Jason Friedman

Jason Friedman
Tel Aviv University | TAU · Department of Physical Therapy and Sagol School of Neuroscience

PhD (Weizmann Institute)

About

72
Publications
6,912
Reads
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806
Citations
Introduction
I am a senior lecturer in the Department of Physical Therapy and Sagol School of Neuroscience, Tel Aviv University. My research is in the field of human motor control. Specifically, I am interested in questions related to motor learning and computational modeling movements in typical populations, in development, and in motor disorders. Current topics that I am interested in include why it is so hard for us to make slow, smooth movements; how can we speed up motor learning; and can we combine targeted EEG and IMU feedback to improve rehabilitation outcomes. I'm also interested in how we can observe decision making through arm movements, what are the features of unconsciously produced movements, and how detailed kinematic analyses can benefit understanding motor disorders.
Additional affiliations
June 2009 - August 2012
Macquarie University
June 2007 - June 2009
Pennsylvania State University
Education
April 2002 - May 2007
Weizmann Institute of Science
Field of study
  • Applied Mathematics and Computer Science
October 1999 - February 2002
Weizmann Institute of Science
Field of study
  • Applied Mathematics and Computer Science
March 1996 - November 1998
Monash University (Australia)
Field of study
  • Computer Science

Publications

Publications (72)
Article
Full-text available
Background Therapists specializing in handwriting difficulties in children often address motor problems including both proximal and distal movements in the upper extremity. Kinematic measures can be used to investigate various aspects of handwriting. This study examined differences in movement patterns in proximal and distal joints of the upper ext...
Article
Assessing the cognitive impact of user interfaces is a shared focus of human-computer interaction researchers and cognitive scientists. Methods of cognitive assessment based on data derived from the system itself, rather than external apparatus, have the potential to be applied in a range of scenarios. The current study applied methods of analyzing...
Article
Hand-held pendulums can seemingly oscillate on their own, without perceived conscious control. This illusion, named after Chevreul, is likely a result of ideomotor movements. While this phenomenon was originally assumed to have a supernatural basis, it has been accepted for over 150 years that the movements are self-generated. However, until now, r...
Article
Full-text available
Assessment of self-feeding kinematics is seldom performed in an ecological setting. In preparation for development of an instrumented spoon for measurement of self-feeding in children with cerebral palsy (CP), the current work aimed to evaluate upper extremity kinematics of self-feeding in young children with typical development (TD) and a small, a...
Article
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Background The results of transcranial direct current stimulation (tDCS) studies that seek to improve motor performance for people with neurological disorders, by targeting the primary motor cortex, have been inconsistent. One possible reason, among others, for this inconsistency, is that very little is known about the optimal protocols for enhanci...
Preprint
Full-text available
A typical part of learning to play the piano is the progression through a series of practice units that focus on individual dimensions of the skill, such as hand coordination, correct posture, or correct timing. Ideally, a focus on a particular practice method should be made in a way to maximize the learner's progress in learning to play the piano....
Article
Background Individuals with osteoarthritis fall at a greater rate than the general population, likely as a result of weakness, pain, movement limitations, and a decline in balance. Due to the high prevalence of osteoarthritis in the population, understanding the mechanisms leading to greater fall risk is an important issue to better understand. Re...
Article
Full-text available
The Simon effect represents a phenomenon in which the location of the stimuli affects the speed and accuracy of the response, despite being irrelevant for the task demands. This is believed to be due to an automatic activation of a response corresponding to the location of the stimuli, which conflicts with the controlled decision process based on r...
Article
Study Design This is an intrasubject cross-sectional study. Introduction Upper limb injuries often require wearing an orthosis. Today, orthoses are custom-made by the clinician or purchased as an off-shelf product. Although 3D printing is a popular solution, the design and adjustment of an orthosis model according to patient-specific anatomy requi...
Article
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Analogies have been shown to improve motor learning in various tasks and settings. In this study we tested whether applying analogies can shorten the motor learning process and induce insight and skill improvement in tasks that usually demand many hours of practice. Kinematic measures were used to quantify participant’s skill and learning dynamics....
