The fusiform face area: a module in human extrastriate cortex specialized for face perception

Abstract

Using functional magnetic resonance imaging (fMRI), we found an area in the fusiform gyrus in 12 of the 15 subjects tested that was significantly more active when the subjects viewed faces than when they viewed assorted common objects. This face activation was used to define a specific region of interest individually for each subject, within which several new tests of face specificity were run. In each of five subjects tested, the predefined candidate "face area" also responded significantly more strongly to passive viewing of (1) intact than scrambled two-tone faces, (2) full front-view face photos than front-view photos of houses, and (in a different set of five subjects) (3) three-quarter-view face photos (with hair concealed) than photos of human hands; it also responded more strongly during (4) a consecutive matching task performed on three-quarter-view faces versus hands. Our technique of running multiple tests applied to the same region defined functionally within individual subjects provides a solution to two common problems in functional imaging: (1) the requirement to correct for multiple statistical comparisons and (2) the inevitable ambiguity in the interpretation of any study in which only two or three conditions are compared. Our data allow us to reject alternative accounts of the function of the fusiform face area (area "FF") that appeal to visual attention, subordinate-level classification, or general processing of any animate or human forms, demonstrating that this region is selectively involved in the perception of faces.

Fig. 3.

Results of Part II. Left column, Sample stimuli used for the faces versus objects comparison as well as the two subsequent tests. Center column, Areas that produced significantly greater activation for faces than control stimuli for subject S1. a, The faces versus objects comparison was used to define a single ROI (shown in green outline for S1), separately for each subject. The time courses in the right column were produced by (1) averaging the percentage signal change across all voxels in a given subject’s ROI (using the original unsmoothed data), and then (2) averaging these ROI-averages across the five subjects. F andO in a indicate face and object epochs;I and S in b indicate intact and scrambled face epochs; and F andH in c indicate face and hand epochs.

Fig. 1.

Results from subject S1 on Part I. Theright hemisphere appears on the left for these and all brain images in this paper (except the resliced images labeled “Axial” in Fig. 2). The brain images at theleft show in color the voxels that produced a significantly higher MR signal intensity (based on smoothed data) during the epochs containing faces than during those containing objects (1a) and vice versa (1b) for 1 of the 12 slices scanned. These significance images (see color key at right for this and all figures in this paper) are overlaid on a T1-weighted anatomical image of the same slice. Most of the other 11 slices showed no voxels that reached significance at the p < 10⁻³ level or better in either direction of the comparison. In each image, an ROI is shown outlined in green, and the time course of raw percentage signal change over the 5 min 20 sec scan (based on unsmoothed data and averaged across the voxels in this ROI) is shown at the right. Epochs in which faces were presented are indicated by the vertical gray bars marked with anF; gray bars with an Oindicate epochs during which assorted objects were presented;white bars indicate fixation epochs.

Fig. 5.

Midsagittal anatomical image from subject S1 showing the typical placing of the 12 slices used in this study. Slices were selected so as to include the entire ventral surface of the occipital and temporal lobes.