Adaptation aftereffects are the tendency to perceive an ambiguous target stimulus, which follows an adaptor
stimulus, as different from the adaptor. A duration dependence of face adaptation aftereffects has been demonstrated for
durations of at least 500ms, for identity related judgments. Here we describe the duration dependence of the adaptation aftereffects
of very brief (11.7ms-500ms) backwardly masked faces, on both expression and identity category judgments of
ambiguous target faces. We find significant aftereffects at minimum duration 23.5ms for emotional expression, and 47ms
for identity, but these are abolished by backward masking with an inverted face, although these same adaptors can be correctly
categorized above chance.
The presence of a short duration adaptation effect in expression might be mediated by rapid transfer of low spatial frequency
(LSF) information. We tested this possibility by comparing aftereffects in low pass and high pass filtered ambiguous
targets, and found no evidence of independent adaptation of a LSF specific channel.