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Abstract:
Can stimuli rendered invisible through lateral masking
(crowding) or through adaptation (Troxler fading) contribute to the
perception of emotion and/or apparent motion? EXPT 1) A cartoon
face (smiling or frowning) was surrounded on four sides by four
neutral faces. With eccentric viewing, ten subjects were asked to
discriminate mouth curvature (convex vs. concave) when the central
face was pointing sideways or was upside-down vs. expression when
it was upright. Discrimination of convexity/concavity for the
sideways condition was at chance but facial expression (for the
upright condition) was at 80% even though confidence estimates were
well below performance (blindsight). We conclude that the
expression is activating a parallel pathway independent of form
discrimination. EXPT 2) A purple illusory square was displayed to
the left of fixation. After steady fixation it disappeared
completely. Yet if it was then switched off and replaced by a
second square shifted to the right, vivid apparent motion was seen
from the invisible location in frame 1 (p < .01). We conclude
the that even though the 'form' has faded due to fatigue in the
form pathway (V4), the image is extracted by MT and used for
motion.
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