scholarly journals Active palpation underlying shape perception is shaped by physiological thresholds and experience

2020 ◽  
Author(s):  
Neomi Mizrachi ◽  
Guy Nelinger ◽  
Ehud Ahissar ◽  
Amos Arieli
Keyword(s):  
High Speed ◽  
Shape Perception ◽  
Tactile Perception ◽  
Hand Movements ◽  
Hand Tracking ◽  
Experimental Session ◽  
Temporal Adaptation ◽  
Planar Shape ◽  
Contour Following ◽  
Human Participants

ABSTRACTHand movements are essential for tactile perception of objects. However, why different individuals converge on specific movement patterns is not yet clear. Focusing on planar shape perception, we tracked the hands of 11 participants while they practiced shape recognition. Our results show that planar shape perception is mediated by contour-following movements, either tangential to the contour or spatially-oscillating perpendicular to it, and by scanning movements, crossing between distant parts of the shapes’ contour. Both strategies exhibited non-uniform coverage of the shapes’ contours. We found that choice of strategy during the first experimental session was strongly correlated with two idiosyncratic parameters: participants with lower tactile resolution tended to move faster; and faster-adapting participants tended to employ oscillatory movements more often. In addition, practicing on isolated geometric features increased the tendency to use the contour-following strategy. These results provide insights into the processes of strategy selection in tactile perception.SIGNIFICANCE STATMENTHand movements are integral components of tactile perception. Yet, the specific motion strategies used to perceive specific objects and features, and their dependence on physiological features and on experience, are understudied. Focusing on planar shape perception and using high-speed hand tracking we show that human participants employ two basic palpation strategies: Contour-following and scanning. We further show that the strategy chosen by each participant and its kinematics depend strongly on the participant’s physiological thresholds – indicative of spatial resolution and temporal adaptation - and on their perceptual experience.

scholarly journals Idiosyncratic Functions of Active Touch Strategies in Shape Perception.

2021 ◽  
Author(s):  
Neomi Mizrachi ◽  
Guy Nelinger ◽  
Ehud Ahissar ◽  
Amos Arieli
Keyword(s):  
High Resolution ◽  
Shape Recognition ◽  
Recognition Task ◽  
Shape Perception ◽  
Physiological Parameters ◽  
Active Touch ◽  
Hand Movements ◽  
Dominant Hand ◽  
Planar Shape ◽  
Contour Following

Abstract Hand movements are essential for tactile perception of objects. However, the specific functions served by active touch strategies, and their dependence on physiological parameters, is unclear and understudied. Focusing on planar shape perception, we tracked at high resolution the hands of eleven participants during shape recognition task. Two dominant hand movements strategies were identified: Contour-following movements, either tangential to the contour or oscillating perpendicular to it, and exploration by scanning movements, crossing between distant parts of the shapes’ contour. Both strategies exhibited non-uniform coverage of the shapes’ contours. Idiosyncratic movement patterns were specific to the sensed object and could be explained in part by spatial and temporal tactile thresholds of the participant. Using simulations, we show how some strategy choices may affect receptors activation. These results suggest that motion strategies of active touch adapt to both the sensed object and to the perceiver’s physiological parameters.

scholarly journals Eye movements do not play an important role in the adaptation of hand tracking to a visuomotor rotation

2019 ◽  
Vol 121 (5) ◽  
pp. 1967-1976 ◽  
Author(s):  
Niels Gouirand ◽  
James Mathew ◽  
Eli Brenner ◽  
Frederic R. Danion
Keyword(s):  
Eye Movements ◽  
Time Course ◽  
Motor Behavior ◽  
Hand Movement ◽  
Visuomotor Adaptation ◽  
Online Control ◽  
Hand Movements ◽  
Hand Tracking ◽  
Gaze Fixation ◽  
The Gaze

Adapting hand movements to changes in our body or the environment is essential for skilled motor behavior. Although eye movements are known to assist hand movement control, how eye movements might contribute to the adaptation of hand movements remains largely unexplored. To determine to what extent eye movements contribute to visuomotor adaptation of hand tracking, participants were asked to track a visual target that followed an unpredictable trajectory with a cursor using a joystick. During blocks of trials, participants were either allowed to look wherever they liked or required to fixate a cross at the center of the screen. Eye movements were tracked to ensure gaze fixation as well as to examine free gaze behavior. The cursor initially responded normally to the joystick, but after several trials, the direction in which it responded was rotated by 90°. Although fixating the eyes had a detrimental influence on hand tracking performance, participants exhibited a rather similar time course of adaptation to rotated visual feedback in the gaze-fixed and gaze-free conditions. More importantly, there was extensive transfer of adaptation between the gaze-fixed and gaze-free conditions. We conclude that although eye movements are relevant for the online control of hand tracking, they do not play an important role in the visuomotor adaptation of such tracking. These results suggest that participants do not adapt by changing the mapping between eye and hand movements, but rather by changing the mapping between hand movements and the cursor’s motion independently of eye movements. NEW & NOTEWORTHY Eye movements assist hand movements in everyday activities, but their contribution to visuomotor adaptation remains largely unknown. We compared adaptation of hand tracking under free gaze and fixed gaze. Although our results confirm that following the target with the eyes increases the accuracy of hand movements, they unexpectedly demonstrate that gaze fixation does not hinder adaptation. These results suggest that eye movements have distinct contributions for online control and visuomotor adaptation of hand movements.

