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Humans, being highly social creatures, rely heavily on the ability to perceive what others are doing and to infer from gestures and expressions what others may be intending to do. These perceptual skills are easily mastered by most, but not all, people, in large part because human action readily communicates intentions and feelings. In recent years, remarkable advances have been made in our understanding of the visual, motoric, and affective influences on perception of human action, as well as in the elucidation of the neural concomitants of perception of human action. This article reviews those advances and, where possible, draws links among those findings. Acronyms and Definitions Apparent motion: perception of smooth motion from brief, successive exposures of static images Chameleon effect: tendency for people to mimic the actions of others without even knowing it Common coding principle: theory that perceiving and acting share common mental representations Dynamic noise: an array of randomly positioned dots that can camouflage perception of PL animations when the noise dots are sufficiently dense Event-related potential (ERP): electrical brain activity registered from the scalp Extrastriate body area (EBA): brain region activated when a person views a human body or body parts Functional magnetic resonance imaging (fMRI): widely used technique that reveals brain activation patterns based on hemodynamic responses to neural activity Inversion effect: difficulty of perceiving PL animations when they are shown upside down Kinematics: analysis of the motions of objects without regard to the forces producing them Mirror neurons: brain cells responsive when an animal engages in an activity or when it watches another animal engaged in that activity Point-light animations: biological activity portrayed by small light tokens (point lights) placed on the major body parts of an actor Positron emission tomography (PET): brain imaging technique that uses radioactively labeled tracers to allow visualization of active brain areas Spatiotemporal jitter: means of degrading perception of PL animations, where the relative timing and positions of the moving dots are perturbed Superior temporal sulcus (STS): region of the cortex the posterior portion of which contains neurons selectively responsive to human activity Template-matching model: theory that perception of biological motion results from concatenation of static views of the body Transcranial magnetic stimulation (TMS): technique producing a brief disruption of neural processing.
Introduction: We are required on a daily basis to estimate our position and motion in space by centrally combining noisy, incomplete, and potentially conflicting or ambiguous, information from both sensory sources (e.g. vestibular organs, visual, proprioceptive), and non-sensory sources (e.g. efferent copy, cognition)). This "spatial orientation" is normally subconscious, and information from multiple sense organs is automatically fused into perception. As late as the early nineteenth century, very little was known about the underlying mechanisms, and our understanding of some critical factors such as such as how the brain resolves the tilt-translation ambiguity is only now beginning to be understood. The otolith organs function like a three-axis linear accelerometer, responding to the vector difference between gravity and linear acceleration (GIF= g - a). How does the brain separate gravity from linear acceleration? How does the brain combine cues from disparate sensors to derive an overall perception of motion? What happens if these sensors provide conflicting information? Humans routinely perform balance tasks on a daily basis, sometimes in the absence of visual cues. The inherent complexity of the tasks is evidenced by the wide range of balance pathologies and locomotive difficulties experienced by people with vestibular disorders. Maintaining balance involves stabilizing the body's inverted pendulum dynamics where the center of rotation (at the ankles) is below the center of mass and the vestibular sensors are above the center of rotation (for example, swaying above the ground level or balancing during standing or walking). This type of swing motion is also encountered in most fixed-wing aircraft and flight simulators, where the pilot is above the center of roll. Swing motions where the center of mass and sensors are below the center of rotation are encountered on a child's swing, and in some high-wing aircraft and helicopters. Spatial orientation tasks requiring central integration of sensory information are ubiquitous in aerospace. Spatial disorientation, often triggered by unusual visual or flight conditions, is attributed to around 10% of aviation accidents, and many of these are fatal. Simulator training is a key factor in establishing the supremacy of instrument-driven flight information over vestibular and other human sensory cues in the absence of reliable visual information. It therefore becomes important to ensure that simulators re-create motion perceptions as accurately as possible. What cues can safely be ignored or replaced with analogous cues? How realistic and consistent must a visual scene be to maintain perceptual fidelity? Spatial orientation is also a critical human factor in spaceflight. Orientation and navigation are impaired by the lack of confirming gravitation cues in microgravity, as sensory cues are misinterpreted and generate the incorrect motion perceptions. These persist at least until the vestibular or central nervous system pathways adapt to the altered gravity environment, however human navigation never fully adapts to the three dimensional frame. There is a wealth of data describing the difficulties with balance, gait, gaze control, and spatial orientation on return to Earth. Post-flight ataxia (a neurological sign of gross incoordination of motor movements) is a serious concern for all returning space travelers for at least ten days. This would be an even more serious concern for newly arrived astronauts conducting operations extraterrestrial environments after a long space flight. What motion profiles in a lunar landing simulator on Earth will best prepare astronauts for the real task in an altered gravity environment? Far from being a problem restricted to a human operator, the aerospace systems themselves face the same challenge of integrating sensory information for navigation. Modeling how the brain performs multi-sensory integration has analogies to how aircraft and spacecraft perform this task, and in fact modelers have employed similar techniques. Thus, developments in modeling multi-sensory integration improve our understanding of both the operator and the vehicle. Specifically, this research is concerned with how human motion perception is affected during swing motion when vestibular information is incomplete or ambiguous, or when conflicting visual information is provided.
