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This cross-sectional study investigated the associations among internal body orientation, body appreciation, intuitive eating, age, and BMI in men and women between 30 and 70 years old as delineated in the acceptance model of intuitive eating. Self-report measures were administered to a final sample of 522 individuals consisting of early-adult men (ages 30–44; n = 153), middle-adult men (ages 45–70; n = 108), early-adult women (ages 30–44; n = 135), and middle-adult women (ages 45–70; n = 126). Overall mean age was 45.03 (SD = 10.95). Structural equation modeling evidenced that, for both age groups of men and women, internal body orientation was positively associated with body appreciation and body appreciation was positively associated with intuitive eating. Internal body orientation was positively associated with intuitive eating in each group, except early-adult women. The associations among age and BMI with the aforementioned variables were inconsistent. Although evidencing measurement non-invariance among a number of parameters, multigroup structural invariance analyses showed that the associations among internal body orientation, body appreciation, intuitive eating, age, and BMI were invariant across each gender and age. These results further confirm components of the acceptance model of intuitive eating among men and women in early-adulthood and middle-adulthood.

Contains fulltext : 233650.pdf (Publisher’s version ) (Open Access) Background: In Coordinated Joint Engagement (CJE), children acknowledge that they and their social partners are paying attention to the same object. The achievement of CJE, critical for healthy development, is at risk in infants with visual impairment (VI). Research on CJE in these children is limited because investigators use a child's gaze switch between social partner and object to index CJE. Research is needed that identifies CJE in children with VI using behaviors that do not require normal vision and that explores the relationship between CJE and visual function. This study aimed to (a) develop a protocol for identifying CJE in children with VI, and (b) explore the relationship between CJE and infants' visual acuity (VA) and contrast sensitivity (CS), measured with Preferential Looking (PL) techniques and Visual Evoked Potential (VEP). Methods: A protocol that included 9 indices of CJE that did not require normal vision was developed to code videos of 20 infants with VI (mean age =1 year, 6 months, 27 days) and their caregivers. The percentage of CJE episodes in which each index was observed was calculated. Inter-coder reliability was measured using Cohen's Kappa. Linear regression analysis was used to examine the relationship between the infants' visual function and CJE. Results: Inter-rater reliability between a first coder and each of two second coders were 0.98 and 0.90 for determining whether the child participated in CJE. The following indices were observed the most (in 43-62 % of CJE): child's body orientation to caregiver, gaze switch between caregiver and object, and vocalization to caregiver. The only significant model included VA (measured with PL) as a single predictor and explained 26.8 % of the variance in CJE. Conclusions: The novel protocol can be used to identify CJE in children with VI with good inter-coder reliability. The data suggest that children with lower VA exhibited less CJE. 11 p.

ObjectiveTo test the hypothesis that lateropulsion is an entity expressing an impaired body orientation with respect to gravity in relation to a biased graviception and spatial neglect.MethodsData from the DOBRAS cohort (ClinicalTrials.gov: NCT03203109) were collected 30 days after a first hemisphere stroke. Lateral body tilt, pushing, and resistance were assessed with the Scale for Contraversive Pushing.ResultsAmong 220 individuals, 72% were upright and 28% showed lateropulsion (tilters [14%] less severe than pushers [14%]). The 3 signs had very high factor loadings (>0.90) on a same dimension, demonstrating that lateropulsion was effectively an entity comprising body tilt (cardinal sign), pushing, and resistance. The factorial analyses also showed that lateropulsion was inseparable from the visual vertical (VV), a criterion referring to vertical orientation (graviception). Contralesional VV biases were frequent (44%), with a magnitude related to lateropulsion severity: upright −0.6° (−2.9; 2.4), tilters −2.9° (−7; 0.8), and pushers −12.3° (−15.4; −8.5). Ipsilesional VV biases were less frequent and milder (p < 0.001). They did not deal with graviception, 84% being found in upright individuals. Multivariate, factorial, contingency, and prediction analyses congruently showed strong similarities between lateropulsion and spatial neglect, the latter encompassing the former.ConclusionsLateropulsion (pusher syndrome) is a trinity constituted by body tilt, pushing, and resistance. It is a way to adjust the body orientation in the roll plane to a wrong reference of verticality. Referring to straight above, lateropulsion might correspond to a form of spatial neglect (referring to straight ahead), which would advocate for 3D maps in the human brain involving the internal model of verticality.

Spontaneous postural sway during quiet standing has been considered a simple output error of postural control. However, as postural sway and inherent body orientation evoke compensatory activity of the plantar flexors, they might contribute to blood circulation under gravitational stress via the muscle pump. Hence, the present study employed an external support device to attenuate the plantar flexor activity in supported standing (SS), to experimentally identify its physiological impact on blood circulation. Eight healthy young subjects performed two 5-min quiet standing trials (i.e., normal standing (NS) and SS), and the beat-to-beat interval (RRI) and blood pressure (BP) were compared between trials. We confirmed that postural sway and corresponding plantar flexor activity, quantified by the anteroposterior displacement of the foot center of pressure and lower back position with respect to the wall, and by the amplitude of electromyography and mechanomyography, respectively, were attenuated in SS, while mean body orientation angle and relative position of the BP sensor were comparable to NS. The 5-min averages of diastolic BP and mean arterial pressure during SS were significantly higher than during NS, while RRI and systolic BP did not change. These could be interpreted as an increase in peripheral vascular resistance; meanwhile, in NS, this effect was replaced by the muscle pump of the plantar flexors. The muscle contractions related to spontaneous postural sway and body orientation produce substantial physiological impact on blood circulation during quiet standing.

Body orientation of gesture entails social‐communicative intention, and may thus influence how gestures are perceived and comprehended together with auditory speech during face‐to‐face communication. To date, despite the emergence of neuroscientific literature on the role of body orientation on hand action perception, limited studies have directly investigated the role of body orientation in the interaction between gesture and language. To address this research question, we carried out an electroencephalography (EEG) experiment presenting to participants (n = 21) videos of frontal and lateral communicative hand gestures of 5 s (e.g., raising a hand), followed by visually presented sentences that are either congruent or incongruent with the gesture (e.g., “the mountain is high/low…”). Participants underwent a semantic probe task, judging whether a target word is related or unrelated to the gesture‐sentence event. EEG results suggest that, during the perception phase of handgestures, while both frontal and lateral gestures elicited a power decrease in both the alpha (8–12 Hz) and the beta (16–24 Hz) bands, lateral versus frontal gestures elicited reduced power decrease in the beta band, source‐located to the medial prefrontal cortex. For sentence comprehension, at the critical word whose meaning is congruent/incongruent with the gesture prime, frontal gestures elicited an N400 effect for gesture‐sentence incongruency. More importantly, this incongruency effect was significantly reduced for lateral gestures. These findings suggest that body orientation plays an important role in gesture perception, and that its inferred social‐communicative intention may influence gesture‐language interaction at semantic level., We collected EEG when participants process visual sentences primed by frontal and lateral gestures. Lateral gestures elicited reduced beta band power decrease during perception. Additionally, in the visual sentences, the N400 effect, as derived from semantic incongruency between the critical word and the gesture prime, was reduced for lateral gestures.