Identify Finger Rotation Angles with ArUco Markers and Action Cameras

2022 ◽  
pp. 1-25
Author(s):  
Tianyun Yuan ◽  
Yu Song ◽  
Gerald A. Kraan ◽  
Richard HM Goossens
Keyword(s):  
Coordinate System ◽  
Degrees Of Freedom ◽  
Tracking System ◽  
Hand Movements ◽  
Hand Tracking ◽  
Human Hand ◽  
Joint Rotation ◽  
Hand Joints ◽  
Camera Coordinate System ◽  
Joint Experiment

Abstract Measuring the motions of human hand joints is often a challenge due to the high number of degrees of freedom. In this study, we proposed a hand tracking system utilizing action cameras and ArUco markers to continuously measure the rotation angles of hand joints. Three methods were developed to estimate the joint rotation angles. The pos-based method transforms marker positions to a reference coordinate system (RCS) and extracts a hand skeleton to identify the rotation angles. Similarly, the orient-x-based method calculates the rotation angles from the transformed x-orientations of the detected markers in the RCS. In contrast, the orient-mat-based method first identifies the rotation angles in each camera coordinate system using the detected orientations, and then, synthesizes the results regarding each joint. Experiment results indicated that the repeatability errors with one camera regarding different marker sizes were around 2.64 to 27.56 degrees and 0.60 to 2.36 degrees using the marker positions and orientations respectively. When multiple cameras were employed to measure the joint rotation angles, the angles measured by using the three methods were comparable with that measured by a goniometer. Despite larger deviations occurred when using the pos-based method. Further analysis indicated that the results of using the orient-mat-based method can describe more types of joint rotations, and the effectiveness of this method was verified by capturing hand movements of several participants. Thus it is recommended for measuring joint rotation angles in practical setups.

scholarly journals Auguste Rodin Draws Blind: An Art and Psychology Study

Leonardo ◽  
2019 ◽  
Vol 52 (5) ◽  
pp. 483-491
Author(s):  
John Tchalenko ◽  
R. Chris Miall
Keyword(s):  
Line Shape ◽  
High Speed ◽  
Direct Vision ◽  
Hand Movements ◽  
Drawing Process ◽  
Art Students ◽  
Auguste Rodin ◽  
Motor Strategy ◽  
Static Images ◽  
Complex Lines

Late in his life Rodin produced many thousand “instant drawings.” He asked models to make natural energetic movements, and he would draw them at high speed without looking at his hand or paper. To help understand his “blind drawing” process, the authors tracked the eye and hand movements of art students while they drew blind, copying complex lines presented to them as static images. The study found that line shape was correctly reproduced, but scaling could show major deficiencies not seen in Rodin's sketches. The authors propose that Rodin's direct vision-to-motor strategy, coupled with his high expertise, allowed him to accurately depict in one sweep the entire model, without “thoughts arresting the flow of sensations.”

scholarly journals Unexpected complexity of everyday manual behaviors

2019 ◽  
Author(s):  
Yuke Yan ◽  
James M. Goodman ◽  
Dalton D. Moore ◽  
Sara A. Solla ◽  
Sliman J. Bensmaia
Keyword(s):  
American Sign Language ◽  
Neural Control ◽  
Dimensional Space ◽  
Hand Movements ◽  
Higher Dimensional ◽  
Dimensionality Reduction Technique ◽  
Hand Control ◽  
Components Analysis ◽  
Human Participants ◽  
The Brain

AbstractHow does the brain control an effector as complex and versatile as the hand? One possibility is that the neural control of the hand is simplified by limiting the space of achievable hand postures. Indeed, hand kinematics can be largely accounted for within a small subspace of postures. This oft replicated finding has been interpreted as evidence that hand postures are confined to this subspace, and that leaving it volitionally is impossible. A prediction from this hypothesis is that measured hand movements that fall outside of this subspace reflect motor or measurement noise. To address this question, we track hand postures of human participants as they perform two distinct tasks – grasping and signing in American Sign Language. We then apply a standard dimensionality reduction technique – principal components analysis – and replicate the finding that hand movements can be largely described within a reduced subspace. However, we show that postural dimensions that fall outside of this subspace are highly structured and task dependent, suggesting that they too are under volitional control. We conclude that hand control occupies a higher dimensional space than previously considered, and propose that controlling the complexity of hand movements is well within the scope of the brain’s computational power.

