Shaun P. Vecera - US grants

This project will investigate a fundamental aspect of human perception, the ability to organize the visual world into figures and backgrounds. In everyday visual scenes, objects overlap and occlude one another, which necessitates a visual process for determining which objects lie in the foreground (figures) and which lie in the background. Psychologists have proposed a set of rules that describe figure-ground segregation. For example, a symmetrical region is more likely to be perceived as a figure than as the background. However, this descriptive approach does not specify the mechanisms of figure-ground segregation-the precise computations that allow these rules to be instantiated. Neurophysiological studies in nonhuman primates, in contrast, show promise for elucidating the mechanisms of figure-ground segregation, but the results of these studies are difficult to link with studies of human perception. The goal of this project is to bridge the gap between human perception and monkey neuro-physiology in figure-ground segregation by using noninvasive electro-physiological recordings of the brain's activity (colloquially known as 'brain waves' and technically as 'event-related potentials'). These recordings will allow us to assess the time course and neuroanatomical substrates of figure-ground segregation, thereby elucidating both the cognitive and neural mechanisms of figure-ground segregation. We hypothesize that figure-ground segregation relies on a mechanism that amplifies the neural representation of a figure relative to the neural representation of the ground. Our research uses non-invasive electro-physiological methods that can test this hypothesis more directly by measuring the sensory processes associated with both "figures" and "grounds." This research will provide an understanding of how the brain processes complex visual scenes, which may have implications for artificial vision systems and techniques for rehabilitation of visual perception following brain injury.

Our visual worlds are filled with multiple objects. However, because the visual system has a limited processing capacity, we do not process all of the objects. We have objected-based attentional mechanisms that restrict our processing to a subset of visual objects. Research on object-based has investigated only how humans attend to entire projects. But, objects are composed of parts, a point neglected by studies of object-based attention. Can attention select the individual parts of objects? My previous research has addressed this question, and in the present proposal I outline a series of experiments aimed at understanding the relationship between part- based attentional processes and object recognition processes. Recent object recognition theories propose that there are at least two recognition processes, one in which objects are decomposed into parts and instead are recognized as complex wholes. To determine if part-based attention arises from object recognition processes or is separate from recognition, I will study the effects of part-based attention on objects that are recognized with the non-decomposition process. Thus, if part-based attention arises from the part-decomposition recognition system, then faces should not show part-based effects. In contrast, if part-based attention is separate from recognition processes, then part attention may allow a face to be decomposed into its parts, even though faces do not decomposed for recognition processes, I will conduct control experiments to determine (1) if part-based effects hold for other complex objects (e.g., houses) and (2) if face recognition indeed does not require decomposition. Finally, experiments investigating part attention to upside down faces and the effect of part-based attention on encoding faces into memory will allow me to elucidate further the relationship between attentional processes and object recognition processes. The proposed research is relevant for several mental health issues. For example, different neurological disorders afflict attentional processing (i.e., neglect) and object recognition (i.e., agnosia). Integrating the object attention and object recognition literatures could provide an understanding of the relationships between the neural regions damaged in these syndromes, information which may be useful for rehabilitation.

Human vision is exceptionally flexible. Consider searching for a familiar face in a crowd, finding car keys in a cluttered kitchen, chasing down an opponent in football, or threading through a crowded restaurant to find a table. How does vision accommodate such a variety of visual environments and achieve such diverse goals? One key is selective attention, which allows a person to focus on relevant aspects of the visual environment. But how does the mind determine what is relevant? What is the nature of control of visual attention?
With support from the National Science Foundation, Dr. Shaun Vecera and Dr. Michael Mozer propose research to investigate selective attention. Dr. Vecera will conduct experimental studies that explore human behavior in novel tasks and unfamiliar environments to investigate how people exploit visual cues in the environment to enhance performance. Dr. Mozer will build computer simulation models to explain the experimental results. Broader impacts of this research include building artificial systems with the flexibility of human vision and improving the design of user interfaces for computer systems and mechanical or electronic devices. Additionally the proposed research may inform the diagnosis of control deficits due to brain damage. A computer model of human control can be damaged in various ways, to simulate brain damage, leading to a better understanding of the consequences and strategies for remediation.

Finding the ketchup in the refrigerator is an everyday activity that requires the use of visual attention. When faced with a cluttered visual environment (the refrigerator), the human visual system can isolate a single, behaviorally relevant item (the ketchup). Visual attention reduces the complexity of the visual world, enabling us to successfully navigate and function without being overwhelmed with the sheer amount of visual information. But how does attention know what to select? Some theoretical accounts propose that attention is directed toward salient (conspicuous) objects, whereas other accounts state that attention is directed toward goal-relevant objects. One limitation of both of these accounts is that they fail to acknowledge that attention is typically used in conjunction with action, which involves coordinating your body with objects in the environment. The goal of this research project is to understand how the body and its position (such as an outstretched arm reaching into the refrigerator) controls visual attention. The research team will investigate this notion of 'embodied attention' using both behavioral and brain imaging (event-related potential) methods.

Research on embodied attention is important in providing a fuller account of how the mind and body interact to function successfully in the world. The research also offers the possibility to improve the lives of older adults and those with neuropsychological deficits, because these people often have impairments in both motor function and the use of attention. It may be that understanding the connection between body position and attention will lead to treatments that increase the ability of these target populations to function in the world.