Multidimensional internal dynamics underlying the perception of motion

Abstract

When ambiguous visual stimuli are presented continuously, they often lead to oscillations between usually two perceptions. Because of these oscillations, it has been thought that the underlying neural dynamics also arises from a binary or two-state system. Contradicting the binary assumption, it has been shown recently that the perception of some ambiguous stimuli is governed by continuously varying internal states, measured as biases that differ considerably from one observer to the next and that can also evolve over time (Wexler et al., 2015). Here I study bias patterns in the motion quartet, an ambiguous apparent motion stimulus, as the quartet's orientation is varied. The bias patterns are robustly idiosyncratic, and are even more complex than those that have been described previously. There are two qualitatively different bias types: some observers prefer a translation axis, while others show preference for a rotation direction. Each type also varies parametrically: the orientation of the preferred axis, and the direction of preferred rotation. The are also clear cases of combination of the two bias types. When measured repeatedly over 9 hours, the bias patterns usually remain stable, but also sometimes evolve both parametrically (e.g., change of preferred axis), as well as across bias type (change from axial to rotational bias). Control experiments revealed that the variety of bias patterns observed across subjects, and their changes over time, are not due to voluntary decisions. Overall, these results exhibit the multidimensional complexity of internal states underlying the perception of even simple stimuli.

Idiosyncratic preferences in transparent motion and binocular rivalry are dissociable

“…These findings indicate that idiosyncratic preferences in a visual feature (motion direction) can be dissociated at different stages of visual information processing. The weak directional preferences in binocular rivalry are in stark contrast to findings from other types of ambiguous stimuli ( Schütz, 2014 ; Wexler, Duyck, & Mamassian, 2015 ; Wexler, 2018 ), suggesting that motion direction plays a less important role in binocular rivalry.…”

Spatial Heterogeneity in Bistable Figure-Ground Perception

“…Our findings thus parallel the spatial heterogeneity reported for perceiving stimulus size ( Afraz et al., 2010 ; Moutsiana et al., 2016 ; Schwarzkopf & Rees, 2013 ); location ( Kosovicheva & Whitney, 2017 ); orientation, shape, and complex features like the apparent identity, age, or gender of faces ( Afraz et al., 2010 ; Visconti di Oleggio Castello et al., 2018 ); and ambiguous motion ( Wexler et al., 2015 ). The findings are also reminiscent of heterogeneity in the perception of bistable motion stimuli depending on their orientation ( Wexler, 2018 ).…”

“…Stimuli appear smaller in peripheral compared with central vision ( Anstis, 1998 ; Bedell & Johnson, 1984 ; Helmholtz, 1924 ; Moutsiana et al., 2016 ; Newsome, 1972 ). Even basic visual features, such as object position, size, and shape, appear differently across the visual field and viewing conditions or when measured at different times ( Afraz et al., 2010 ; Wexler, 2018 ; Wexler et al., 2015 ). Further studies confirmed such biases for the apparent size ( Moutsiana et al., 2016 ; Schwarzkopf & Rees, 2013 ) and position ( Kosovicheva & Whitney, 2017 ) of visual stimuli.…”