Dynamic Perspective: effects on Humans’ Depth Perception and on Neural Activity in monkey’s V1

Ma’ayan Gadot 1, Gregory C. Deangelis 2 and Hamutal Slovin 1
1. The Leslie and Gonda (Goldsmied) Multidisciplinary Brain Research Center, Bar-Ilan University, Israel
2. Brain and Cognitive Sciences, University of Rochester, New York, USA

Comprehending the 3-D structure of our environment is a pivotal ability that influence many imperative behaviors, thus perceiving depth is essential to daily operation. Many brain regions and visual cortical circuits participate in sensing depth by relying on different depth cues. Some depth perception cues require binocularly vision (two eyes), while others can have ample information reaching from only one eye (monocular cues).

            One principal monocular cue is motion parallax (MP), which is based on the proportional changes in objects' motion velocity while one moves through the physical world. Previous psychophysical studies demonstrated that humans can disambiguate depth sign (near vs. far) from MP cues. In addition, it has been suggested that simulating the global visual changes of eye rotation over time during observer’s translation in space (namely, dynamic perspective, DP) can also produce an effective cue that elicits strong depth perception, while in the absence of the perspective cue (namely, retinal motion, RM) depth sign is ambivalent. Despite the accumulating progress in this field, the effects of DP parameters on depth perception were barely studied.   Finally, neurophysiological findings from monkeys demonstrated the selectivity of neurons in extra-striate cortex to MP and DP cues. However, the neuronal mechanisms of the primary visual cortex involved in depth perception are not well understood.

            In the current study we investigated the ability of humans to dis-ambiguous depth-sign from DP cues as well as their reaction time. Stimuli comprised of DP provided sufficient information to disambiguate the depth-sign and the observers’ psychometric curve strongly correlated with the stimuli depth saliency. In contrast, discrimination of targets lacking the perspective component was only weakly correlated with the simulated depth. More so, we manipulated the stimuli motion coherence and stimuli duration to evaluate their effects on the ability to perceive depth-sign. Finally, we present preliminary neuronal response in V1 obtained by voltage sensitive dyes imaging (VSDI) from NHP engaging in a passive DP task.