The feeling of being addressed is the first step in a complex processing stream enabling successful social communication. Social impairments are a relevant characteristic of patients with major depressive disorder (MDD). Here, we investigated a mechanism which—if impaired—might contribute to withdrawal or isolation in MDD, namely, the neural processing of social cues such as body orientation and gesture. During funtional magnetic resonance imaging (fMRI) data acquisition, 33 patients with MDD and 43 healthy control subjects watched video clips of a speaking actor: one version with a gesture accompanying the speech and one without gesture. Videos were filmed simultaneously from two different viewpoints: one with the actor facing the viewer head‐on (frontal) and one side‐view (lateral). After every clip, the participants were instructed to evaluate whether they felt addressed or not. Despite overall comparable addressment ratings and a large overlap in activation patterns in MDD and healthy subjects for gesture processing, the anterior cingulate cortex, bilateral superior/middle frontal cortex, and right angular gyrus were more strongly activated in patients than in healthy subjects for the frontal conditions. Our analyses revealed that patients showed specifically higher activation than healthy subjects for the frontal condition without gesture in regions including the posterior cingulate cortex, left prefrontal cortex, and the left hippocampus. We conclude that MDD patients can recognize and interpret social cues such as gesture or body orientation; however, they seem to require more neural resources. This additional effort might affect successful communication and contribute to social isolation in MDD.

Once player tracking has been established as one of the main data sources in soccer, many challenges have emerged for data scientists, who attempt to recognize patterns from 2D trajectories in order to build tools that might help coaches to improve the performance of their teams. For instance, pass models predict where the ball should go next during pass events. However, existing models are mainly fed with players' location and prior data, hence omitting critical pieces of information such as players' body orientation. This paper presents a computational model to obtain pass feasibility maps, where player orientation is exploited and analysed. As a matter of fact, orientation proves to be crucial when modelling field-of-view and correct positioning of players, since it limits the potential receiving area of all candidates. Different proposals are given to evaluate the proposed pass feasibility map, reaching 0.46 and 0.79 in Top1 and Top3 accuracy, respectively, with a + 0.2 boost obtained after merging positional data with orientation.

We aimed to identify differences in kicking leg and torso mechanics between groups of rugby place kickers who achieve different performance outcomes, and to understand why these features are associated with varying levels of success. Thirty-three experienced place kickers performed maximum effort place kicks, whilst three-dimensional kinematic (240 Hz) and ground reaction force (960 Hz) data were recorded. Kicking leg and torso mechanics were compared between the more successful (‘long’) kickers and two sub groups of less successful kickers (’short’ and ‘wide-left’) using magnitude-based inferences and statistical parametric mapping. Short kickers achieved substantially slower ball velocities compared with the long kickers (20.8 ± 2.2 m/s vs. 27.6 ± 1.7 m/s, respectively) due to performing substantially less positive hip flexor (normalised mean values = 0.071 vs. 0.092) and knee extensor (0.004 vs. 0.009) joint work throughout the downswing, which may be associated with their more front-on body orientation, and potentially a lack of strength or intent. Wide-left kickers achieved comparable ball velocities (26.9 ± 1.6 m/s) to the long kickers, but they were less accurate due to substantially more longitudinal ball spin and a misdirected linear ball velocity. Wide-left kickers created a tension arc across the torso and therefore greater positive hip flexor joint work (normalised mean = 0.112) throughout the downswing than the long kickers. Whilst this may have assisted kicking foot velocity, it also induced greater longitudinal torso rotation during the downswing, and may have affected the ability of the hip to control the direction of the foot trajectory.

We examined the control of postural stability in preparation to a discrete, quick whole-body sway toward a target and back to the initial position. Several predictions were tested based on the theory of control with referent body orientation and the notion of multi-muscle synergies stabilizing center of pressure (COP) coordinate. Healthy, young adults performed fast, discrete whole-body motion forward-and-back and backward-and-back under visual feedback on the COP. We used two methods to assess COP stability, analysis of inter-trial variance and analysis of motor equivalence in the muscle activation space. Actions were always preceded by COP counter-movements. Backward COP shifts were faster, and the indices of multi-muscle synergies stabilizing COP were higher prior to those actions. Patterns of muscle activation at the motion onset supported the idea of a gradual shift in the referent body orientation. Prior to the backward movements, there was a trend toward higher muscle co-activation, compared to reciprocal activation. We found strong correlations between the sets of indices of motor equivalence and those of inter-trial variance. Overall, the results support the theory of control with referent coordinates and the idea of multi-muscle synergies stabilizing posture by confirming a number of non-trivial predictions based on these concepts. The findings favor using indices of motor equivalence in clinical studies to minimize the number of trials performed by each subject.

We used the 7.5% carbon dioxide (CO2) model of anxiety induction to investigate the effects of state anxiety on normal gait and gait when navigating an obstacle. Healthy volunteers (n = 22) completed a walking task during inhalations of 7.5% CO2 and medical air (placebo) in a within-subjects design. The order of inhalation was counterbalanced across participants and the gas was administered double-blind. Over a series of trials, participants walked the length of the laboratory, with each trial requiring participants to navigate through an aperture (width adjusted to participant size), with gait parameters measured via a motion capture system. The main findings were that walking speed was slower, but the adjustment in body orientation was greater, during 7.5% CO2 inhalation compared to air. These findings indicate changes in locomotor behaviour during heightened state anxiety that may reflect greater caution when moving in an agitated state. Advances in sensing technology offer the opportunity to monitor locomotor behaviour, and these findings suggest that in doing so, we may be able to infer emotional states from movement in naturalistic settings. Electronic supplementary material The online version of this article (10.1007/s00426-020-01393-2) contains supplementary material, which is available to authorized users.

