Necessity of spatial pooling for the perception of heading in nonrigid environments.

Abstract

This study examined whether the perception of heading is determined by spatially pooling velocity information. Observers were presented displays simulating observer motion through a volume of 3-D objects. To test the importance of spatial pooling, the authors systematically varied the nonrigidity of the flow field using two types of object motion: adding a unique rotation or translation to each object. Calculations of the signal-to-noise (observer velocity-to-object motion) ratio indicated no decrements in performance when the ratio was .39 for object rotation and .45 for object translation. Performance also increased with the number of objects in the scene. These results suggest that heading is determined by mechanisms that use spatial pooling over large regions.

Integration Mechanisms for Heading Perception

“…The results reported here, together with previous findings (Andersen and Saidpour, 2002; Royden and Vaina, 2004; van den Berg, 1992; Warren et al, 1991), demonstrate the importance of spatiotemporal integration mechanisms for the accurate judgment of straight-trajectory heading. The involvement of spatial integration mechanisms in heading discrimination is supported by computational models (Beck et al, 2007; Longuet-Higgins and Prazdny, 1980; Perrone and Stone, 1998; Royden, 1997; Royden, 2002).…”

“…While previous psychophysical work reported the involvement of spatiotemporal mechanisms in optic flow perception (Andersen and Saidpour, 2002; Beck et al, 2007; Royden, 2002; Warren et al, 1991), it has not addressed specifically how the spatial and temporal information present within stimuli are utilized by the integration mechanisms during heading perception.…”

“…Since Gibson’s seminal study, psychophysical, physiological and theoretical studies have demonstrated that the pattern of optic flow plays an important role in computing heading (see Andersen and Saidpour, 2002; Britten and Van Wezel, 2002; Britten, 2008; Crowell and Banks, 1993; Grigo and Lappe, 1999; Koenderink and van Doorn, 1987; Li et al, 2009; Longuet-Higgins and Prazdny, 1980; Royden, 1997; Royden et al, 2006; Vaina, 1998; Warren et al, 1988; Warren et al, 1991). Psychophysical studies and theoretical models have shown that heading perception is robust under various conditions, including retinal eccentricity (Crowell and Banks, 1993), eye movements with small rotation rates (Lappe et al, 1999; Royden et al, 1992; Royden et al, 1994; Warren et al, 1991) and high levels of noise (Royden, 1997; van den Berg, 1992; Warren et al, 1991).…”

Impaired perception of self-motion (heading) in abstinent ecstasy and marijuana users

“…These models were motivated by neurophysiological studies (Duffy and Wurtz 1991;Saito et al 1986) that showed that area MST (medial superior temporal area of primate visual cortex) has cells that respond to large field expansion patterns by pooling the output of cells that respond to local velocities in area MT (middle temporal area of primate extrastriate visual cortex). More recently, Andersen and Saidpour (2002) demonstrated that the perception of heading by human observers required pooling local velocities over regions of at least an 8.5°visual angle. The necessity of spatially pooling velocities for the perception of heading can be contrasted to other high-level motion tasks that are based on local velocities.…”

Distinct visual motion processing impairments in aging and Alzheimer’s disease

“…In young people, the visual motion processing of naturalistically large stimuli is supported by spatial and temporal cue integration that influence direction [Graham and Robson 1987] [Fredericksen et al 1994] and speed discrimination [Andersen and Saidpour 2002]. Declines in motion coherence, created by the addition of random motion, impairs the processing of such stimuli [Zanker and Hupgens 1994].…”