Estimating Gesture Accuracy in Motion-Based Health Games

This manuscript details a technique for estimating gesture accuracy within the context of motion-based health video games using the MICROSOFT KINECT. We created a physical therapy game that requires players to imitate clinically significant reference gestures. Player performance is represented by the degree of similarity between the performed and reference gestures and is quantified by collecting the Euler angles of the player's gestures, converting them to a three-dimensional vector, and comparing the magnitude between the vectors. Lower difference values represent greater gestural correspondence and therefore greater player performance. A group of thirty-one subjects was tested. Subjects achieved gestural correspondence sufficient to complete the game's objectives while also improving their ability to perform reference gestures accurately.

Xinjiang’s geographies in motion

Starting from the idea that places are socially constructed, this essay explores how place is established and lived in Xinjiang by the members of the area’s two largest ethnicities, the Uyghur and the Han. This paper demonstrates that there are differences in the ways Han and Uyghur imagine and ‘live’ Xinjiang. At the same time it asserts that Uyghur and Han do not establish distinct spatial relationships just because of their ethnicity, but also to enhance ethnic solidarity and boundaries vis-à-vis the other. This essay also demonstrates that places are historically contingent, and it discusses the ways in which the influx of Han temporary migrants and settlers—and Han capital—has generated new layers of spatial meaning and new power differentials.

Perceptual learning in motion discrimination that generalizes across motion directions

When human subjects discriminate motion directions of two visual stimuli, their discrimination improves with practice. This improved performance has been found to be specific to the practiced directions and does not transfer to new motion directions. Indeed, such stimulus-specific learning has become a trademark finding in almost all perceptual learning studies and has been used to infer the loci of learning in the brain. For example, learning in motion discrimination has been inferred to occur in the visual area MT (medial temporal cortex) of primates, where neurons are selectively tuned to motion directions. However, such motion discrimination task is extremely difficult, as is typical of most perceptual learning tasks. When the difficulty is moderately reduced, learning transfers to new motion directions. This result challenges the idea of using simple visual stimuli to infer the locus of learning in low-level visual processes and suggests that higher-level processing is essential even in “simple” perceptual learning tasks.

Psychophysical evidence for fast region-based segmentation processes in motion and color.

Theories of image segmentation suggest that the human visual system may use two distinct processes to segregate figure from background: a local process that uses local feature contrasts to mark borders of coherent regions and a global process that groups similar features over a larger spatial scale. We performed psychophysical experiments to determine whether and to what extent the global similarity process contributes to image segmentation by motion and color. Our results show that for color, as well as for motion, segmentation occurs first by an integrative process on a coarse spatial scale, demonstrating that for both modalities the global process is faster than one based on local feature contrasts. Segmentation by motion builds up over time, whereas segmentation by color does not, indicating a fundamental difference between the modalities. Our data suggest that segmentation by motion proceeds first via a cooperative linking over space of local motion signals, generating almost immediate perceptual coherence even of physically incoherent signals. This global segmentation process occurs faster than the detection of absolute motion, providing further evidence for the existence of two motion processes with distinct dynamic properties.

Surréalisme Sous-L’Eau : science and surrealism in the early films and writings of Jean Painlevé

A French biologist who moved in Surrealist circles, Jean Painlevé began making films about underwater creatures in 1927, and by 1982 had created over two hundred films on a broad range of natural, scientific, and political subjects. His underwater films remain the most ethereal and poetic works in his oeuvre, and he specifically used cinema to capture the mystery and wonder of nature.