Image based human behavior and activity understanding has been a hot topic in the field of computer vision and multimedia. As an important part, skeleton estimation, which is also called pose estimation, has attracted lots of interests. For pose estimation, most of the deep learning approaches mainly focus on the joint feature. However, the joint feature is not sufficient, especially when the image includes multi-person and the pose is occluded or not fully visible. This paper proposes a novel multi-task framework for the multi-person pose estimation. The proposed framework is developed based on Mask Region-based Convolutional Neural Networks (R-CNN) and extended to integrate the joint feature, body boundary, body orientation and occlusion condition together. In order to further improve the performance of the multi-person pose estimation, this paper proposes to organize the different information in serial multi-task models instead of the widely used parallel multi-task network. The proposed models are trained on the public dataset Common Objects in Context (COCO), which is further augmented by ground truths of body orientation and mutual-occlusion mask. Experiments demonstrate the performance of the proposed method for multi-person pose estimation and body orientation estimation. The proposed method can detect 84.6% of the Percentage of Correct Keypoints (PCK) and has an 83.7% Correct Detection Rate (CDR). Comparisons further illustrate the proposed model can reduce the over-detection compared with other methods.

Social cues such as gaze, head, and body orientation are essential for the survival of any social animal. The gaze cuing paradigm is a well-studied experimental manipulation, employed to detect automatic attentional shifts in humans. To the best of our knowledge, no previous study has tested non-primates in a paradigm that is similar to the one typically used on humans. Herein, three archerfish observed a conspecific picture oriented toward the right or the left, followed unpredictably by a visual target presented in the socially cued or un-cued location. Similar to the pattern observed in humans, fish demonstrated faster reaction times for targets presented at the socially cued location. Results suggest that social cues may have an early evolutionary origin and can elicit automatic attentional orienting even in species without a visual cortex.

In environments where orientation is ambiguous, the visual system uses prior knowledge about lighting coming from above to recognize objects, determine which way is up, and reorient the body. Here we investigated the extent with which assumed light from above preferences are affected by body orientation and the orientation of the retina relative to gravity. We tested the ability to extract shape-from-shading with seven human male observers positioned in multiple orientations relative to gravity using a modified KUKA anthropomorphic robot arm. Observers made convex-concave judgments of a central monocularly viewed stimulus with orientations of a shading gradient consistent with being lit from one of 24 simulated illumination directions. By positioning observers in different roll-tilt orientations relative to gravity and when supine, we were able to monitor change in the light-from-above prior (the orientation at which a shaded disk appears maximally convex). The results confirm previous findings that the light-from-above prior changes with body orientation relative to gravity. Interestingly, the results varied also with retinal orientation as well as an additional component that was approximately twice the frequency of retinal orientation. We use a modelling approach to show that the data are well predicted by summing retinal orientation with cross-multiplied utricle and saccule signals of the vestibular system, yielding gravity-dependent biases in the ability to extract shape-from-shading. We conclude that priors such as light coming from above appear to be constantly updated by neural processes that monitor self-orientation to achieve optimal object recognition over moderate deviations from upright posture at the cost of poor recognition when extremely tilted relative to gravity.

Snowboarding, along with Alpine skiing, is one of two most popular winter sports. While there are many studies on the mechanical conditions of movement in skiing, there is a lack of studies analyzing the forces affecting snowboarders. The difference in body orientation between snowboarding and skiing means that applying the same biomechanical rules to both sports is unjustified and a separate analysis is needed. The most difficult aspect of snowboarding is maintaining the correct body balance which is dependent on the directions and magnitudes of external forces and their torques. Therefore, the aim of this study was to analyze the forces that affect a snowboarder on the slope and the effects of these forces on the maintenance of a stable body posture. The research method used in the work is based on the theoretical analysis of physical phenomena that occur during riding on the snowboard. The study describes the biomechanical conditions that allow the snowboarder to maintain an upright posture when standing and moving, as well as the forces that initiate movement and decelerate the snowboarder. The physical forces that appear when moving forward and along an arc are analyzed, as are the mechanical interdependences that enable effective snowboarding. Knowing the rules of forces action is the best method for understanding how a snowboarder move and keep the balance on a slope. The application of theoretical knowledge should improve not only the self-confidence and effectiveness of the snowboarders but also the safety of their riding.

Purpose: Visual and proprioceptive cues are important for body orientation to maintain correct posture. This study investigated the effects of exercise training on subjective visual, postural, and haptic perception of verticality in patients with scoliosis. Subjects and Methods: Thirty-two female adolescents with moderate idiopathic scoliosis were randomly allocated to Core Stabilization Exercise (CSE), Body Awareness, or Traditional Exercise (TE) groups. Each group completed a 1-hour supervised program, two days per week for 10weeks while continuing to wear spinal braces. Perceptual visual, postural, and haptic estimates were assessed before and after treatment. Results: Subjective visual vertical perception only improved in the awareness group. Subjective visual horizontal perception, postural vertical perception, total postural perception scores, total haptic perception scores, and haptic perception 45 degrees to the right were significantly improved in the stabilization and awareness groups. For the 60 degrees right and 60 degrees left postural perception parameters, as well as the 45 degrees left haptic perception parameters, perception improved only in the stabilization group. No improvement was observed in the traditional group. Conclusion: Improvements in visual, postural, and haptic verticality perception within the stabilization exercise training and Basic Body Awareness group treatment suggest the addition of these exercise methods for the treatment of idiopathic scoliosis to improve internal body orientation.

Horizontal force-velocity (F-V) profiling is a strategy to assess athletes’ individual performance capabilities during sprinting. This study investigated the acute changes in F-V profiles during sp...

To internally estimate gravitational direction and body orientation, the central nervous system considers several sensory inputs from the periphery and prior knowledge of gravity. It is hypothesized that the modulation of visual inputs, supplying indirect information of gravity, affects the prior knowledge established internally by other sensory inputs from vestibular and somatosensory systems, leading to the alteration of perceived body orientation relative to gravity. In order to test the hypothesis, we examined the effect of presenting a visual motion stimulus during a whole-body static tilt on the subsequent evaluation of the perceived postural vertical. Fifteen subjects watched a target moving along the body longitudinal axis directing from head to feet with constant downward acceleration (CA condition) or constant velocity (CV condition), or they did not receive any visual stimulation (NV condition) during the whole-body static tilt. Subsequently, the direction of the subjective postural vertical (SPV) was evaluated. The result showed that the SPV in the CA condition was significantly tilted toward the direction of the preceding tilt compared to that in the NV condition while those in the CV and NV conditions were not significantly different. The present result suggests that dynamic visual motion along body longitudinal axis with downward acceleration can modulate prior knowledge of gravity, and in turn this affects the perception of body verticality.

