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.
