This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
When we open our eyes we instantly -- without any apparent effort -- have a detailed three-dimensional (3D) representation of our environment. However, the subjective ease of vision actually hides a set of very difficult computational problems that our brains are exceptionally good at solving. Foremost among these problems is how the brain deals with the inherent ambiguity in the retinal image. Because vision entails the projection of a 3D world onto a 2D surface, any given image on our retina could be caused by an infinite set of possible 3D configurations in our environment. In this project the investigators attempt to study this type of ambiguity by focusing on the perception of object size. There is an infinite set of object sizes and distances that could give rise to any specific retinal image size. A fundamental challenge to understanding size perception is specifying how distance information -- which is not explicitly represented in the retinal image -- is combined with retinal size information to achieve an accurate and stable representation of object size. The investigators will use functional magnetic resonance imaging (fMRI) and event-related potential (ERP) techniques to understand the role of 3D context in the neural processing of object size. The overarching framework of the research is that distance information is combined with retinal size information in early stages of the visual system. A series of experiments are proposed that focus on how representations of retinal size in early visual cortex are affected by 3D context. Specifically, the experiments will examine the relationship between perceived size and neural activity in early visual cortex, assessing the influence of top-down effects such as attention. The experiments will also examine the timing of 3D contextual effects using time-sensitive ERP measures.
The proposed studies are unique in that they use well-established behavioral and neuroimaging techniques to reevaluate the processing of size, a fundamental object property, in the context of 3D scenes. Understanding how this property is computed will significantly advance our knowledge of how the visual system operates in the 3D world in which we live. In addition, the research project will fit into a larger framework of cognitive neuroscience education and training at the investigator's institution. Specific undergraduate and graduate coursework will incorporate many of the techniques used in this project, which will help students to acquire knowledge of the theory and methodologies underlying state-of-the-art brain imaging research. Finally, the investigator's institution has embarked on a major expansion of facilities and personnel related to cognitive neuroscience and brain imaging research. The proposed project will form a major component of this expansion, the Brain Imaging Innovation Initiative, which is a multifaceted training and research effort aimed at undergraduate, graduate, and post-doctoral students and faculty interested in developing expertise in brain imaging research.