Body orientation with respect to the direction of gravity changes when we lean forward from upright standing. We tested the hypothesis that during upright standing, the nervous system specifies the referent body orientation that defines spatial thresholds for activation of multiple muscles across the body. To intentionally lean the body forward, the system is postulated to transfer balance and stability to the leaned position by monotonically tilting the referent orientation, thus increasing the activation thresholds of ankle extensors and decreasing their activity. Consequently, the unbalanced gravitational torque would start to lean the body forward. With restretching, ankle extensors would be reactivated and generate increasing electromyographic (EMG) activity until the enhanced gravitational torque would be balanced at a new posture. As predicted, vestibular influences on motoneurons of ankle extensors evaluated by galvanic vestibular stimulation were smaller in the leaned compared with the upright position, despite higher tonic EMG activity. Defacilitation of vestibular influences was also observed during forward leaning when the EMG levels in the upright and leaned position were equalized by compensating the gravitational torque with a load. The vestibular system is involved in the active control of body orientation without directly specifying the motor outcome. Corticospinal influences originating from the primary motor cortex evaluated by transcranial magnetic stimulation remained similar at the two body postures. Thus, in contrast to the vestibular system, the corticospinal system maintains a similar descending facilitation of motoneurons of leg muscles at different body orientations. The study advances the understanding of how body orientation is controlled.NEW & NOTEWORTHY The brain changes the referent body orientation with respect to gravity to lean the body forward. Physiologically, this is achieved by shifts in spatial thresholds for activation of ankle muscles, which involves the vestibular system. Results advance the understanding of how the brain controls body orientation in the gravitational field. The study also extends previous evidence of empirical control of motor function, i.e., without the reliance on model-based computations and direct specification of motor outcome.

Purpose: To compare mechanical properties of overground sprint running in elite rugby union and rugby league athletes. Methods: Thirty elite rugby code (15 rugby union and 15 rugby league) athletes participated in this cross-sectional analysis. Radar was used to measure maximal overground sprint performance over 20 or 30 m (forwards and backs, respectively). In addition to time at 2, 5, 10, 20, and 30 m, velocity-time signals were analyzed to derive external horizontal force–velocity relationships with a recently validated method. From this relationship, the maximal theoretical velocity, external relative and absolute horizontal force, horizontal power, and optimal horizontal force for peak power production were determined. Results: While differences in maximal velocity were unclear between codes, rugby union backs produced moderately faster split times, with the most substantial differences occurring at 2 and 5 m (ES 0.95 and 0.86, respectively). In addition, rugby union backs produced moderately larger relative horizontal force, optimal force, and peak power capabilities than rugby league backs (ES 0.73−0.77). Rugby union forwards had a higher absolute force (ES 0.77) despite having ~12% more body weight than rugby league forwards. Conclusions: In this elite sample, rugby union athletes typically displayed greater short-distance sprint performance, which may be linked to an ability to generate high levels of horizontal force and power. The acceleration characteristics presented in this study could be a result of the individual movement and positional demands of each code.

On land, body sway during stance becomes coupled with imposed oscillations of the illuminated environment or of the support surface. This coupling appears to have the function of stabilizing the body relative to the illuminated or inertial environment. In previous research, the stimulus has been limited to motion in a single axis. Little is known about our ability to couple postural activity with complex, multi-axis oscillations. On a ship at sea, we evaluated postural activity using measures of body movement, as such, and we separately evaluated a direct measure of coupling between body movement and ship motion. Participants were tested while facing fore-aft and athwartship. We compared postural activity between participants who had been seasick at the beginning of the voyage and those who had not. Coupling of postural activity with ship motion differed between body axes as a function of body orientation relative to the ship. In addition, coupling differed between participants who had been seasick at the beginning of the voyage and those who had not. We discuss the results in terms of implications for general theories of postural control, and for prediction of susceptibility to seasickness in individuals.

Sensory information from the environment is used for body orientation and maintaining posture for effective movement, and the effects of specific senses on orientation and posture can be tested by removing input. In the present study, field dependence was used to evaluate the importance of vision in the perception of verticality when an upside-down posture was adopted under water. Eleven female synchronized swimmers at the French national level were participants. These swimmers were assessed for field dependence and all of them attempted to orient to the vertical with different types of sensory disturbance (eyes closed, opaque goggles, noiseless environment). Kinematic analyses of body inclination were conducted under the different conditions of sensory disturbance. Participants who were more field-dependent aligned their posture more accurately with the gravitational vertical than those who were more field-independent when the tactile afferents from the thighs are blocked.

Background Astronauts' orientation preferences tend to correlate with their susceptibility to space motion sickness (SMS). Orientation preferences appear universally, since variable sensory cue priorities are used between individuals. However, SMS susceptibility changes after proper training, while orientation preferences seem to be intrinsic proclivities. The present study was conducted to investigate whether orientation preferences change if susceptibility is reduced after repeated exposure to a virtual reality (VR) stimulus environment that induces SMS. Methods A horizontal supine posture was chosen to create a sensory context similar to weightlessness, and two VR devices were used to produce a highly immersive virtual scene. Subjects were randomly allocated to an experimental group (trained through exposure to a provocative rotating virtual scene) and a control group (untrained). All subjects' orientation preferences were measured twice with the same interval, but the experimental group was trained three times during the interval, while the control group was not. Results Trained subjects were less susceptible to SMS, with symptom scores reduced by 40%. Compared with untrained subjects, trained subjects' orientation preferences were significantly different between pre- and posttraining assessments. Trained subjects depended less on visual cues, whereas few subjects demonstrated the opposite tendency. Conclusion Results suggest that visual information may be inefficient and unreliable for body orientation and stabilization in a rotating visual scene, while reprioritizing preferences for different sensory cues was dynamic and asymmetric between individuals. The present findings should facilitate customization of efficient and proper training for astronauts with different sensory prioritization preferences and dynamic characteristics.Chen W, Chao J-G, Zhang Y, Wang J-K, Chen X-W, Tan C. Orientation preferences and motion sickness induced in a virtual reality environment. Aerosp Med Hum Perform. 2017; 88(10):903-910.

