Abstract
Detection of faces in visual scenes has received extensive attention in machine vision, but limited research has addressed face detection in humans. Here we assess face detection in six participants with acquired prosopagnosia resulting from a variety of lesions to better understand the processes and neural areas contributing to face detection and the relation of detection to other stages of face recognition. All six participants showed severe impairments on tests of facial identity recognition, confirming prosopagnosia, and participants were also extensively tested for perceptual discrimination of faces. We used structural MRI to delineate the lesions and functional MRI to show the status of the core regions of the face-processing network (OFA, FFA, STS). Two tasks requiring visual search for the presence of a face among distractor stimuli assessed detection in the patients and 12 age-matched controls. Two participants, R-AT2 and B-AT1, performed normally on both tasks. These patients had anterior temporal lesions that did not affect their core face-processing network. Two participants, R-AT1 and R-IOT4, had severe detection impairments while the performance of R-IOT1 and B-AT/IOT1 was borderline. These four subjects all showed difficulty on perceptual tasks requiring discrimination of facial identity. Except for R-AT1, all subjects had lesions to right inferior occipitotemporal cortex, with loss of the FFA and OFA in R-IOT1 and B-AT/IOT1 and loss of the FFA alone in R-IOT4. Furthermore, DTI analysis in R-AT1 suggested reduced fractional anisotropy in the region of the FFA and OFA. The association between detection and identity perception suggests that these abilities may be supported by the same processes. Impairment in these abilities correlates with damage to the core face-processing network in the right hemisphere. Face detection deficits in R-IOT4 despite preservation of the right and left OFA indicates that these regions are not sufficient on their own to support detection.
Support from ESRC (RES-061-23-0040) to BD and CIHR (MOP-77615) to JB.