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The effects of inversion, contrast reversal and direction of lighting on face identification

Abstract

    The present study examined the relationships between inversion, direction of lighting and contrast reversal using a face identification task. Previous studies have shown that for face identification, inversion and direction of lighting are additive factors, as are inversion and contrast reversal, indicating that separate processes are responsible. Participants were trained on both upright and inverted faces in order to see whether the assumed holistic nature of upright face encoding would produce different results than the part-based encoding of inverted faces. It was found that orientation and direction of lighting were additive for participants who were trained on upright faces, and tested with positive contrast faces. Upright and brow-lit faces were easier for participants to identify than inverted and chin-lit faces. However, in the case of negative contrast test faces, orientation and direction of lighting interacted. Chin-lit faces showed less of an advantage when they were upright than did brow-lit faces. The opposite pattern of interactions occurred when participants were trained on inverted faces. For positive test faces, orientation and direction of lighting interacted. Brow-lit faces were actually identified more accurately when they were inverted, while chin-lit faces showed the more common advantage for upright orientation. The negative contrast test faces showed additivity between orientation and direction of lighting. In fact, no main effect of orientation was evident at all for that condition.

Example test faces

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