Configural masking of faces: Evidence for high-level interactions in face perception

Abstract

The perception of a stimulus can be impaired when presented in the context of a masking pattern. To determine the timing and the nature of face processing, the effect of various masks on the discriminability of faces was investigated. Results reveal a strong configural effect: the magnitude of masking depends on the similarity between mask and target. Masking is absent for non-face masks (noise, houses), modest for scrambled and inverted faces and strongest for upright faces, even when they differ in size, gender or viewpoint from the targets. This suggests an extra-striate location for the masking (possibly FFA). Reduced but significant masking for isolated face parts (internal features or head shape) is consistent with holistic computations in face perception. The duration over which a face mask can impair face discrimination (130 ms) is markedly longer than previously assumed and is sufficient for iterative and feedback computations to be part of face processing.

Temporal Limitations in Object Processing Across the Human Ventral Visual Pathway

“…These estimates of temporal processing capacity are not necessarily equivalent because the visual system may differ in its capacity to process a single object and multiple objects. This is evidenced by the fact that a target face is more effectively masked by another face than by a visual noise pattern (Loffler et al 2005). In general, our estimates of temporal processing capacity seem to be consistent with previous neurophysiological and neuroimaging studies of objectselective areas and provide novel evidence that high-level areas are sensitive to much lower temporal rates of visual information than early areas.…”

“…People can perceive low-level motion and flicker at rates as high as 30 -50 Hz (Kelly 1961(Kelly , 1979), yet object recognition begins to decline at modest rates of ϳ8 -10 items/s (McMains and Somers 2004;Potter 1975). Recognition of a target face can be disrupted by a subsequent visual mask at much longer delays (upward of 133 ms) if the mask consists of an intact face rather than a scrambled face or visual noise (Loffler et al 2005). These results are consistent with the notion that competitive interactions between object representations occur over a more extended time period than low-level interactions.…”

Facial expression discrimination varies with presentation time but not with fixation on features: A backward masking study using eye-tracking

“…Mask comparison for each group revealed that the upright and inverted neutral-face masks were equally effective at preventing further processing of the facial expressions, except for neutral faces presented for 50 ms. Backward masking in face identity discrimination tasks has been shown to be more effective (i.e., to yield more disruption) if the mask is configurally similar to the target (Loffler et al, 2005). In contrast, at 50 ms presentation, we found higher performance for neutral faces when an upright mask was used compared to an inverted mask.…”

Global Shape Processing Deficits Are Amplified by Temporal Masking in Migraine

“…The temporal window over which a mask exerts its effect is thought to reflect the duration of the underlying computation. 35,36,46 If migraineurs had a processing delay, the masking functions should be shifted horizontally and the peak masking effect would be seen for longer SOAs. Such a shift clearly is not supported by the data, and the peak SOA is the same for controls and migraineurs.…”