Observation Of Hand Movements Research Articles

Mu-Suppression Neurofeedback Training Targeting the Mirror Neuron System: A Pilot Study

Neurofeedback training (NFT) is a promising adjuvant intervention method. The desynchronization of mu rhythm (8–13 Hz) in the electroencephalogram (EEG) over centro-parietal areas is known as a valid indicator of mirror neuron system (MNS) activation, which has been associated with social skills. Still, the effect of neurofeedback training on the MNS requires to be well investigated. The present study examined the possible impact of NFT with a mu suppression training protocol encompassing 15 NFT sessions (45 min each) on 16 healthy neurotypical participants. In separate pre- and post-training sessions, 64-channel EEG was recorded while participants (1) observed videos with various types of movements (including complex goal-directed hand movements and social interaction scenes) and (2) performed the "Reading the Mind in the Eyes Test" (RMET). EEG source reconstruction analysis revealed statistically significant mu suppression during hand movement observation across MNS-attributed fronto-parietal areas after NFT. The frequency analysis showed no significant mu suppression after NFT, despite the fact that numerical mu suppression appeared to be visible in a majority of participants during goal-directed hand movement observation. At the behavioral level, RMET accuracy scores did not suggest an effect of NFT on the ability to interpret subtle emotional expressions, although RMET response times were reduced after NFT. In conclusion, the present study exhibited preliminary and partial evidence that mu suppression NFT can induce mu suppression in MNS-attributed areas. More powerful experimental designs and longer training may be necessary to induce substantial and consistent mu suppression, particularly while observing social scenarios.

An inclusive paradigm to study mu-rhythm properties

Studying mu-rhythm in developmental disorders is crucial for identifying the origin of motor and social malfunctioning. However, the commonly used mu-rhythm experimental protocol, that requires following instructions, is challenging for children with motor and cognitive deficits. Here we present an inclusive experimental procedure that contains passive hand movement, closed and open eyes and hand movement observation and examine properties of EEG mu-rhythm obtained in this paradigm in 51 typically developing children and adults aged from 4 to 31 years. The independent component analysis (ICA) was used to separate occipital alpha- and mu-rhythm components and showed better performance than the channel-wise analysis. The identified mu-rhythm ICA components were localized above the left and right sensorimotor cortex, demonstrating suppression both to passive hand movement and hand movement observation and no difference in power between closed- and open-eye conditions. No interhemispheric differences were observed. The alpha-rhythm ICA components were localized in occipital regions and demonstrate characteristic suppression to open-eye conditions. The mu-rhythm frequency of peak suppression to passive hand movement as well as the amount of suppression increased with age. The beta-band mu-rhythm activity, while being less pronounced, was also suppressed both during passive hand movement and hand movement observation, while to a lesser degree than alpha-band mu during passive hand movement. Thus, we confirmed the classical properties of mu-rhythm and for the first time showed the developmental trajectory of mu-rhythm properties obtained during passive hand movement. The proposed experimental protocol and pipeline can be used further in studies of the mu-rhythm in challenging populations.

Partnering with people living with rheumatoid arthritis for care of their hands: Four case reports using relative motion orthoses

Study DesignCase report. IntroductionDespite better disease control with more effective medications, people with rheumatoid arthritis (RA) continue to experience persistent and fluctuating levels of pain, swelling and functional limitations in their hands. PurposeTo describe therapists and people living with RA working together to understand what could be occurring in their hands because of the RA and how relative motion (RM) orthoses may be used to self-manage common hand RA related problems. MethodsCase reports are used to demonstrate how patient self-report, clinical exam, and observation of hand movement and function are integrated into the design of RM orthoses for individuals with RA. The cases are supported by photos and videos, including a personal narrative video exploring 1 persons’ personal perspective on their use of RM orthoses. ResultsCase reports illustrate adaptive and/or protective RME orthoses use for RA related finger malalignment, tendon subluxation, joint pain and instability in the hand. The narrative video also introduces a person living with RA, who speaks candidly about her multiple RM orthoses and how she decides which orthosis is “best” for a given activity and the current level of RA related problems in her hands. DiscussionIt is not unusual for individuals with RA to have multiple RM orthoses, made for different purposes and fabricated from different materials. Mulitple RM orthosis options allows a person to select what is “best” for them, depending on the context of use and priorities or needs. ConclusionPartnering with people living with RA to understand how to use simple, low-profile, adaptive and protective RM orthoses may be an effective way to support self-management of common RA related hand problems.