Article
Full-text available
Clinically feasible assessment of self-feeding is important for adults and children with motor impairments such as stroke or cerebral palsy. However, no validated assessment tool for self-feeding kinematics exists. This work presents an initial validation of an instrumented spoon (DataSpoon) developed as an evaluation tool for self-feeding kinemati...
Preprint
Full-text available
Hand-held pendulums can seemingly oscillate on their own, without perceived conscious control. This illusion, named after Chevreul, is likely a result of ideomotor movements. While this phenomenon was originally assumed to have a supernatural basis, it has been accepted for over 150 years that the movements are self-generated. However, until now, r...
Article
Full-text available
Although the fine-grained features of topographic maps in the somatosensory cortex can be shaped by everyday experience, it is unknown whether behavior can support the expression of somatotopic maps where they do not typically occur. Unlike the fingers, represented in all primates, individuated toe maps have only been found in non-human primates. U...
Article
Complex wrist motions are needed to complete various daily activities. Analyzing the multidimensional motion of the wrist is crucial for understanding our functional movement. Several studies have shown that numerous activities of daily livings (ADLs) are performed using an oblique plane of wrist motion from radial-extension to ulnar-flexion, named...
Article
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To evaluate normal and impaired control of anticipatory grip force (GF) modulation, we compared GF production during horizontal arm movements in healthy and post-stroke subjects, and, based on a physiologically feasible dynamic model, determined referent control variables underlying the GF–arm motion coordination in each group. 63% of 13 healthy an...
Article
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We tested how observation of a skilled pattern of planar movements can assist in the learning of a new motor skill, which otherwise requires rigorous long-term practice to achieve fast and smooth performance. Sixty participants performed a sequence of planar hand movements on pre-test, acquisition, post-test and 24 h post-training blocks, under 1 o...
Article
Background and objectives: The Seeking Proxies for Internal States (SPIS) model of obsessive-compulsive disorder (OCD) posits that obsessive-compulsive (OC) individuals have attenuated access to their internal states. Hence, they seek and rely on proxies, or discernible substitutes for these internal states. In previous studies, participants with...
Article
OBJECTIVE. The dart-throwing motion (DTM) is a multiplane wrist motion that is needed for many daily occupations. Mobilization along the DTM plane may be essential for rehabilitation after wrist injury, but DTM angles are reported for the dominant hand alone, so their relevance to injury in the nondominant hand cannot be surmised. The aim of this s...
Article
OBJECTIVE. We compared performance level and muscle activity patterns during shape copying and tracing in two positions, while sitting at a desk and while standing in front of a wall, between typically developing (TD) preschool children and children with mild disabilities (MD). METHOD. Twenty-two TD children (8 boys, 14 girls; mean [M] age = 5.2 yr...
Article
Introduction/Background Myoelectric prostheses inherently lack tactile feedback. Therefore, users of these devices have to rely on their visual feedback. Since daily tasks are often performed in a dual-task paradigm, e.g. holding a coffee cup while reading a newspaper or folding clothes while watching the television, they pose a cognitive challenge...
Article
Full-text available
Introduction/Background Upper limb (UL) paresis after stroke often leads to poor functional outcome. Application of transcranial direct current stimulation (tDCS) can modulate intra- and inter-hemispheric dynamics and promote treatment-related adaptive neural plasticity. However, the optimal stimulation mode for a patient with a given lesion patter...
Article
Objective: To evaluate the effects of adding Vibrotactile feedback (VTF) in myoelectric prosthesis users during performance of a functional task when visual feedback is disturbed. Design: A repeated-measures design with a counter-balanced order of three conditions. Setting: Laboratory setting. Participants: Transradial amputees using a myoel...
Article
Objective: To evaluate the effects of adding vibrotactile feedback to myoelectric prosthesis users on the performance time and visual attention in a dual-task paradigm. Design: A repeated-measures design with a counterbalanced order of two conditions. Setting: Laboratory setting. Subjects: Transradial amputees using a myoelectric prosthesis...
