Detection and Processing of Information in Three-Dimensional Space

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The long-term aim of my research programme is to understand the fundamental perceptual principles underlying human spatial abilities. Using virtual reality (VR) technology and various real world testing paradigms, we will further pursue the following three lines of research 1) multisensory integration in locomotion and 2) visual control of impending collision; 3) perception of visual events in near peripersonal and extrapersonal space. Our first line of research focuses on how the human brain interprets and integrates visual (optic flow) and body-based (proprioceptive, vestibular) information during locomotion. In order to assess the role of each sensory cue individually and gain a better understanding of how these cues interact with and are integrated with one another to form a single perception, we have used several novel experimental paradigms involving self-motion (such as bicycling and walking) to create cue conflict scenarios. The next goal of this first research program will concentrate on further investigating and quantifying the dynamic interactions that occur between visual and body-based information during self-motion. By modeling the empirical findings using Bayesian model we will be better equipped to quantify how previous sensory experiences affect current sensory processing. This line of research will not only help us understand the mechanisms involved in perception of travelled distance, but also provides insight into the general principles that define how the brain combines multiple sources of information. While our first line of research focus on the multisensory processing of the extent of PAST movement of the observers in the environment, our second line of research concentrate on the visual processing of FUTURE collision before the observers intercept objects in the environment during either object motion (e.g., an oncoming car), and the motion of the visual environment experienced as a result of the observer's self-motion (e.g., walking and driving). Our recent studies provided clear empirical evidence demonstrating that observers use optical variable tau to make judgement of impending collision. In our next grant period we will conduct psychophysical studies exploring the mechanisms of processing for more complicated forms of motion. We will compare human performance under object motion, self-motion, or both. In addition to perception of motion, we will also examine visual motor control in complex, naturalistic forms of motion processing and collision avoidance in simulated driving tasks on our high-end driving simulator (equipped with eye tracking). Our third line of research will follow up our recent exciting discoveries of differential processing of visual targets presented at near (peripersonal) and far (extrapersonal) viewing distances, even though visual stimuli in near and far viewing conditions were matched for visual angle and luminance. We will continue to examine the underlying mechanisms for such a viewing distance effect. Our pilot data so far suggest that near and far visual spaces might be differentially processed by dorsal and ventral visual streams respectively. The setups in our VR laboratory afford great experimental control over three-dimensional, multisensory, dynamic, ecologically valid, stimulus presentations. This research program has not only allowed me to explore fundamental perceptual principles underlying visuomotor control, but it can also be employed in the design of better standardized tests and training/rehabilitation for drivers/pilots and the design of car, road sign and driving/flight simulators.