Broken or socially mistuned mirroring in ASD? An investigation via transcranial magnetic stimulation.

Individuals with an autism spectrum disorder (ASD) experience persistent difficulties during social interactions and communication. Previously, it has been suggested that deficits in the so-called "mirror system," active during both action execution and observation, may underlie these social difficulties. It is still a topic of debate however whether deficiencies in the simulation of others' actions (i.e., "broken" mirroring) forms a general feature of ASD, or whether these mostly reflect a lack of social attunement. The latter would suggest an overall intact mirror system, but an impaired modulation of mirror activity according to variable social contexts. In this study, 25 adults with ASD and 28 age- and IQ-matched control participants underwent transcranial magnetic stimulation during the observation of hand movements under variable conditions. Hand movements were presented via a live interaction partner, either without social context to assess basic motor mirroring or in combination with direct and averted gaze from the actor to assess socially modulated mirroring. Overall, no significant group differences were revealed, indicating no generally diminished mirror activity in ASD. Interestingly however, regression analyses revealed that, among ASD participants, higher symptom severity was associated with both reduced basic motor mirroring and aberrant socially modulated mirroring (i.e., no enhancement of mirror system activity upon observation of the interaction partner's direct vs. averted gaze). These findings further challenge the notion that mirror system dysfunctions constitute a principal feature of ASD, but demonstrate that variations in mirroring may be related to differential expressions of ASD symptom severity. LAY SUMMARY: Our findings show similar activity levels in brain regions responsible for action simulation and understanding in adults with autism, compared to adults without autism. However, the presence of more severe autism symptoms was linked to reduced activity in these regions. This suggests lower levels of brain activity during action understanding in some, but not all, persons with autism, which may contribute to the social difficulties these persons experience in daily life.

Real time Bangla Digit Recognition through Hand Gestures on Air Using Deep Learning and OpenCV

Digit Recognition in real time through hand gestures has achieved great attention in machine learning and computer vision applications. This article focuses on identifying Bangla numerals in the air using hand motions. This research leads to the stairwell, allowing for more investigation in the same subject for various Bangla characters and even phrases. The major issue, however, is coping with the wide range of handwriting styles employed by various users. Many studies have been done on the identification of Bangla handwritten digits, but none has proven successful at recognizing Bangla digits in real time using hand gestures in the air. As a result, this article describes the creation of a Bangla digit recognition model that employs a Convolution Neural Network (CNN) to predict Bangla digits by observing hand movements in the air space. After a thorough examination, the suggested system attained a 98.37% accuracy on the BanglaLekha-Isolated dataset.

Temporal dynamics of the mirror neurons effect induced by observation of hand movement – a Transcranial Magnetic Stimulation study

Temporal dynamics of the mirror neurons effect induced by observation of hand movement – a Transcranial Magnetic Stimulation study

Effects of perinatal dioxin exposure on mirror neuron activity in 9-year-old children living in a hot spot of dioxin contamination in Vietnam

BackgroundFor 8 years, we have followed up a birth cohort comprising 241 mother-and-infant pairs living around the Da Nang airbase, a hot spot of dioxin contamination in Vietnam, and have reported the impacts of perinatal dioxin exposure on the neurodevelopment of children at various ages. In the present study, 9 years after birth, we investigated the effects of perinatal dioxin exposure on mu and theta rhythms by analyzing EEG power during the execution and observation of hand movements, which indicate mirror neuron system activity. MethodsOne hundred fifty-five 9-year-old children (86 boys and 69 girls) from the Da Nang birth cohort participated in the EEG examination with free viewing of hand movements. The dioxin levels in their mothers’ breast milk, measured 1 month after birth, were used as perinatal dioxin exposure markers. A log transform of the ratio of EEG power during execution or observation of the hand movements relative to the power during observation of a bouncing ball for theta and mu rhythms was used to evaluate mirror neuron activity. ResultsIn both brain hemispheres, the log power ratio in the theta band was significantly higher (i.e., less reduction of power) during observation of hand movements in girls exposed to high levels of TCDD. In boys, however, dioxin congeners other than TCDD, including HxCDDs and several PCDF congeners, contributed to increased log power ratios in the theta band. Particularly for PCDF congeners, the log power ratios in the lowest group among 4 exposure groups were lowest and significantly increased (i.e., decreasing reduction of power) with increasing dose. ConclusionPerinatal TCDD exposure may influence the mirror neuron system of the brain, which plays an important role for social-emotional behavior in children, particularly in girls living in a hot spot of dioxin contamination in Vietnam.

