The shape of motion perception: Global pooling of transformational apparent motion

Abstract

Transformational apparent motion (TAM) is a visual phenomenon highlighting the utility of form information in motion processing. In TAM, smooth apparent motion is perceived when shapes in certain spatiotemporal arrangements change. It has been argued that TAM relies on a separate high-level form-motion system. Few studies have, however, systematically examined how TAM relates to conventional low-level motion-energy systems. To this end, we report a series of experiments showing that, like conventional motion stimuli, multiple TAM signals can combine into a global motion percept. We show that, contrary to previous claims, TAM does not require selective attention, and instead, multiple TAM signals can be simultaneously combined with coherence thresholds reflecting integration across the entire stimulus area. This system is relatively weak, less tolerant to noise, and easily overridden when motion energy cues are sufficiently strong. We conclude that TAM arises from high-level form-motion information that enters the motion system by, at least, the stage of global motion pooling.

Role of form information in motion pooling and segmentation

“…This hypothesis follows from the fact that many experimental manipulations that change the percept of occludedaperture stimuli also similarly affect the perception of motion transparency for conventional motion stimuli (Lorenceau & Alais, 2001;Takeuchi, 1998). However, direct comparison with studies using conventional motion stimuli is difficult because of differences in stimulus strength and spatial frequency, which greatly affect integration (Amano, Edwards, Badcock, & Nishida, 2009b;Dickinson, Broderick, & Badcock, 2009;Heeger, Simoncelli, & Movshon, 1996;Tang et al, 2013). Our stimulus allows us to overcome this limitation because the same motion information can be maintained while eliminating the second-order form information.…”

“…clear sense of either transparency of integration and, therefore, allowed us to control low-level factors that influence motion sensitivity by using the same number of Gabor over the same area as the occluded-aperture stimuli Tang et al, 2013).…”

“…Presenting a series of locally-uncorrelated patterns, but with a globally-consistent pattern, results in the perception of motion in the global pattern direction, likely through activation of the motion streak mechanism Burr & Ross, 2002;Ross et al, 2000). Adding explicit hard edges to Gabors pulls the perceived direction of motion toward the orientation cue (Badcock, McKendrick, & Ma-Wyatt, 2003;Edwards, Cassanello, Badcock, & Nishida, 2013), and form changes, without a corresponding motion energy signal, can be pooled into a global motion percept (Tang, Dickinson, Visser, Edwards, & Badcock, 2013;Tse, 2006). Taken together these studies suggest that form information enters the motion system by, at least, the stage of global motion integration and that this information can assist in the recovery of object motion direction.…”

Stimulus dependencies of an illusory motion: Investigations of the Motion Bridging Effect

“…When groups of these dot pairs are presented and switched simultaneously, the perceived direction of the oscillation is identical in all the pairs. In addition, other investigations have shown that when multiple line-motion stimuli are presented together, their motion signals can pool and be integrated to form a joint global motion percept (Tang, Dickinson, Visser, Edwards, & Badcock, 2013;Tse & Logothetis, 2002). These yoking and integration effects could result in all the inducing ring segments contracting in the same direction to generate the rotation percept.…”

Catching the voltage gradient—asymmetric boost of cortical spread generates motion signals across visual cortex: a brief review with special thanks to Amiram Grinvald

“…[66][67][68][69][70] Thus, motion streaks may be analyzed unconsciously and separately over time [71][72][73][74] to contribute to further analysis such as form-from-motion at higher processing stages. 20,21,62,69,70,[75][76][77][78][79][80] Interactions mediated by propagating waves of cortical population activity across V1 have been demonstrated for a variety of mammalian species (for example, see Refs. 20 and 81-91).…”