The aim of the present study was to examine the modification of postural symmetry during quiet standing using a sensorimotor adaptation paradigm. A group of neurologically typical adult participants performed a visually guided mediolateral (left-right) weight shifting task requiring precise adjustments in body orientation. During one phase of the task, the visual feedback of center of pressure (COP) was systematically biased toward the left or the right, requiring an adjustment in posture to compensate. COP during quiet standing without visual feedback was examined prior to and immediately following the sensorimotor adaptation procedure, in order to observe whether compensatory adjustments in postural control resulting from the visual-feedback manipulation would transfer to the control of whole-body COP during quiet standing. Results showed that the sensorimotor adaptation procedure induced a small but reliable compensatory change in the stance of participants, resulting in a change in postural symmetry and control that was found to persist even after normal visual feedback was restored.

To study body image disturbances in patients with typical meningioma of parietal-occipital localization before and after surgery.Twenty-three patients with the diagnosis of «typical meningioma of parietal-occipital localization» were studied. A battery of neuropsychological tests, dissociation methodology of «Image-I» and the method «Silhouette» were used.The body schema disorders were found in patients with meningioma of parietal-occipital area. There was the disturbance of the right-left orientation and position of body parts in space and in relation to each other as well as the disparity between the overall weight and height objective indicators and subjective perceptions of the body. After surgery, the body orientation was significantly improved. The distinct differentiation of the position of body parts relative to one another, adequate correlation between the position of two hands and unerring left-right orientation were seen. Perceptions of the body became more adequate for the number of body parts and their size, but the person's own ideas about the constitution as a whole remained inadequate.Цель исследования. Изучение нарушений схемы тела у больных с типичной менингиомой теменно-затылочной области до и после оперативного вмешательства. Материал и методы. Обследовали 23 больных с диагнозом 'типичная менингиома теменно-затылочной локализации'. Были использованы комплекс нейропсихологических проб, методика исследования диссоциации 'образа-Я', методика 'Силуэт'. Результаты и заключение. При менингиомах теменно-затылочной области выявлены нарушение схемы тела, проявляющееся в расстройстве право-левой ориентации и нарушении положения частей тела в пространстве и относительно друг друга, а также несоответствие объективных весо-ростовых показателей и субъективных представлений о своем теле. После оперативного вмешательства ориентация в собственном теле значимо улучшилась, что проявлялось в четкой дифференцировке положения частей тела относительно друг друга, адекватном соотнесении положения кистей двух рук, а также безошибочной право-левой ориентации. Представления о своем теле становились более адекватными в отношении количества частей тела и их размеров, однако представления о собственном телосложении в целом оставались неадекватными.Цель исследования. Изучение нарушений схемы тела у больных с типичной менингиомой теменно-затылочной области до и после оперативного вмешательства. Материал и методы. Обследовали 23 больных с диагнозом «типичная менингиома теменно-затылочной локализации». Были использованы комплекс нейропсихологических проб, методика исследования диссоциации «образа-Я», методика «Силуэт». Результаты и заключение. При менингиомах теменно-затылочной области выявлены нарушение схемы тела, проявляющееся в расстройстве право-левой ориентации и нарушении положения частей тела в пространстве и относительно друг друга, а также несоответствие объективных весо-ростовых показателей и субъективных представлений о своем теле. После оперативного вмешательства ориентация в собственном теле значимо улучшилась, что проявлялось в четкой дифференцировке положения частей тела относительно друг друга, адекватном соотнесении положения кистей двух рук, а также безошибочной право-левой ориентации. Представления о своем теле становились более адекватными в отношении количества частей тела и их размеров, однако представления о собственном телосложении в целом оставались неадекватными.

The Kinect v2 sensor may be a cheap and easy to use sensor to quantify gait in clinical settings, especially when applied in set-ups integrating multiple Kinect sensors to increase the measurement volume. Reliable estimates of foot placement locations are required to quantify spatial gait parameters. This study aimed to systematically evaluate the effects of distance from the sensor, side and step length on estimates of foot placement locations based on Kinect’s ankle body points. Subjects (n = 12) performed stepping trials at imposed foot placement locations distanced 2 m or 3 m from the Kinect sensor (distance), for left and right foot placement locations (side), and for five imposed step lengths. Body points’ time series of the lower extremities were recorded with a Kinect v2 sensor, placed frontoparallelly on the left side, and a gold-standard motion-registration system. Foot placement locations, step lengths, and stepping accuracies were compared between systems using repeated-measures ANOVAs, agreement statistics and two one-sided t-tests to test equivalence. For the right side at the 2mdistance from the sensor we found significant between-systems differences in foot placement locations and step lengths, and evidence for nonequivalence. This distance by side effect was likely caused by differences in body orientation relative to the Kinect sensor. It can be reduced by using Kinect’s higher-dimensional depth data to estimate foot placement locations directly from the foot’s point cloud and/or by using smaller inter-sensor distances in the case of a multi-Kinect v2 set-up to estimate foot placement locations at greater distances from the sensor.

Individuals with a positive body image appreciate their bodies, hold an internal perspective of their bodies, and are satisfied with the functionality of their bodies. Research shows that positive body image is more complex than the absence of body dissatisfaction. Although exercise reduces women's body dissatisfaction, very little research has explored how, or even whether, exercise is associated with positive body image. Therefore, we examined whether exercise frequency was positively related to three aspects of positive body image (body appreciation, internal body orientation, and functional body satisfaction) among 321 college women. Appearance-based exercise motivation (the extent exercise is pursued to influence weight or shape) was hypothesized to moderate these associations. Hierarchical moderated regression analyses showed that exercise frequency was related to higher positive body image, but high levels of appearance-based exercise motivation weakened these relationships. Thus, messages promoting exercise need to de-emphasize weight loss and appearance for positive body image.

Balance control can be interpreted as a combination of state feedback control with optimal state estimation. In this framework, state estimation uses an internal model of body and sensor dynamics to process sensory information and determine body orientation. The aim of this study was to assess the ability of the brain to create accurate state estimation when the congruence between sensory information was altered. Participants stood upright on a force platform with a monitor directly in front of them at eye level displaying their center of pressure (CP) position in real-time. When a target appeared on the monitor, participants had to move their CP as fast and as accurately as possible within the target. Voluntary balance pointing movements were made with the head either straight or rotated about the trunk, and mapping directions of the CP were changed on the basis of experimental conditions. Manipulating the sensory information congruency caused less accurate state estimation of the body motion leading to larger signed and absolute angular errors and a greater area of the final CP position were measured. These results suggest that performing head-centered to trunk-centered sensorimotor transformation reduces the accuracy in the state estimation of body motion during a balance pointing task.