EEG mu suppression which differentiates self from others are correlated with empathic abilities

Previous studies have indicated that the sense of the “self” is associated with specific brain regions and neural network activity. Moreover, it has been reported that the mirror neuron system, which functions when executing or observing actions, might contribute to differentiating self from others and forming the basis of the sense of self. However, little is known to date about how the mirror neuron system, which reacts to both self and others’ actions, contributes to differentiating oneself from others. This study examined the characteristics of self-oriented activity in mirror neuron system signals using stimuli facilitating self-discrimination from others. The EEG resulting from observing hand movements of the self and another person were examined from the first-person and the third-person perspectives. The results indicated that mu suppression, which is an index of mirror neuron system activity, increased for the self from the first-person perspective, suggesting that mu suppression might reflect the difference between self and others. Conversely, the mu suppression's variations in self-other orientation increased in the third-person perspective, suggesting that individual differences in response orientation might be correlated with empathetic perspective-taking skills.

Influence of oxytocin administration on somatosensory evoked magnetic fields induced by median nerve stimulation during hand action observation in healthy male volunteers.

Watching another person’s hand movement modulates somatosensory evoked magnetic fields (SEFs). Assuming that the mirror neuron system may have a role in this phenomenon, oxytocin should enhance these effects. This single-blinded, placebo-controlled, crossover study therefore used magnetoencephalography (MEG) to investigate SEFs following electrical stimulation of the right median nerve in 20 healthy male participants during hand movement observation, which were initially presented as static images followed by moving images. The participants were randomly assigned to receive either oxytocin or saline during the first trial, with the treatment being reversed during a second trial. Log-transformed ratios of the N20 and N30 amplitudes were calculated and compared between moving and static images observations. Phase locking (calculated using intertrial phase coherence) of brain oscillations was also analyzed to evaluate alpha, beta and gamma rhythm changes after oxytocin administration. Log N30 ratios showed no significant changes after placebo administration but showed a decreasing tendency (albeit not significant) after placebo administration, which may suggest mirror neuron system involvement. In contrast, log N20 ratios were increased after placebo administration, but showed no significant change after oxytocin administration. Interestingly, the gamma band activity around N20 increased after placebo administration, suggesting that oxytocin exerted an analgesic effect on median nerve stimulation, and inhibited the gamma band increase. Oxytocin might therefore modulate not only the mirror neuron system, but also the sensory processing associated with median nerve stimulation.

АКТИВНОСТЬ ЗЕРКАЛЬНОЙ СИСТЕМЫ МОЗГА ПРИ ВОСПРИЯТИИ РЕЧИ И ЕЕ ВЗАИМОСВЯЗЬ С УРОВНЕМ ИНТЕЛЛЕКТА И ЭМПАТИИ

Previously, researchers hypothesized that the emergence of a system of mirror neurons (MNS) in the process of evolution could be a key mechanism that ensured the appearance of speech in humans. The aim of this work was to establish a relationship between the activity of the MNS in the perception of speech messages, indicators of intelligence and empathy. 25 healthy men and women (18–35 years old) were test subjects. We found that when observing hand movements with a computer mouse on a monitor screen and performing such movements independently, the power of EEG mu- and tau rhythms in the central and temporal cortical regions decreased in subjects. Based on this, we consider it probable that a certain contribution to the dynamics of neocortex activity in this situation is made by the activation of neurons in the MNS. Upon presentation of speech utterances to the research participants, the EEG amplitude changed, including in the range of the alpha rhythm. The most pronounced EEG changes developed 0.3–0.5 s after the end of the keywords. The processing of information during the perception of the phrase “I raise my hands and raise my head” in most of the subjects was reflected in the desynchronization of the indicated rhythm. The perception of the absurd phrase «I run around my hands and run around my head» was often accompanied by an increase in EEG oscillations in the range of the alpha rhythm. The perception of such a phrase, including the awareness of its contradiction to common sense, apparently caused stress in memory processes with an attempt to actively inhibit irrelevant information. These processes probably led to an increase in the amplitude of mu and tau rhythms in the central and temporal regions of the neocortex. The subjects with the highest IQs showed the greatest activation of the mu-rhythm when perceiving the correct phrase. When an absurd phrase was perceived, the greatest desynchronization in the central regions of the neocortex developed in subjects with high indices of various dimensions of empathy. Probably people with a high level of empathy, i.e. with a good development of emotional intelligence, they more easily and quickly realized the absurdity of the specified phrase. We consider the obtained results as evidence of the participation of MNS in the perception and awareness of speech messages describing a person’s physical actions.