The Cambridge Handbook of Applied Perception Research covers core areas of research in perception with an emphasis on its application to real-world environments. Topics include multisensory processing of information, time perception, sustained attention, and signal detection, as well as pedagogical issues surrounding the training of applied perception researchers. In addition to familiar topics, such as perceptual learning, the Handbook focuses on emerging areas of importance, such as human-robot coordination, haptic interfaces, and issues facing societies in the twenty-first century (such as terrorism and threat detection, medical errors, and the broader implications of automation). Organized into sections representing major areas of theoretical and practical importance for the application of perception psychology to human performance and the design and operation of human-technology interdependence, it also addresses the challenges to basic research, including the problem of quantifying information, defining cognitive resources, and theoretical advances in the nature of attention and perceptual processes.
The Senses: A Comprehensive Reference, Second Edition, Seven Volume Set is a comprehensive reference work covering the range of topics that constitute current knowledge of the neural mechanisms underlying the different senses. This important work provides the most up-to-date, cutting-edge, comprehensive reference combining volumes on all major sensory modalities in one set. Offering 264 chapters from a distinguished team of international experts, The Senses lays out current knowledge on the anatomy, physiology, and molecular biology of sensory organs, in a collection of comprehensive chapters spanning 4 volumes. Topics covered include the perception, psychophysics, and higher order processing of sensory information, as well as disorders and new diagnostic and treatment methods. Written for a wide audience, this reference work provides students, scholars, medical doctors, as well as anyone interested in neuroscience, a comprehensive overview of the knowledge accumulated on the function of sense organs, sensory systems, and how the brain processes sensory input. As with the first edition, contributions from leading scholars from around the world will ensure The Senses offers a truly international portrait of sensory physiology. The set is the definitive reference on sensory neuroscience and provides the ultimate entry point into the review and original literature in Sensory Neuroscience enabling students and scientists to delve into the subject and deepen their knowledge. All-inclusive coverage of topics: updated edition offers readers the only current reference available covering neurobiology, physiology, anatomy, and molecular biology of sense organs and the processing of sensory information in the brain Authoritative content: world-leading contributors provide readers with a reputable, dynamic and authoritative account of the topics under discussion Comprehensive-style content: in-depth, complex coverage of topics offers students at upper undergraduate level and above full insight into topics under discussion
One of the major goals of this thesis is to investigate the extent to which correspondence noise, (i.e., the false pairing of dots in adjacent frames) limits motion detection performance in random dot kinematograms (RDKs). The performance measures of interest are Dmax and Dmin i.e., the largest and smallest inter-frame dot displacement, respectively, for which motion can be reliably detected. Dmax and threshold coherence (i.e., the smallest proportion of dots that must be moved between frames for motion to be reliably detected) in RDKs are known to be affected by false pairing or correspondence noise. Here the roles of correspondence noise and receptive field geometry in limiting performance are investigated. The range of Dmax observed in the literature is consistent with the current information-limit based interpretation. Dmin is interpreted in the light of correspondence noise and under-sampling. Based on the psychophysical experiments performed in the early parts of the dissertation, a model for correspondence noise based on the principle of receptive field scaling is developed for Dmax. Model simulations provide a good account of psychophysically estimated Dmax over a range of stimulus parameters, showing that correspondence noise and receptive field geometry have a major influence on displacement thresholds.