Stimulus and context effects on perception

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One of the main goals of the visual system is to recognize objects so that we may interact with them appropriately. Although recognition of people, places, and things typically appears effortless and instantaneous, perception takes measurable time, and the visual system must overcome tremendous obstacles for recognition to occur. For example, various elements of the raw images that reach our eyes must be organized appropriately, so that we perceive coherent, meaningful, complete objects rather than inappropriately segmented, confusing scenes. Given the complexity of the recognition process, it is not surprising that we have relatively little understanding of the neural mechanisms underlying recognition. The objective of the current proposal is to advance that understanding, particularly with respect to the role of stimulus and contextual information on the visual perception of faces. Over the past decade, my lab has refined a number of psychophysical and electrophysiological techniques that enable us to address these issues at different levels than previously possible. The current proposal extends this work, especially with respect to understanding the neural mechanisms underlying face recognition, and branches into new areas examining how aspects of visual perception are altered by contextual cues and experience. Although my work relies on behavioural techniques to make inferences about underlying neural processes, I also make use of converging methodologies -- combining modern psychophysical approaches with neuroimaging techniques, such as electroencephalography. My behavioural research will utilize psychophysical discrimination tasks to identify the precise aspect of a stimulus observers use in recognizing and discriminating faces. I also will how these behavioural measures correlate with neural activity, including the N170 and N250 (two key markers of face perception within the ERP), but also broader elements of the EEG signal using a range of statistical approaches we have refined to understand brain-behaviour interactions at the level of the individual observer and the individual trial. The results of these studies will provide insight into how the brain processes information about faces and other objects; will determine which aspects of behaviour and neural processing are stable, and which are malleable, based on learning and context; and will enhance our understanding of how sensory information is combined across modalities. Although the research program focuses on fundamental scientific issues, results may provide insights for the development of artificial vision systems, and neurotechnologies to enhance face perception. The research program also will provide excellent training for numerous trainees, equipping them with the scientific knowledge and professional, research, and communication skills to succeed in their future careers as researchers.