Motor Cortical Activity during Observing a Video of Real Hand Movements versus Computer Graphic Hand Movements: An MEG Study.

Both action observation (AO) and virtual reality (VR) provide visual stimuli to trigger brain activations during the observation of actions. However, the mechanism of observing video movements performed by a person’s real hand versus that performed by a computer graphic hand remains uncertain. We aimed to investigate the differences in observing the video of real versus computer graphic hand movements on primary motor cortex (M1) activation by magnetoencephalography. Twenty healthy adults completed 3 experimental conditions: the resting state, the video of real hand movements (VRH), and the video of computer graphic hand movements (CGH) conditions with the intermittent electrical stimuli simultaneously applied to the median nerve by an electrical stimulator. The beta oscillatory activity (~20 Hz) in the M1 was collected, lower values indicating greater activations. To compare the beta oscillatory activities among the 3 conditions, the Friedman test with Bonferroni correction (p-value < 0.017 indicating statistical significance) were used. The beta oscillatory activities of the VRH and CGH conditions were significantly lower than that of the resting state condition. No significant difference in the beta oscillatory activity was found between the VRH and CGH conditions. Observing hand movements in a video performed by a real hand and those by a computer graphic hand evoked comparable M1 activations in healthy adults. This study provides some neuroimaging support for the use of AO and VR in rehabilitation, but no differential activations were found.

First-person perspective sharpens the understanding of distressful physical feelings associated with physical disability: A functional magnetic resonance study

We investigated whether observation of hand movements of people with hemiplegia by healthy individuals from the first-person perspective (FPP), compared to that from the third-person perspective (TPP), enables better understanding of disability-associated distress. We measured the neural activity of healthy individuals using functional magnetic resonance imaging while they observed hemiplegic movements from the FPP or TPP. Subjective assessment of the movements was determined with questionnaires. Compared to the TPP, the FPP elicited stronger activation in the inferior parietal lobule (IPL), right temporoparietal junction, and anterior cingulate cortex, which are associated with body representation, mentalization, and empathy, respectively. Enhanced IPL activity correlated positively with personal empathic traits. Observing movements of hemiplegic individuals from the FPP provided precise subjective understanding of the physically distressing aspects of their movements. These findings suggest that observing hemiplegic individuals from the FPP effectively improved observers’ understanding of disability-associated distress via body representation, mentalization, and empathy systems.

Observation of an expert model induces a skilled movement coordination pattern in a single session of intermittent practice

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 of 4 conditions: an observation group (OG), a slowed observation group (SOG), a random motion control group (RMCG) and a double physical training control group (DPTCG). The OG and SOG observed an expert model’s right hand performing the study task intermittently throughout acquisition, RMCG observed random dots movement instead of a model. Participants in the DPTCG received extra physical practice trials instead of the visually observed trials. Kinematic analysis revealed that only in conditions with observation of an expert model there was an instant robust improvement in motor planning of the task. This step-wise improvement was not only persistent in post-training retests but was also apparently implicit and subject to further incremental improvements in movement strategy over the period of 24 hours. The rapid change in motor strategy was accompanied by a transient within-session increase in spatial error for the observation groups, but this went away by 24 h post-training. We suggest that observation of hand movements of an expert model coaligned with self-produced movements during training can significantly condense the time-course of ecologically relevant drawing/writing skill mastery.

Effects of pseudoexperience on the understanding of hemiplegic movements in physical therapists: An fMRI study.

