Visual psychophysics of human face processing

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DESCRIPTION (provided by the applicant): It has been assumed in the study of vision that there are distinct sub-systems or modules. In the field of visual object recognition this is most clearly evident in the question--Are faces special? This can be divided into two research questions. (1) Does the processing of faces operate according to the same or different computational principles as the processing of other objects? (2) are there a separate anatomical regions in the visual system for the processing of facial images, distinct from the processing of visual objects? To address these fundamental issues, we turn to visual psychophysics which has proven itself, both as a method to isolate functional subsystems and as a way to link such systems to underlying neural substrates. We rely on two new procedures to evaluate holistic processing: spatial summation and categorical perception (CP) noise. We will use psychophysical procedures to investigate the range and scope of holistic processing in the recognition personal identity and facial emotion. We will examine holistic processing under a range of stimulus conditions to better determine its characteristics, this includes varying spatial frequency and fragmenting the facial image. We will also determine whether holistic processing is present in highly practiced subordinate recognition tasks. We will also delineate the functional anatomy of face processing using fMRI and relying on variants of the face inversion effect to more clearly identify those parts of the brain that are participating in face-specific processes. We ask whether these areas will coincide with putative face and object areas. We will also use event related fMRI to see the co-localization of detection and recognition specific processes with face and object areas. We will also study face detection, developing a measure of holistic processing, thus enabling a comparison of holistic processing in both recognition and detection. WE will look for a dissociation of face detection and recognition processes in prosopagnosic patients and evidence for a subcortical component of face detection in blindsight patients.