Despite the fact that visual scenes may contain multiple objects and people, humans can recognize the objects and individuals with ease and accuracy. Research in my lab focuses on studying how this is achieved - what are the necessary psychological processes and representations that underlie abilities such as object segmentation and recognition, face recognition, mental imagery, reading and writing and spatial attention? Although these questions are asked within the framework of information-processing models used in cognitive psychology, I am also interested in identifying the neural mechanisms which are responsible for these complex abilities.
The major approach I use to address these questions is to study the behavior of human adults who have sustained brain damage (usually through stroke or head injury) which selectively affects their ability to carry out these processes. For example, some patients are impaired at recognizing faces (prosopagnosia or face blindness), some are impaired at recognizing objects (visual object agnosia) and some are unable to represent visuospatial information (hemispatial neglect). By examining patterns of associations and dissociations among abilities after brain damage, one can make inferences about the functional and structural organization of the brain. This neuropsychological approach is combined with several other methods: experiments from traditional cognitive psychology paradigms (analyzing the response latencies and accuracies of normal subjects); simulations of artificial neural networks which may be used to model these processes and their breakdown following brain-damage; and functional neuroimaging studies which examine the biological substrate of high-level vision.
A final thread to my research is to conduct rehabilitation studies with the brain damaged subjects in order to treat the observed deficit. Carefully planned rehabilitation studies provide valuable information which can shed light on the mechanisms underlying visual cognition.