Physical therapists (PTs) are required to obtain an accurate understanding of the physical and mental states of their patients through observational assessment. To perform comprehensive observational assessments of patients' movements, PTs likely need to engage their own neural systems involved in action understanding and theory of mind, such as the action observation network (AON) and the right temporoparietal junction (rTPJ). Both systems are modulated by the observer's actual experience with the observed movements. Although, most PTs do not have physical experience with neurological disabilities, they routinely examine hemiplegic movements in stroke patients, and are thus considered to have acquired pseudoexperience with hemiplegia. We hypothesized that the PTs' pseudoexperience with hemiplegia would modulate the neural system associated with the understanding of others to elaborately comprehend the physical and mental states associated with hemiplegia. To investigate our hypothesis, we recruited 19 PTs and 19 naïve participants (NPs) to undergo functional MRI (fMRI) for cortical activity measurement while viewing videos of hemiplegic (HHM) and non-hemiplegic (non-HHM) hand movements. The participants subsequently viewed the same videos again outside the MRI scanner, and evaluated the observed hand movements via a questionnaire. Compared to the NPs, the PTs showed greater activation in the AON and rTPJ while observing HHMs. Psychophysiological interaction analyses revealed increased connectivity between the rTPJ and AON when the PTs viewed the HHMs. Behavioral analyses further indicated that the PTs more accurately assessed feeling states associated with HHMs than did NPs. These findings suggest that the PTs' pseudoexperience modulates the AON and rTPJ, enabling them to better understand hemiplegia-associated feeling states.

The introduction of IMITATE-R and its comparison with the IMITATE treatment method in the naming ability of two Persian speaking aphasic patients

ABSTRACTMirror neurons that have properties of audio/visual-acuity play a key role in imitation of movement performance. Since speech is a collection of coordinated movements in the producing organs, observing and imitation of speech movements can stimulate these neurons. In addition, observing hand movements trigger some actions related to the verbal cortex in the network of mirror neurons. According to the hypothesis of mirror neurons, new therapeutic approaches, including IMITATE, have been proposed for patients with aphasia. In the present study, using the IMITATE programme, a new therapeutic approach called IMITATE-R was planned based on observation of oral movements, hand gestures, and imitation of oral movements. Afterward, the IMITATE and IMITATE-R methods were compared with each other on naming skills of two Persian people with aphasia. The results showed that the rate of benefit from each treatment in each client was proportional to its individual and linguistic characteristics; however, in both patients, the IMITATE-R method was more effective in improving the naming skill. The results of this study were aimed at confirming the hypothesis of mirror neurons and the use of methods are based on action-observation for the treatment of patients with aphasia.

The role of head and hand movements for infants\u2019 predictions of others\u2019 actions

In everyday life, both the head and the hand movements of another person reveal the other’s action target. However, studies on the development of action prediction have primarily included displays in which only hand and no head movements were visible. Given that infants acquire in their first year both the ability to follow other’s gaze and the ability to predict other’s reaching actions, the question is whether they rely mostly on the hand or the head when predicting other’s manual actions. The current study aimed to provide an answer to this question using a screen-based eye tracking setup. Thirteen-month-old infants observed a model transporting plastic rings from one side of the screen to the other side and place them on a pole. In randomized trials the model’s head was either visible or occluded. The dependent variable was gaze-arrival time, which indicated whether participants predicted the model’s action targets. Gaze-arrival times were not found to be different when the head was visible or rendered invisible. Furthermore, target looks that occurred after looks at the hand were found to be predictive, whereas target looks that occurred after looks at the head were reactive. In sum, the study shows that 13-month-olds are capable of predicting an individual’s action target based on the observed hand movements but not the head movements. The data suggest that earlier findings on infants’ action prediction in screen-based tasks in which often only the hands were visible may well generalize to real-life settings in which infants have visual access to the actor’s head.

Transcranial alternating current stimulation to the inferior parietal lobe decreases mu suppression to egocentric, but not allocentric hand movements

