The faces were created using FACES™ 4.0 by IQBiometrix Inc and
eye-removal was done in Adobe™ Photoshop CS5. Forty different face
identities were created (20 males, 20 females) by choosing a combination
of different internal features displayed at the exact same location
within the same bald face outline. This ensured features remained in
constant relative positions in every face. This also ensured that the overall
luminance across pictures was identical within a category, with only
tiny local variations seen as a result of using different features
(e.g. a larger mouth, smaller eyes, thinner eye brows etc.). A simple
180° rotation created the inverted stimuli and all images were presented
over a white background. Stimuli subtended 9.5° horizontally and
13.6° vertically of visual angles. Angular distances between fixation
locations were as follows: forehead-nasion: 2.1°; nasion-nose tip:
2.1°; nose tip-mouth: 2.1°; nasion-left/right eye: 1.9°. The positioning
of the face to obtain the desired feature fixated resulted in opposite
face positions for upright and inverted faces for two fixation locations.
When upright, faces were situated almost entirely in the upper visual
field when fixation was on the mouth and almost entirely in the
lower visual field when fixation was on the forehead. The opposite
pattern was seen when faces were inverted (Fig. 1).