The interaction between orientation and motion signals in moving oriented Glass patterns

Abstract

Previous psychophysical evidence suggests that motion and orientation processing systems interact asymmetrically in the human visual system, with orientation information having a stronger influence on the perceived motion direction than vice-versa. To investigate the mechanisms underlying this motion-form interaction we used moving and oriented Glass patterns (GPs), which consist of randomly distributed dot pairs (dipoles) that induce the percept of an oriented texture. In Experiment 1 we varied the angle between dipole orientation and motion direction (conflict angle). In separate sessions participants either judged the orientation or motion direction of the GP. In addition, the spatiotemporal characteristics of dipole motion were manipulated as a way to limit (Experiment 1) or favour (Experiment 2) the availability of orientation signals from motion (motion streaks). The results of Experiment 1 showed that apparent GP motion direction is attracted towards dipole orientation, and apparent GP orientation is repulsed from GP motion. The results of Experiment 2 showed stronger repulsion effects when judging the GP orientation, but stronger motion streaks from the GP motion can dominate over the signals provided by conflicting dipole orientation. These results are consistent with the proposal that two separate mechanisms contribute to our perception of stimuli which contain conflicting orientation and motion information: (i) perceived GP motion is mediated by spatial motion-direction sensors, in which signals from motion sensors are combined with excitatory input from orientationtuned sensors tuned to orientations parallel to the axis of GP motion, (ii) perceived GP orientation is mediated by orientation-tuned sensors which mutually inhibit each other. The two mechanisms are revealed by the different effects of conflict angle and dipole lifetime on perceived orientation and motion direction.

Spatial and Temporal Selectivity of Translational Glass Patterns Assessed With the Tilt After-Effect

“…The authors did not find a significant difference in detection thresholds when stimuli were composed of more than two unique GP frames and were presented between 20 and 60 Hz. Similarly, in our study, we found stronger TAE magnitude when the adapting GP temporal frequency was between 10.59 and 42.37 Hz, suggesting that there might be a specific range of temporal frequencies for optimal temporal summation, which is a process in which the neurons combine both the temporal and spatial information of a stimulus ( Day & Palomares, 2014 ; Nankoo et al., 2012 ; Pavan, Ghin, et al, 2017 ). Importantly, our results also showed that increasing the adapting temporal frequency up to 84.75 Hz, the TAE magnitude was not different from the static adapting condition.…”

“…In dynamic GPs, the rapid succession of frames induces the perception of apparent motion along the orientation axis of the pattern even though there is no dipole-to-dipole correspondence between successive frames. Therefore, no coherent motion is present in this class of stimuli ( Nankoo et al., 2012 ; Pavan, Bimson, et al., 2017 ; Ross, 2004 ; Ross et al., 2000 ).…”

“…Given that the refresh rate of the screen was constant at 85 Hz, longer frame durations were obtained using multiples of a single frame duration (i.e., $0.0118 s). in this class of stimuli (Nankoo et al, 2012;Pavan, Bimson, et al, 2017;Ross, 2004;Ross et al, 2000). The test pattern (Figure 1B) was a sinewave grating with a spatial frequency of 5.56 c/deg, corresponding to the inverse of the dipoles' spatial constant (i.e., the interdot distance-see Figure 5 for more details).…”

Towards a unified perspective of object shape and motion processing in human dorsal cortex

“…However, in the case of rotational motion, the opposite is true: large object appear to rotate faster than small ones and moreover the degree to which size influences perceived rotational speed is itself mediated by the shape of the object (Blair, Goold, Killebrew & Caplovitz, 2014). The perceived speed of an object can also be influenced by its orientation relative to the direction of motion with objects elongated in the direction of motion appearing to move faster than ones moving in a perpendicular direction (Krolik, 1934; McCarthy, Cordeiro, & Caplovitz, 2012; Metzger, 1936; Or, Khuu, & Hayes, 2010; Pavan, Bimson, Gall, Ghin, & Mather, 2017; Porter, Caplovitz, Kohler, Ackerman, & Peter, 2011; Series, Georges, Frégnac, & Lorenceau, 2002). In all of these examples, the shape of the object has effects on its perceived velocity, which in turn may affect how an observer interacts with it (Medendorp, de Brouwer, & Smeets, 2018).…”

Mechanisms Underlying Directional Motion Processing and Form-Motion Integration Assessed with Visual Perceptual Learning

“…According to Ungerleider and Mishkin [1], these two visual streams were physically segregated yet functionally independent. However, several later research studies disputed this perspective, advocating an integrated view of the visual brain [2][3][4][5][6][7][8][9]. Dynamic Glass patterns (GPs) [10] and random dot kinematograms (RDKs) are two types of visual stimuli commonly employed to assess the functional properties of the dorsal and ventral streams.…”