EASTBIO Investigating a tripartite model of human 3D spatial vision through psychophysics and neuroimaging

A significant challenge for current models of human space perception and 3D vision has been in explaining the underlying encodings supporting our subjective awareness of visual space. When we look out into the world before us, we perceive what appears to be a singular coherent representation of the physical 3D world. However, a wide range of phenomenological, behavioural and neurophysiological findings in humans suggest strongly that this this is not the case. Integrating phenomenological observations, behavioural empirical data, evolutionary logic and neurophysiological evidence leads to the conjecture that human conscious awareness of visual space is underwritten by multiple, sometimes mutually inconsistent, spatial encodings. The assessment of the primary competencies in the human awareness of space has led to a recent conjecture of three major types of spatial encodings. The most primitive of these spatial encodings is proposed to support the competency of the awareness of distance at an ambulatory scale (operationally defined as egocentric distance) which helps to guide actions such as navigation, as well as a primitive awareness of ordering of objects in depth. This encoding is hypothesised to involve temporal paleocortex regions. The second spatial encoding is proposed to support the awareness of object layout and 3D shape without scale (operationally, relative depth). This is the encoding that allows us to perceive depth and 3D dimensionality in both real and pictured scenes (like photographs). This encoding is proposed to be instantiated in the ventral visual stream of the neocortex. The third spatial encoding is proposed to support the competency of fine-grained awareness of intra- and inter-object spatial separation in near space (operationally, scaled (absolute) depth). This is the representation that allows us to interact with objects in near space, e.g., to pick up an object and manipulate it. This representation is proposed to be instantiated in the dorsal visual stream. The tripartite proposal helps understand many empirical observations, as well as some peculiar but ubiquitous aspects of human awareness of space and 3-dimentionality, such as why we can perceive depth in pictures, and why 3D movies give us a special sensation of awareness of 3-dimentionality that is different from that obtained in a normal 2D movie. This project will combine human psychophysics approaches along with human neuroimaging methods (EEG, fMRI) to investigate the existence of a tripartite encoding structure underlying human 3D vision.