On land, the spatial magnitude of postural sway (i.e., the amount of sway) tends to be greater when participants look at the horizon than when they look at nearby targets. By contrast, on ships at sea, the spatial magnitude of postural sway in young adults has been greater when looking at nearby targets and less when looking at the horizon. Healthy aging is associated with changes in the movement patterns of the standing body sway, and these changes typically are interpreted in terms of age-related declines in the ability to control posture. To further elucidate the mechanisms associated with these changes we investigated control of posture in a setting that poses substantial postural challenges; standing on a ship at sea. In particular, we explored postural sway on a ship at sea when older adults looked at the horizon or at nearby targets. We evaluated the kinematics of the center of pressure in terms of spatial magnitude (i.e., the amount of sway) and multifractality (a measure of temporal dynamics). We found that looking at the horizon significantly affected the multifractality of standing body, but did not systematically influence the spatial magnitude of sway. We discuss the results in terms of age-related changes in the perception and control of dynamic body orientation.

We used eye-tracking technique to examine gaze shifts of 9-, 16-, and 24-month-old infants who were presented with still images of a conversation between two individuals facing each other or turning away from each other. The results showed that body orientation, as measured by the face-to-face effect, is sufficient to provide infants with crucial information about others' social engagement.

Undergraduate women ( N = 143) completed self-reports on exercise behavior, body orientation, body appreciation, and body-related talk. Results showed that conversations about weight loss/dieting and conversations about exercise differentially predicted body appreciation. Importantly, multiple regression analyses showed that the relationship between talk type and body appreciation was explained by the object–process dichotomy: Conversations about exercise oriented women to consider what their bodies can do which, in turn, predicted appreciation of one’s body. In contrast, the relationship between conversations about weight loss/dieting and body appreciation was mediated by negative attitudes about one’s body but not by an object orientation.

INTRODUCTION: To flip a switch "down," our motor system can normally rely on concordant visual, gravitational, and egocentric cues about the vertical. However, divers must sometimes perform this task while visual cues are limited and gravitational cues are misaligned with egocentric cues. Astronauts must also flip switches "down" in absence of gravitational cues. Our study evaluates this ability using a laboratory simulation. METHODS: The subjects were 24 healthy volunteers who were blindfolded, tilted into different angles of roll, and asked to silence an alarm by flipping a switch "down." The switch was constructed such that it could be flipped in any direction in the subjects' frontal plane. RESULTS: Two subjects deflected the switch in accordance with the direction of gravity, irrespective of their body orientation. Twenty subjects deflected it in accordance with their body orientation, irrespective of the direction of gravity. The remaining two persons could not be classified unequivocally. Notably, some egocentric responders deflected the rod consistently toward their feet, but others deflected it consistently toward other parts of their body. DISCUSSION: Since our findings disagree with perceptual studies where gravitational rather than egocentric cues predominated in the absence of vision, we posit that perception and action may access distinct internal representations of the vertical. On the practical side, our findings indicate that designers of spaceflight and underwater equipment should not rely on divers' intuitive knowledge on how to flip a switch "down." Bock O, Bury N. Flipping a switch "down" when not aligned with the gravitational vertical. Aerosp Med Hum Perform. 2016; 87(10):838-843. Language: en

The impairment of the horizontal is caused by elevation of the heel of the foot from the ground. Receptors in the soles of the feet provide a mapping of body orientation to the upright, and is identical to Mittelstaedt's idiotropic tendency. Initiation of gait wearing flat shoes without elevation of the heel is sufficient to change to a truthful horizontal. Using flat shoes increases neurogenesis and leads to a decreased frequency of diseases of the nervous system.

The ability to localize moving joints of a person in action is crucial for interacting with other people in the environment. However, it remains unclear how the visual system encodes the position of joints in a moving body. We used a paradigm based on a well-known phenomenon, the flash-lag effect, to investigate the mechanisms underlying joint localization in bodily movements. We first found that observers perceived a strong flash-lag effect in biological motion: when a briefly-flashed dot was presented physically in perfect alignment with a continuously moving limb, the flash dot was perceived to lag behind the position of the moving joint. Importantly, our study revealed that for familiar forward walking actions, the strength of the flash-lag effect for a joint depends on body orientation. Specifically, observing a walker with a natural body orientation (i.e., upright) yielded a significantly stronger flash-lag effect for the critical foot joint than did viewing an inverted walker. In contrast, the hand joint showed a weaker flash-lag effect in the upright walker than the inverted walker. These findings suggest that the impact of body orientation on encoding joint locations depended on body part. Furthermore, we found that action familiarity modulates the impact of body orientation on the flash-lag effect. Body orientation impacted location encoding in familiar forward walking actions, but not in unfamiliar actions (e.g., backward walking, jumping-jack). Simulation results showed that generic motion mechanisms, such as the temporal averaging model, cannot fully account for these empirical findings regarding the flash-lag effect in biological motion. The present study provides compelling evidence that action processing interacts with position processing to localize the moving joints in whole-body actions, and that this influence depends on body orientation and familiarity of actions.

International audience; Objective This paper aims to provide some practical recommendations to reduce eye lens dose for workers exposed to X-rays in interventional cardiology and radiology and also to propose an eye lens correction factor when lead glasses are used. Methods Monte Carlo simulations are used to study the variation of eye lens exposure with operator position, height and body orientation with respect to the patient and the X-ray tube. The paper also looks into the efficiency of wraparound lead glasses using simulations. Computation results are compared with experimental measurements performed in Spanish hospitals using eye lens dosemeters as well as with data from available literature. Results Simulations showed that left eye exposure is generally higher than the right eye, when the operator stands on the right side of the patient. Operator height can induce a strong dose decrease by up to a factor of 2 for the left eye for 10-cm-taller operators. Body rotation of the operator away from the tube by 45°–60° reduces eye exposure by a factor of 2. The calculation-based correction factor of 0.3 for wraparound type lead glasses was found to agree reasonably well with experimental data. Conclusions Simple precautions, such as the positioning of the image screen away from the X-ray source, lead to a significant reduction of the eye lens dose. Measurements and simulations performed in this work also show that a general eye lens correction factor of 0.5 can be used when lead glasses are worn regardless of operator position, height and body orientation. © 2016 Associazione Italiana di Fisica Medica

