Images of illusory motion in primary visual cortex.
ABSTRACT Illusory motion can be generated by successively flashing a stationary visual stimulus in two spatial locations separated by several degrees of visual angle. In appropriate conditions, the apparent motion is indistinguishable from real motion: The observer experiences a luminous object traversing a continuous path from one stimulus location to the other through intervening positions where no physical stimuli exist. The phenomenon has been extensively investigated for nearly a century but little is known about its neurophysiological foundation. Here we present images of activations in the primary visual cortex in response to real and apparent motion. The images show that during apparent motion, a path connecting the cortical representations of the stimulus locations is filled in by activation. The activation along the path of apparent motion is similar to the activation found when a stimulus is presented in real motion between the two locations.
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ABSTRACT: Experiments that test perceptual illusions and movement perception have relied predominantly on observing participant response to screen-based phenomena. There are a number of inherent problems to this experimental method as it involves flicker, ignores depth perception and bypasses the proprioceptive system, in short it is psychophysically distinct from dynam- ic real life (veridical) perception. Indeed there still is much disagreement regarding perception of apparent (screen-based) motion despite the fact that we view it in a myriad of ways on an everyday basis. With the aim of furthering our understand- ing and evaluation of veridical movement perception, the team sought to develop a replicable technique that included embod- ied, multi-sensory perception but eliminated the screen. They approached this by taking time-based techniques from anima- tion and converting them to the spatial;; grouping static objects according to Gestalt principles, to create sequential visual cues that, when lit with projected light, demand selective attention. ␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣ ␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣he name Diasynchronoscope comes from combining diachronic, (the study of a phenomenon as it changes through time) with synchronous and scope (view). In being so named, it evokes the early animation simulators such as the phenakistoscope and the zoetrope, regarded as direct ancestors of the project in acting both as art objects and experimental media. This paper documents the creation of this new, experimental medium in choreo- graphed time and discusses its potential as a novel tool for investigating aesthetics in movement.Computational Aesthetics in Graphics, Visualization, and Imaging; 05/2012
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ABSTRACT: Illusory line motion (ILM) refers to a motion illusion in which a flash at one end of a bar prior to the bar's instantaneous presentation or removal results in the percept of motion. While some theories attribute the origin of ILM to attention or early perceptual mechanisms, others have proposed that ILM results from impletion mechanisms that reinterpret the static bar as one in motion. The current functional magnetic resonance imaging study examined participants while they made decisions about the direction of motion in which a bar appeared to be removed. Preceding the instantaneous removal of the bar with a flash at one end resulted in a motion percept away from the flash. If this flash and the bar's removal overlapped in time, it appeared that the bar was removed towards the flash (reverse ILM). Independent of the motion type, brain responses indicated activations in areas associated with motion (MT+), endogenous and exogenous attention (intraparietal sulcus, frontal eye fields, and ventral frontal cortex), and response selection (ACC). ILM was associated with lower percept scores and higher activations in ACC relative to real motion, but no differences in shape-selective areas emerged. This pattern of brain activation is consistent with the attentional gradient model or bottom-up accounts of ILM in preference to impletion.PLoS ONE 01/2014; 9(1):e87595. · 3.53 Impact Factor
Article: Seeing Motion and Apparent Motion[Show abstract] [Hide abstract]
ABSTRACT: In apparent motion experiments, participants are presented with what is in fact a succession of two brief stationary stimuli at two different locations, but they report an impression of movement. Philosophers have recently debated whether apparent motion provides evidence in favour of a particular account of the nature of temporal experience. I argue that the existing discussion in this area is premised on a mistaken view of the phenomenology of apparent motion and, as a result, the space of possible philosophical positions has not yet been fully explored. In particular, I argue that the existence of apparent motion is compatible with an account of the nature of temporal experience that involves a version of direct realism. In doing so, I also argue against two other claims often made about apparent motion, viz. that apparent motion is the psychological phenomenon that underlies motion experience in the cinema, and that apparent motion is subjectively indistinguishable from real motion.European Journal of Philosophy 09/2012;