The utility of motion parallax information for the perception and control of heading.

Abstract

Two experiments in which participants were given control over the direction of computer-simulated self-motion were conducted. Environments were designed to evaluate the functionality of simple and multiple motion parallax as well as a separation ratio (sigma; indexing the separation of 2 objects in depth) for the perception and control of heading. Results provide a 1st indication of optimizing performance in the top end of the global optical flow velocity range available during human bipedal self-motion. The introduction of sigma, developed to explain performance improvements with decreasing distance to the target, was able to account for most of the performance differences among all simulated environments. The rate of change in horizontal optical separation between at least 2 discontinuities was identified as a likely candidate for the optical foundation of the perception and control of heading during target approach.

Active heading control in simulated flight based on vertically extended contours

“…The present results extend the literature on heading perception (see, e.g., Li & Warren, 2000;Royden et al, 1994; see the review by Warren, 1998) into the domain of active heading control (see also, e.g., Frey & Owen, 1999;Li & Warren, 2002;Rushton et al, 1999), which is important given that heading perception and heading control may be mediated by anatomically and functionally distinct cortical systems (see, e.g., Aglioti et al, 1995;Bridgeman et al, 2000;Goodale et al, 1991; see the review by Milner & Goodale, 1995). Consistent with Li and Warren (2002), we found that, provided that motion parallax information is available, retinal flow is sufficient for the control of self-motion even when extraretinal information is absent.…”

“…In one of the few, Rushton, Harris, and Wann (1999) reported that depth information (provided either by static perspective cues or by binocular disparity) did not improve active heading control. In another, Frey and Owen (1999) found that adding motion parallax cues produced little or no improvement in active heading control. However, as discussed by Li and Warren (2002), the simulated-rotation rates in those studies were relatively low (less than 0.6º/sec).…”

Seeking one’s heading through eye movements

“…Ultimately, these theories appeal to the motion-sensitive receptive fields of cortical cells (e.g., Hildreth, 1992;Perrone & Stone, 1994;Rieger & Lawton, 1985). Some, following Gibson (1979), look specifically for the efficacy of radial expansion patterns (Duffy & Wurtz, 1991;Tanaka, 1998), sometimes in the context of other motions (Bradley et al, 1996), but few consider motion in conjunction with depth (but see Frey &Owen, 1999, andPerrone &Stone, 1994), and none have considered the motions ofattended versus unattended objects. Since pedestrian speeds are those to which we adapted, and since these yield quite modest global optical motions, radial expansion patterns are typically not salient except when driving a sports car or landing an airplane.…”

“…Thus, in this analysis, convergence seems the more potent invariant. Frey and Owen (1999) proposed a new measure of the information in a heading display, called the separation ratio. This ratio, (J, can be expressed as:…”

Heading judgments in minimal environments: The value of a heuristic when invariants are rare

“…We coded each heuristic trial in relative terms-as correctly (1) or incorrectly (-I) predicting nominal heading direction according to the relative depth of the two trees, or as being indeterminate (0 for trials with second trees at 90 0 )-and we also calculated the ratio of their depth. Frey and Owen (1999) proposed that the major predictor ofperformance in any given heading display comes from what they called the separation ratio (but to avoid confusion with angular separation, we will call it the depth ratio). This ratio, a, can be expressed as (I) where d N is the distance of the observer to the nearest object in the field of view and d F is the distance to the farthest object.…”