Background. Visual vertical (VV) measurement provides information about spatial cognition and is now part of postural disorders assessment. Guidelines for clinical VV measurement after stroke remain to be established, especially regarding the orientation settings for patients who do not sit upright. Objectives. We analyzed the need to control body orientation while patients estimate the VV. Methods. VV orientation and variability were assessed in 20 controls and 36 subacute patients undergoing rehabilitation after a first hemisphere stroke, in 3 settings: body not maintained (trunk and head free), partially maintained (trunk maintained, head free), or maintained (trunk and head). VV was analyzed as a function of trunk and head tilt, also quantified. Results. Trunk and head orientations were independent. The ability to sit independently was affected by a tilted trunk. The setting had a strong effect on VV orientation and variability in patients with contralesional trunk tilt (n = 11; trunk orientation −18.4 ± 11.7°). The contralesional VV bias was severe and consistent under partially maintained (−8.4 ± 5.2°) and maintained (−7.8 ± 3.5°) settings, whereas various individual behaviors reduced the mean bias under the nonmaintained setting (−3.6 ± 9.3°, P < .05). VV variability was lower under the maintained (1.5 ± 0.2°) than nonmaintained (3.7 ± 0.4°, P < .001) and partially maintained (3.6 ± 0.2°, P < .001) settings. In contrast, setting had no effect in patients with satisfactory postural control in sitting. Conclusion. Subject setting improves VV measurement in stroke patients with postural disorders. Maintaining the trunk upright enhances the validity of VV orientation, and maintaining the head upright enhances the validity of within-subject variability. Measuring VV without any body maintaining is valid in patients with satisfactory balance abilities.

After a period of stepping on a rotating platform, blindfolded subjects demonstrate a tendency to unconsciously turn when stepping in place, an after-effect known as podokinetic after-rotation (PKAR). Recent studies have also reported a change in postural orientation following the adaptive period and have suggested that this is causally related to PKAR. Here, we assess changes in trunk orientation following platform adaptation and determine their relationship to PKAR. Specifically, we determine whether a reorganized standing posture causes PKAR. Ten subjects stepped on a platform rotating at 60°/s for 10 min, with a cadence of 100 steps/min. Following adaptation, a significant PKAR response was seen, with a mean yaw rotation velocity of 6.0 ± 2.2°/s. In addition to this dynamic after-effect, there was a significant twist of the trunk with respect to the feet when standing still (6.9° ± 4.5°; mean ± SD), confirming the presence of a postural reorientation after-effect. However, the magnitudes of the two after-effects did not correlate (r = 0.06, p = 0.87). Furthermore, in a second experiment, a prolonged passive twist of the trunk was used to induce postural reorientation. However, in this case, PKAR was not induced. These results demonstrate that PKAR is not an automatic consequence of reorganized standing posture.

The aim of this study was to determine the thresholds for perception of tilt and translation using 3 motion/tilt profile paradigms. Healthy subjects were submitted to the following: 1) unilateral and bilateral eccentric rotations (centrifugation), 2) whole body translatory decelerations opposite to the movement direction while seated on a linear sled, and 3) discrete slow velocity platform tilts. Subjects were instructed to verbally indicate the perceived direction of tilt or translation. Fifteen healthy subjects (12 male and 3 female subjects, 18-31 yr) without any history or evidence of any ophthalmologic or neuro-otologic disorder participated in this study. Our results from unilateral centrifugation indicate a threshold for body tilt perception of approximately 2 degrees with a substantial interindividual range (1.9-5.6 degrees, 52% interindividual and 34% intraindividual variability), which, to our interpretation, mainly depends on otolithic function. Tilt perception during whole body decelerations and discrete platform tilts mainly depends on somatosensory information, showing the dominant role of the somatosensory system for the perception of body orientation. Thus, tilt sensations during eccentric rotations seems to be a promising tool for the evaluation of utricular dysfunction.

In two experiments, the ability to use multisensory information (haptic information, provided by lightly touching a stationary surface, and vision) for quiet standing was examined in typically developing (TD) children, adults, and in seven-year-old children with Developmental Coordination Disorder (DCD). Four sensory conditions (no touch/no vision, with touch/no vision, no touch/with vision, and with touch/with vision) were employed. In experiment 1, we tested four-, six- and eight-year-old TD children and adults to provide a developmental landscape for performance on this task. In experiment 2, we tested a group of seven-year-old children with DCD and their age-matched TD peers. For all groups, touch robustly attenuated standing sway suggesting that children as young as four years old use touch information similarly to adults. Touch was less effective in children with DCD compared to their TD peers, especially in attenuating their sway velocity. Children with DCD, unlike their TD peers, also benefited from using vision to reduce sway. The present results suggest that children with DCD benefit from using vision in combination with touch information for standing control possibly due to their less well developed internal models of body orientation and self-motion. Internal model deficits, combined with other known deficits such as postural muscles activation timing deficits, may exacerbate the balance impairment in children with DCD.

Technique and energy saving are two variables often considered as important for performance in cycling and related to each other. Theoretically, excellent pedalling technique should give high gross efficiency (GE). The purpose of the present study was to examine the relationship between pedalling technique and GE. 10 well-trained cyclists were measured for GE, force effectiveness (FE) and dead centre size (DC) at a work rate corresponding to ~75% of VO2max during level and inclined cycling, seat adjusted forward and backward, at three different cadences around their own freely chosen cadence (FCC) on an ergometer. Within subjects, FE, DC and GE decreased as cadence increased (p

Dizziness is a nonspecific term that refers to various abnormal sensations of body orientation in space; patients often find these sensations difficult to describe. The prevalence of dizziness in the community ranges from 1.8% among young adults to over 30% among the elderly. Yearly consultation

Reaching movements are initiated by activity of the prime mover, i.e. the first activated arm muscle. We aimed to investigate the relationship between prime mover activity and kinematics of reaching in typically developing (TD) infants in supine and sitting position.Fourteen infants were assessed at 4 and 6 months during reaching in supine and supported sitting. Kinematics and EMG-activity of deltoid, pectoralis major, biceps (BB) and triceps brachii were recorded. Kinematic analysis focused on number of movement units (MUs) and transport MU (MU with longest duration).Prime mover use was variable, but at 6 months a dominance of BB emerged in both testing conditions. Kinematics were also variable, but with increasing age the number of MU decreased and the relative proportion of the transport MU increased. BB as prime mover at 6 months was related to a larger transport MU.Conclusion: Between 4 and 6 months BB prime mover dominance emerges which is related to relatively efficient reaching characteristics. (C) 2009 Elsevier Inc. All rights reserved.