scholarly journals Targeted memory reactivation during sleep elicits neural signals related to learning content

2018 ◽  
Author(s):  
Boyu Wang ◽  
James Antony ◽  
Sarah Lurie ◽  
Paula P Brooks ◽  
Ken A Paller ◽  
...  
Keyword(s):  
Slow Wave Sleep ◽  
Activity Patterns ◽  
Discrimination Performance ◽  
Strong Relationship ◽  
Sleep Eeg ◽  
Hand Movements ◽  
Neural Signals ◽  
Learning Content ◽  
Right Hand ◽  
Human Participants

Reactivation of learning-related neural activity patterns is thought to drive memory stabilization. However, finding reliable, non-invasive, content-specific indicators of reactivation remains a central challenge. Here, we attempted to decode the content of reactivated memories in the electroencephalogram (EEG) during sleep. During encoding, human participants learned to associate spatial locations of visual objects with left- or right-hand movements, and each object was accompanied by an inherently related sound. During subsequent slow-wave sleep within an afternoon nap, we presented half of the sound cues that were associated (during wake) with left- and right-hand movements before bringing participants back for a final post-nap test. We trained a classifier on sleep EEG data (focusing on lateralized EEG features that discriminated left- vs. right-sided trials during wake) to predict learning content when we reactivated the memories during sleep. Discrimination performance was significantly above chance and predicted subsequent memory, supporting the idea that reactivation leads to memory stabilization. Moreover, these lateralized signals increased with post-cue spindle power, demonstrating that reactivation has a strong relationship with spindles. These results show that lateralized activity related to individual memories can be decoded from sleep EEG, providing an effective indicator of offline reactivation.

Computer control in human-machine interaction systems by hand movements

2021 ◽  
pp. 42-48
Author(s):  
Hoa Tat Thang
Keyword(s):  
Physical Disabilities ◽  
Computer Control ◽  
Recognition System ◽  
Body Language ◽  
Hand Movements ◽  
Hand Tracking ◽  
Human Machine Interaction ◽  
Interactive Applications ◽  
People With Physical Disabilities ◽  
Machine Interaction

Computers have become popular in recent years. The forms of human-computer interaction are increasingly diverse. In many cases, controlling the computer is not only through the mouse and keyboard, but humans must control the computer through body language and representation. For some people with physical disabilities, controlling the computer through hand movements is essential to help them interact with the computer. The field of simulation also needs these interactive applications. This paper studies a solution to build a hand tracking and gesture recognition system that allows cursor movement and corresponding actions with mouse and keyboard. The research team confirms that the system works stably, accurately and can control the computer instead of a conventional mouse and keyboard through the implementation and evaluation.

scholarly journals Tele-Presence Microscopy: An Interactive Multi-User Environment For Collaborative Research using High Speed Networks and The Internet

1995 ◽  
Vol 53 ◽  
pp. 14-15 ◽  
Author(s):  
Nestor J. Zaluzec
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
Experimental Session ◽  
Host Institution ◽  
High Speed Networks ◽  
Interactive Mode ◽  
Scientific Investigations ◽  
On Line ◽  
Operation Control ◽  
Non Local

Tele-Presence Microscopy (TPM) is an advanced concept in the integration of computers and high speed networks with scientific instruments for operation, control, communication and research which makes use of ANL's Advanced Analytical Electron Microscope (AAEM) and Analytical Scanning Electron Microscope (ASEM) as development/testbed sites. The implementation of a Tele-Presence Microscopy Facility allows a user from a remote location to either observe and/or control state-of-the-art instrumentation in a real time interactive mode. Using TPM, a user will be able to actively participate in scientific investigations at unique resources such as user facilities without being physically present at those locations. Manufacturers would be able to configure demonstration equipment which are accessible via the TPM system and thus allow prospective customers to remotely evaluate instrumentation before purchase. After acquisition, implementation by the manufacturer of a TPM system would allow remote service/diagnostics by a systems engineer who resides at the manufacturing site. Finally in an educational environment, students can initiate tele-presence operation of instruments which may not be available at their host institution, allowing widest possible access to unique facilities, Alternatively, should students have access to local equipment, they will have the opportunity of consulting an advisor or non-local expert in the field in an on-line mode during their actual experimental session, thus freeing valuable time which would be otherwise wasted during unproductive experiments.

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