PROJECT SUMMARY Our understanding of human vision is based almost exclusively on studies of experimental proxies for reality– typically artificial two-dimensional (2D) pictures. Studying responses to artificial stimuli neglects the fact that humans have evolved and developed in the real world (RW), and that our behavior and brain processes are likely to reflect the important features of tangible objects and environments, including depth, tangibility, actability, and multisensory processing. Yet little is known about how real objects are processed and represented in the brain, and how such responses compare to artificial stimuli. The long-term goal of this research is to elucidate the mechanisms that are engaged during naturalistic vision. The objective of this application is to understand how, and why RW stimuli, compared with proxies, influence behavior and brain responses. The central hypothesis is that response patterns to RW stimuli will be qualitatively different than 2D/3D pictures; these differences will unfold during development, and they will be causally linked with computations in dorsal cortex. These format-related differences will manifest during perception because the statistics of naturalistic contexts are likely to be captured during experience, and because real objects (but not artificial stimuli) are relevant for spatial and multisensory processing, and for action. The rationale for the research is that studying richer stimuli, like those encountered in everyday life, will fundamentally improve our understanding of human brain function, and expand the generalizability and translational value of scientific knowledge to RW settings. The central hypothesis will be tested via three specific aims: (1) Determine how real stimuli modulate behavioral and neural response patterns in adults, (2) Determine how real stimuli modulate neural response patterns during development, and (3) Isolate the causal contribution of dorsal cortex to real object effects. The aims will be examined using behavioral and fMRI studies with adults, and fMRI studies with children and neuropsychological patients with perceptual deficits. The studies employ novel and innovative stimuli, devices, and procedures, designed for presenting large numbers of real objects in rapid succession in the laboratory and the fMRI scanner, under controlled viewing conditions. The contribution of the research is that it will elucidate the psychological and neural systems that are engaged during naturalistic vision. This contribution is significant because it will reveal how the integrated workings of the perception-action systems shapes visual cognition, why these systems should be studied with RW stimuli, and how their activity influences and improves performance.