BACKGROUND On land, the distance and angle between the feet in side-by-side stance tend to have characteristic values. Ship motion mandates changes in the control of stance, but there have been no direct assessments of how stance width and angle are controlled at sea. We predicted that participants would adopt a wider stance at sea. METHOD On two ships, we measured experienced crewmembers' stance width and stance angle during quiet stance when facing forward and when facing athwartship. Each ship was 84 m long and displaced 3500 tons. Measurements were repeated over consecutive days at sea. For one ship, we tested crew-members on land prior to the cruise. RESULTS On land, stance width (mean = 19.0 cm) and stance angle (mean = 16.19 degrees) were similar to previous reports. At sea, stance width tended to be greater than on land. When facing athwartship on Ship B, changes in stance width across days were correlated with changes in motion of the ship in its surge axis (r = 0.968). Stance angle at sea did not differ from stance angle on land. CONCLUSIONS The results suggest that preferred stance width is influenced by the fact of being at sea and by the sea state. These variations may be related to the efficiency of postural control on land and at sea. Future research should examine changes in stance width as novices acclimate to life at sea.

Recent research has shown that domestic dogs are particularly good at determining the focus of human attention, often outperforming chimpanzees and hand-reared wolves. It has been suggested that the close evolutionary relationship between humans and dogs has led to the development of this ability; however, very few other domestic species have been studied. We tested the ability of 36 domestic horses to discriminate between an attentive and inattentive person in determining whom to approach for food. The cues provided were body orientation, head orientation or whether the experimenters' eyes were open or closed. A fourth, mixed condition was included where the attentive person stood with their body facing away from the subjects but their head turned towards the subject while the inattentive person stood with their body facing the subject but their head turned away. Horses chose the attentive person significantly more often using the body cue, head cue, and eye cue but not the mixed cue. This result suggests that domestic horses are highly sensitive to human attentional cues, including gaze. The possible role of evolutionary and environmental factors in the development of this ability is discussed.

Body orientation provides an important cue to other individuals' focus of attention, particularly when one is viewing them at a distance. Single-cell recording in macaques has identified cells in the superior temporal sulcus that show a view-selective response to particular body orientations. Whether similar separable coding is found in humans is not known, and there is currently no functional account of the visual representation of seen body orientation. This study addressed this issue using visual adaptation. Experiment 1 demonstrated distinct channels that code left- and right-oriented bodies. Experiment 2 investigated whether the visual representation of body orientation is best accounted for by an opponent-coding system, which has been shown to account for the visual representation of facial identity, or by a multichannel system, which provides the optimal account of coding line orientation and direction of motion. Our results provide evidence for multichannel coding of seen body orientation, with separate channels (or neuronal populations) selectively tuned to different body directions.

We measured the change in subjective straight-ahead (SSA) as a function of time after vestibular stimulation. Blindfolded subjects were exposed to sudden stops after constant velocity (72°/s) z-axis rotation. They were then asked to open their eyes and continuously adjust the position of a laser spot to the position perceived as straight ahead (visual localization of SSA) immediately, or after a 10 s or 20 s delay following the sudden stop. The deviation of SSA increased to 20 s in the opposite direction of acceleration and then decreased gradually when the visual localization task was started immediately after sudden stops. The time courses changed systematically when the task was started after a delay of 10 s or 20 s following sudden stops: the initial increase component and maximum magnitude of the SSA deviation fell off with delay length, but the increase-decrease pattern was preserved. These delay effects on the time course of the SSA deviation might reflect that the velocity-to-orientation/position integrator for perception of body orientation in vestibular system might be inactivated temporarily during the delay period after vestibular stimulation without visual input.

This study was designed to determine whether tonic activity of selected muscles of patients with cerebral palsy changed in response to changes in orientation of the body in space. Surface electrodes measured electromyographic activity of the low-back extensor, hip adductor and ankle plantar-flexor muscles when the body was at 0 degree (upright) and 30 degrees (recline) relative to the vertical. Muscle activity did change in response to body orientation, and was less in the upright position.

International audience; We investigated the influence of gaze elevation on judging the possibility of passing under high obstacles during pitch body tilts, while stationary, in absence of allocentric cues. Specifically, we aimed at studying the influence of egocentric references upon geocentric judgements. Seated subjects, orientated at various body orientations, were asked to perceptually estimate the possibility of passing under a projected horizontal line while keeping their gaze on a fixation target and imagining a horizontal body displacement. The results showed a global overestimation of the possibility of passing under the line, and confirmed the influence of body orientation reported by Bringoux et al. (Exp Brain Res 185(4):673-680, 2008). More strikingly, a linear influence of gaze elevation was found on perceptual estimates. Precisely, downward eye elevation yielded increased overestimations, and conversely upward gaze elevation yielded decreased overestimations. Furthermore, body and gaze orientation effects were independent and combined additively to yield a global egocentric influence with a weight of 45 and 54%, respectively. Overall, our data suggest that multiple egocentric references can jointly affect the estimated possibility of passing under high obstacles. These results are discussed in terms of ``interpenetrability'' between geocentric and egocentric reference frames and clearly demonstrate that gaze elevation is involved, as body orientation, in geocentric spatial localization.

The different neural control systems involved in goal-directed vertebrate locomotion are reviewed. They include not only the central pattern generator networks in the spinal cord that generate the basic locomotor synergy and the brainstem command systems for locomotion but also the control systems for steering and control of body orientation (posture) and finally the neural structures responsible for determining which motor programs should be turned on in a given instant. The role of the basal ganglia is considered in this context. The review summarizes the available information from a general vertebrate perspective, but specific examples are often derived from the lamprey, which provides the most detailed information when considering cellular and network perspectives.

Many studies have demonstrated that the seated position is more effective in promoting reaching movements when compared with supine. The aim of this longitudinal study was to verify the effect of seated and supine positions on spatio-temporal parameters of reaching in 4-6-month-old infants. Four infants were observed during reaching trials in both positions. A total of 235 reaches were analyzed by using the 3D movement reconstruction. Our results showed that frequency of reaching and straightness index increased over age. Significant differences between the positions were observed at 4 months, when the frequency increased and the duration and deceleration time decreased in the seated position. There were no significant differences at 5 and 6 months. These findings suggest that young infants are able to change kinematical parameters of reaching to adapt themselves to intrinsic and extrinsic constraints (i.e. age and position).