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Otmar Bock, Charles Worringham, and Sandi Dawson

Previous work has shown that amplitude and direction are two independently controlled parameters of aimed arm movements, and performance, therefore, suffers when they must be decomposed into Cartesian coordinates. We now compare decomposition into different coordinate systems. Subjects pointed at visual targets in 2-D with a cursor, using a two-axis joystick or two single-axis joysticks. In the latter case, joystick axes were aligned with the subjects’ body axes, were rotated by −45°, or were oblique (i.e., one axis was in an egocentric frame and the other was rotated by −45°). Cursor direction always corresponded to joystick direction. We found that compared with the two-axis joystick, responses with single-axis joysticks were slower and less accurate when the axes were oriented egocentrically; the deficit was even more pronounced when the axes were rotated and was most pronounced when they were oblique. This confirms that decomposition of motor commands is computationally demanding and documents that this demand is lowest for egocentric, higher for rotated, and highest for oblique coordinates. We conclude that most current vehicles use computationally demanding man–machine interfaces.

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Marlene Luis and Luc Tremblay

We aimed to determine if visual feedback use during aerial skills is more efficient at low angular head velocity (AHV; i.e., <350 deg/s) than at high AHV. Twelve experienced female acrobats performed 20 back tuck somersaults under four experimental conditions: full-vision (FV), vision at AHV below 350 deg/s (VBelow), vision at AHV above 350 deg/s (VAbove), and no-vision (NV). AHV was calculated in real time, and liquid crystal goggles were used to manipulate vision. Two gymnastics judges scored landing stability using a four-point scale. All vision conditions that allowed some vision yielded significantly better landing scores than in the NV condition. Furthermore, a nonparametric test revealed that VBelow yielded a better performance ranking than the FV condition. We conclude that visual feedback during a back tuck somersault is used for landing stability at all angular head velocities, but optimal feedback use occurs when there is retinal stability.

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Christopher C. Pagano and Michael T. Turvey

We report several experiments directed at the ability of humans to perceive the spatial orientation of occluded objects, to position an occluded limb relative to targets or directions in the environment, and to match the spatial orientations of occluded contralateral limbs. Results suggest that each of these abilities is lied to the inertial eigenvectors of each object or limb, which correspond to the object's or limb's principal axes of rotational inertia. Discussion focuses on the dynamic nature of proprioception, the importance of physical invariants for perception, and the relation of invariants to hypothesized frames of reference for proprioception and motor control. It is suggested that the detection of invariants revealed through movement is a major mechanism in kinesthetic perception involving intact limbs, neuropathic or anesthetized limbs, prosthetic devices, and hand-held tools and implements. The inertia tensor is identified as one such invariant.

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Rebecca Lytle

and target games, includes information on 13 different sports. The final chapter includes lessons to enhance head control, hand movements, spatial orientation, cycling, fitness, and a host of other pursuits to support health-related activity. The book ends with an appendix that provides resources for

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Konstantin Beinert, Katharina Deutsch, Sebastian Löscher, and Martin Diers

barrier for immediate effects. The stronger CJPS acuity improvement after real-time visual feedback of the neck measured with closed eyes highlights the importance of the eye-centered reference frame for spatial orientation of body segments for patients with neck pain. In line with this, Thompson and

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Julia Sargent and Antonio Calderón

predisposition and motivation toward learning spatial orientation in students using augmented reality. Aurasma application Students’ motivation toward the development of the task has been optimal. The use of Aurasma to develop spatial orientation was very positively valued by students. 2 Østerlie and Kjelaas

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Charline Madelaine, Nicolas Benguigui, and Michèle Molina

: position in space (distinguish the spatial orientation of different shapes), figure ground (identifying geometrical forms among intertwined forms), visual closure (mentally completing a dotted line drawing to find its shape), and form constancy (associating two identical forms with different size, color

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Stephen M. Glass, Christopher K. Rhea, Matthew W. Wittstein, Scott E. Ross, John P. Florian, and F.J. Haran

transition to a terrestrial environment. More importantly, the extent to which any observed changes are maladaptive for the terrestrial environment is unknown. Postural control is a commonly observed outcome in the assessment of sensorimotor function and spatial orientation. 17 In healthy adults and under

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Ian McGinnis, Justin Cobb, Ryan Tierney, and Anne Russ

recovery from concussion, both in athletic and general populations. 4 – 6 The vestibular system’s regulation of balance, spatial orientation, and gaze stability plays a key role in athletic tasks and many activities of daily living. Disruption of the vestibular system can exacerbate other symptoms of

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Robert Kennedy

descriptive spatial orientation. Meier’s exploration of idiomatic expression using bigram analysis is very instructive, demonstrating that certain pairings of words stand out as frequent adjacent pairings; some of these are semantically transparent, while others are more opaque, and their occurrence is only