Visual perception of motion in the 3D environment

Tasks related to motion perception are some of the most frequent and important for surviving in a world filled with motion. Animals face tremendous evolutionary pressure to develop accurate systems for estimating the velocity of moving objects and predicting future trajectories. Motion detection and estimation were crucial for survival because they enabled animals to avoid being caught by predators and for predators to capture prey. Today, the visual system enables us to interact with the dynamic modern world we live in. Due to its clear evolutionary significance the study of motion has been common in vision science. Many prior studies have focused on two-dimensional (2D) motion perception and depth perception separately. Fewer studies have explicitly studied three-dimensional (3D) motion perception. This dissertation situates itself within a recent trend that focuses on the study of 3D motion by using a unified framework considering both motion and depth. I present two major projects that advance the study of 3D motion perception. First, I introduce novel stimuli that isolate the primary binocular cues to 3D motion. These novel stimuli allow for the characterization of two separate mechanisms that underlie the perception of motion-through-depth. I present two psychophysics experiments that use these stimuli to characterize the spatiotemporal properties of these mechanisms. In the second project, I extend the powerful continuous tracking paradigm to virtual reality (VR) to study the relative contribution of binocular and monocular cues to 3D motion. This chapter highlights the limitations of disparity processing and the contribution of monocular depth cues for a 3D motion tracking task. The work in this dissertation falls at a midpoint on the spectrum between traditional approaches to psychophysics and more recent developments using naturalistic stimuli and tasks. Taken together, the results described here advance what we know about binocular and monocular mechanisms for the perception of motion-through-depth. This work forms a foundation for testing how the primate visual system makes use of a variety of depth and motion cues to encode 3D motion. Future studies may further explore how coordination between the motion and motor systems enable us to interact with a dynamic 3D world