Article
We investigated whether adding vibrotactile feedback to a myoelectric-controlled hand, when visual feedback is disturbed, can improve performance during a functional test. For this purpose, able-bodied subjects, activating a myoelectric-controlled hand attached to their right hand performed the modified Box & Blocks test, grasping and manipulating...
Article
Full-text available
Coordination is often observed as body parts moving together. However, when producing force with multiple fingers, the optimal coordination is not to produce similar forces with each finger, but rather for each finger to correct mistakes of other fingers. In this study, we aim to determine whether and how this skill develops in children aged 4–12 y...
Article
Prosthesis users allocate visual attention to their prosthetic hand while performing activities of daily living (ADLs), due to absence of sensory feedback. Dual-task assignments present competition for visual attention and may affect the performance of ADLs. Vibrotactile feedback (VTF) is a frequently-used method to provide prosthesis users with ta...
Article
Full-text available
In this work, we ask how the probability of achieving synchrony in joint action is affected by the choice of motion parameters of each individual. We use the mirror game paradigm to study how changes in leader’s motion parameters, specifically frequency and peak velocity, affect the probability of entering the state of co-confidence (CC) motion: a...
Article
Full-text available
Acquisition of motor skills often involves the concatenation of single movements into sequences. Along the course of learning, sequential performance becomes progressively faster and smoother, presumably by optimization of both motor planning and motor execution. Following its encoding during training, how-to memory undergoes consolidation, reflect...
Article
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This study examines the role of the magnocellular system in the early stages of face perception, in particular sex categorization. Utilizing the specific property of magnocellular suppression in red light, we investigated visually guided reaching to low and high spatial frequency hybrid faces against red and grey backgrounds. The arm movement curva...
Article
Full-text available
This study examines the role of the magnocellular system in the early stages of face perception, in particular sex categorization. Utilizing the specific property of magnocellular suppression in red light, we investigated visually guided reaching to low and high spatial frequency hybrid faces against red and grey backgrounds. The arm movement curva...
Article
Full-text available
We are frequently changing the position of our bodies and body parts within complex environments. How does the brain keep track of one's own body? Current models of body ownership state that visual body ownership cues such as viewed object form and orientation are combined with multisensory information to correctly identify one's own body, estimate...
Article
The observation that a given task, e.g. producing a signature, looks similar when created by different motor commands and different muscles groups is known as motor equivalence. Relatively little data exists regarding the characteristics of motor equivalence in children. In this study, we compared the level of performance when performing a tracing...
Article
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A characteristic of visuomotor tracking of non-regular oscillating stimuli are high-frequency jittery corrective motions, oscillating around the tracked stimuli. However, the properties of these corrective jitter responses are not well understood. For example, does the jitter response show an idiosyncratic signature? What is the relationship betwee...
Article
Mechanical properties of human digits may have significant implications for the hand function. We quantified several mechanical characteristics of individual digits in young and older adults. Digit tip friction was measured at several normal force values using a method of induced relative motion between the digit tip and the object surface. A modif...
Article
Theories of decision-making have traditionally been constrained by reaction time data. A limitation of reaction time data, particularly for studying the temporal dynamics of cognitive processing, is that they index only the endpoint of the decision making process. Recently, physical reaching trajectories have been used as proxies for underlying men...
Article
Full-text available
All data-gloves are non-perfect measurement de-vices, and hence, reconstructing accurate virtual hand movements from real hand movements is a challenging task. This work implements three methods for performing this reconstruction, including a novel technique, and an extension to the 'zero hardware' method of [1]. Moreover, it presents the first sys...
Conference Paper
Previous research has shown that specific occipitotemporal areas process visual information of specific body parts such as hands. We used an fMRI block-design to investigate if anterior intraparietal and ventral premotor areas that have been shown to selectively process hand-related synchronous multisensory information also exhibit selective respon...
