Dissociating retina- and face-centered reference frames of human face recognition

Face identity recognition is a core function of the human brain, predominantly driven by horizontally oriented facial cues. While face processing largely operates in a face-centered reference frame, it is not devoid of retinotopic sensitivity. Addressing whether face rotation influences the orientation tuning profile of identity recognition enables a direct empirical test of the reference frame of human face identification. Forty-two young adults performed identity recognition of famous faces filtered to restrict content to narrow orientation bands (i.e., from 0° to 150°, in 30°-steps), and presented either upright, rotated by ±45°, or by ±90° away from upright. If the horizontal face identity information is defined along face-centered coordinates, identity recognition performance should stay tuned to the horizontal irrespective of rotation angle. Any contribution of the retina-centered reference frame should cause the peak of orientation tuning to shift away from the horizontal, in the same direction as the stimulus rotation. While overall identity recognition performance decreased when faces were rotated by ±90° compared to upright and ±45° rotation, it kept broadly tuned to the horizontal range of the face stimulus regardless of rotation angle. However, the advantage of the horizontal over the vertical range decreased significantly for ±90° compared to upright and ±45° rotations. Through the systematic investigation of the orientation tuning parameters across stimulus rotation, the present work provides quantitative evidence that the visual information driving human face-specialized identity recognition is defined within the reference frame of the face-image.