
Field Analysis ◽  
Lower Extremity Function ◽  
Ankle Impedance

Characterization of multi-variable ankle mechanical impedance is crucial to understanding how the ankle supports lower-extremity function during interaction with the environment. This paper reports quantification of steady-state ankle impedance when muscles were active. Vector field approximation of repetitive measurements of the torque-angle relation in two degrees of freedom (inversion/eversion and dorsiflexion/plantarflexion) enabled assessment of spring-like and non-spring-like components. Experimental results of eight human subjects showed direction-dependent ankle impedance with greater magnitude than when muscles were relaxed. In addition, vector field analysis demonstrated a non-spring-like behavior when muscles were active, although this phenomenon was subtle in the unimpaired young subjects we studied.

GRAVITATION TOWARD WALLS AMONG HUMAN SUBJECTS

1976 ◽  
Vol 4 (1) ◽  
pp. 121-125
Author(s):  
James M. Dabbs ◽  
Patricia A. Wheeler
Keyword(s):  
Individual Differences ◽  
Human Subjects ◽  
The Other ◽  
Human Beings ◽  
Innate Behavior ◽  
Marked Individual ◽  
Social Encounters

In two studies, subjects in a classroom corridor who walked near the wall (“gravitators”) were contrasted with those who walked near the center (“nongravitators”). Gravitators were lower than non-gravitators on Autonomy and Defendence and appeared to be less responsive to other persons. Gravitation is an innate behavior among some animals; among human beings there are marked individual differences. Some social encounters may involve gravitation toward the other person as an object.

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