Shape, Object, and Scene Perception.

We have proposed a theory of real-time human object recognition that posits that objects and scenes are represented as an arrangement of simple, viewpoint-invariant volumetric primitives, such as bricks, cylinders, wedges, and cones, termed geons. Geon theory has been implemented as a neural network (Hummel & Biederman, 1992) and has undergone extensive assessment in psychophysical experiments (see Biederman, 1995, for an overview). Current projects in the lab are investigating the effects of contrast polarity on the detection of non-accidental properties and the role of spatial relations in scene perception.

Face Recognition.

This project explores the extent to which the similarity of faces, when they can't be distinguished by easy features, can be modeled in terms of the pattern of activation over a lattice of spatial filters (Biederman & Kalocsai, 1997). Whereas viewpoint invariant properties and an explicit arrangement of distinctive parts appears to suffice for object recognition, a similarity space that preserves the metrics implicit in the original spatial filter activations may suffice for face recognition. Current projects in the lab are exploring the information used in making different judgments about faces, what surface properties of faces make them different from objects, and how psychophysical effects such as the 'other race effect' arise from a consideration of these properties.

The Neuroscience of Object Recognition

We have two collaborative research projects in which we are investigating the tuning of neurons in IT of the macaque to variations in object shape. In collaboration with Dr. Rufin Vogels of the Katholieke Universiteit of Leuven, Belgium, we have been found that there is stronger tuning to variations to differences in geons than metric properties (such as aspect ratio) (Vogels, Biederman, Bar, & Lorincz, 2001). In collaboration with Prof. Benedek Gysrgy and Dr. Gyula Kovács of the Department of Physiology at the Albert Szent-Gysrgyi University in Szeged, Hungary, we have been studying the response of IT neurons to differences in the surface appearance of objects as well as the differential response of these cells to contour-deleted line drawings. What brain areas are active during object recognition? We are investigating this question through fMRI and patient studies (Biederman, Gerhardstein, Cooper, & Nelson, 1997). We are currently conducting an extensive investigation of a very high functioning prosopagnosic individual.

A Theory of Perceptual and Cognitive Pleasure.

Our selection of which movie to see or book to read, whether to stay in a conversation at a party or freshen our drink, and where to look with our next fixation is decidedly non random. What controls this selection when an individual is not hungry, avoiding harm, sexually interested, etc., or engaged in deliberate search? And how can this expression of interest be manifested in real time, at the rate of three visual fixations per second? The surprising discovery of a gradient of opiate receptors in cortical areas associated with perception and cognition may provide the key for understanding the spontaneous selectivity of perception and thought. This system serves to maximize the rate at which we acquire new but interpretable information. In our lab, we are currently using behavioral, neuroimaging, and pharmacological methods to investigate the role of the ventral visual stream in affective attentional selection.