Egocentric vs. allocentric perspective during observation of hand movements has been related to self-other differentiation such that movements observed from an egocentric viewpoint have been considered as self-related while movements observed from an allocentric viewpoint have been considered as belonging to someone else. Correlational studies have generally found that egocentric perspective induces greater neurophysiological responses and larger behavioral effects compared to an allocentric perspective. However, recent studies question previous findings by reporting greater (μ) suppression and greater transcranial magnetic stimulation (TMS)-induced motor-evoked potentials (MEPs) during observation of allocentric compared to egocentric movements. Furthermore, self-other differentiation has been generally related to activity within the inferior parietal lobe (IPL), but direct evidence for a causal and functional role of IPL in self-other differentiation is lacking. The current study was therefore designed to investigate the influence that IPL exerts on self-other differentiation. To this aim, we measured the impact of individually adjusted alpha-tuned transcranial alternating current stimulation (tACS) applied over IPL on μ-suppression during hands movement observation from an egocentric and allocentric perspective. Electroencephalography (EEG) was recorded during movement observation before and immediately after tACS. Results demonstrated that tACS decreased μ-reactivity over sensorimotor (but not visual) regions for egocentric (but not allocentric) movement observation providing direct evidence for a causal involvement of IPL in the observation of self- but not other-related hand movement.

Effects of observation of hand movements reflected in a mirror on cortical activation in patients with stroke.

[Purpose] The purpose of this study was to examine what changes occur in brain waves when patients with stroke receive mirror therapy intervention. [Subjects and Methods] The subjects of this study were 14 patients with stroke (6 females and 8 males). The subjects were assessed by measuring the alpha and beta waves of the EEG (QEEG-32 system CANS 3000). The mirror therapy intervention was delivered over the course of four weeks (a total of 20 sessions). [Results] Relative alpha power showed statistically significant differences in the F3, F4, O1, and O2 channels in the situation comparison and higher for hand observation than for mirror observation. Relative beta power showed statistically significant differences in the F3, F4, C3, and C4 channels. [Conclusion] This study analyzed activity of the brain in each area when patients with stroke observed movements reflected in a mirror, and future research on diverse tasks and stimuli to heighten activity of the brain should be carried out.

Direct eye contact enhances mirroring of others’ movements: A transcranial magnetic stimulation study

Direct eye contact is a powerful social cue to regulate interpersonal interactions. Previous behavioral studies showed a link between eye contact and motor mimicry, indicating that the automatic mimicry of observed hand movements is significantly enhanced when direct eye contact exists between the observer and the observed model. In the present study, we aim to investigate the neurophysiological basis of the previously reported behavioral enhancements. Here, transcranial magnetic stimulation (TMS) was applied to assess changes in cortico-motor excitability at the level of the primary motor cortex (M1) to explore whether and how the motor system is facilitated from observing others’ hand movements and, in particular, how this process is modulated by eye contact. To do so, motor evoked potentials (MEPs) were collected from two hand muscles while participants received single-pulse TMS and naturally observed video clips of an actor showing hand opening movements or static hands. During the observation, either direct or averted eye gaze was established between the subject and the observed actor. Our findings show a clear effect of eye gaze on observation-induced motor facilitation. This indicates that the mapping or ‘mirroring’ of others' movements is significantly enhanced when movement observation is accompanied by direct eye gaze compared to averted eye gaze. Our results support the notion that eye contact is a powerful social signal with the ability to direct human non-verbal social behavior. Furthermore, our findings are important for understanding the role of the mirror motor system in the mapping of socially relevant actions.

Grasping others' movements: Rapid discrimination of object size from observed hand movements.

During reach-to-grasp movements, the hand is gradually molded to conform to the size and shape of the object to be grasped. Yet the ability to glean information about object properties by observing grasping movements is poorly understood. In this study, we capitalized on the effect of object size to investigate the ability to discriminate the size of an invisible object from movement kinematics. The study consisted of 2 phases. In the first action execution phase, to assess grip scaling, we recorded and analyzed reach-to-grasp movements performed toward differently sized objects. In the second action observation phase, video clips of the corresponding movements were presented to participants in a two-alternative forced-choice task. To probe discrimination performance over time, videos were edited to provide selective vision of different periods from 2 viewpoints. Separate analyses were conducted to determine how the participants' ability to discriminate between stimulus alternatives (Type I sensitivity) and their metacognitive ability to discriminate between correct and incorrect responses (Type II sensitivity) varied over time and viewpoint. We found that as early as 80 ms after movement onset, participants were able to discriminate object size from the observation of grasping movements delivered from the lateral viewpoint. For both viewpoints, information pickup closely matched the evolution of the hand's kinematics, reaching an almost perfect performance well before the fingers made contact with the object (60% of movement duration). These findings suggest that observers are able to decode object size from kinematic sources specified early on in the movement. (PsycINFO Database Record