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.

Identification of the second of two targets (T2) is impaired when presented shortly after the first (T1). This attentional blink (AB) is thought to arise from a delay in T2 processing during which T2 is vulnerable to masking. Conventional studies have measured T2 accuracy which is constrained by the 100% ceiling. We avoided this problem by using a dynamic threshold-tracking procedure that is inherently free from ceiling constraints. In two experiments we examined how AB magnitude is affected by three masking-related factors: (a) presence/absence of T2 mask, (b) T2-mask stimulus onset asynchrony (SOA), and (c) level of T2 impoverishment (signal-to-noise ratio [SNR]). In Experiment 1, overall accuracy decreased with T2-mask SOA. The magnitude of the AB, however, was invariant with SOA and with mask presence/absence. Experiment 2 further showed that the AB was invariant with T2 SNR. The relationship among mask presence/absence, SOA, and T2 SNR and the AB is encompassed in a qualitative model.