Article
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Research exploring the role of spatial frequencies in rapid stimulus detection and categorization report flexible reliance on specific spatial frequency (SF) bands. Here, through a set of behavioral and magnetoencephalography (MEG) experiments, we investigated the role of low spatial frequency (LSF) (<8 cycles/face) and high spatial frequency (HSF)...
Article
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Many motor skills, such as typing, consist of articulating simple movements into novel sequences that are executed faster and smoother with practice. Dynamics of re-organization of these movement sequences with multi-session training and its dependence on the amount of self-regulation of pace during training is not yet fully understood. In this stu...
Article
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Controlling finger impedance is critical for suc-cessful grasping. Understanding how humans achieve this is of great interest for learning about human motor control, as well as for ap-plications in robotic grasping. There have been a number of studies on finger impedance in both the robotics and biological fields. They almost exclusively consider o...
Article
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Developmental prosopagnosia (DP) is characterized by a selective deficit in face recognition despite normal cognitive and neurological functioning. Previous research has established configural processing deficits in DP subjects. Low spatial frequency (LSF) information subserves configural face processing. Using hybrid stimuli, here we examined the...
Article
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Numerous studies have examined control of force magnitude, but relatively little research has considered force direction control. The subjects applied isometric forces to a handle and the authors compared within-trial variability when force is produced in different directions. The standard deviation of the force parallel to the prescribed direction...
Article
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Distinct visual pathways are selectively tuned for processing specific spatial frequencies. Recently, Awasthi, Friedman, and Williams (2011) reported fast categorisation of faces at periphery, arguing for primacy of low spatial frequency (LSF) information in face processing. However, previous studies have also documented rapid categorization of pla...
Article
Full-text available
It is well accepted in the subliminal priming literature that task-level properties modulate nonconscious processes. For example, in tasks with a limited number of targets, subliminal priming effects are limited to primes that are physically similar to the targets. In contrast, when a large number of targets are used, subliminal priming effects are...
Article
Synchronously stimulating an artificial hand and a participant's hand that is hidden from view induces an apparent proprioceptive shift towards the artificial hand (Rubber Hand Illusion; RHI), such that participants subjectively report their hand location to be between the real and artificial hand. This effect is reduced or eliminated with asynchro...
Article
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We used the framework of the equilibrium-point hypothesis (in its updated form based on the notion of referent configuration) to investigate the multi-digit synergies at two levels of a hypothetical hierarchy involved in prehensile actions. Synergies were analyzed at the thumb-virtual finger (VF) level (VF is an imaginary digit with the mechanical...
Article
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Self-agency (SA) is the individual's perception that an action is the consequence of his/her own intention. The neural networks underlying SA are not well understood. We carried out a novel, ecologically valid, virtual-reality experiment using blood oxygen level–dependent functional magnetic resonance imaging (fMRI) where SA could be modulated in r...
Article
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Accurate control of forces produced by the fingers is essential for performing object manipulation. This study examines the indices of finger interaction when accurate time profiles of force are produced in different directions, while using one of the fingers or all four fingers of the hand. We hypothesized that patterns of unintended force product...
Conference Paper
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The masked congruence priming effect (MCE) has proven valuable in the investigation of nonconscious cognitive processes. While previous studies have used reaction time (RT) as the dependent variable, and found no difference between repeated primes (which also appear as targets) and novel primes (which do not appear as targets), this study, which ha...
Article
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In a multifinger cyclic force production task, the finger force variance measured across trials can be decomposed into two components, one that affects the combined force output ("bad variance") and one that does not ("good variance"). Previous studies have found similar time patterns of "bad variance" and force rate leading to an approximately lin...
Article
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The trajectory of the index finger during grasping movements was compared to the trajectories predicted by three optimization-based models. The three models consisted of minimizing the integral of the weighted squared joint derivatives along the path (inertia-like cost), minimizing torque change, and minimizing angular jerk. Of the three models, it...
Article
Full-text available
We examined how the digit forces adjust when a load force acting on a hand-held object continuously varies. The subjects were required to hold the handle still while a linearly increasing and then decreasing force was applied to the handle. The handle was constrained, such that it could only move up and down, and rotate about a horizontal axis. In...