Abstract
Change blindness refers to the inability to detect visual changes if introduced together with an eye-movement, blink, flash of light, or with distracting stimuli. Evidence of implicit detection of changed visual features during change blindness has been reported in a number of studies using both behavioral and neurophysiological measurements. However, it is not known whether implicit detection occurs only at the level of single features or whether complex organizations of features can be implicitly detected as well. We tested this in adult humans using intact and scrambled versions of schematic faces as stimuli in a change blindness paradigm while recording event-related potentials (ERPs). An enlargement of the face-sensitive N170 ERP component was observed at the right temporal electrode site to changes from scrambled to intact faces, even if the participants were not consciously able to report such changes (change blindness). Similarly, the disintegration of an intact face to scrambled features resulted in attenuated N170 responses during change blindness. Other ERP deflections were modulated by changes, but unlike the N170 component, they were indifferent to the direction of the change. The bidirectional modulation of the N170 component during change blindness suggests that implicit change detection can also occur at the level of complex features in the case of facial stimuli.
Highlights
Cognitive psychologists have discovered an astounding inability to detect considerable and obvious changes in visual scenes presented after a global transient event, for example an eye-blink or a ‘‘flicker’’ – a brief blank screen with a blink-like effect
Using schematic faces and scattered groups of physically identical features as stimuli, we investigated the implicit detection of changes in facial and non-facial stimuli in the change blindness paradigm while recording event-related potentials (ERPs)
We investigated the implicit detection of changes in visual stimuli containing feature complexes by presenting schematic faces and scrambled faces as stimuli in a change blindness paradigm
Summary
Cognitive psychologists have discovered an astounding inability to detect considerable and obvious changes in visual scenes presented after a global transient event, for example an eye-blink or a ‘‘flicker’’ – a brief blank screen with a blink-like effect. In another study comparing subconsciously presented emotional expressions to neutral ones, the former elicited an enhanced EPN-like response, a response sensitive to emotionally and motivationally salient stimuli, approximately 220 ms after stimulus onset [39] These results among others on non-conscious face-perception [26,40,41,42] indicate that facial features are bound together and that these feature complexes can be detected by the brain, even without awareness of them. In studies measuring change detection performance, it has been shown that socially relevant changes, including changes involving faces, are often detected more than socially neutral ones (gradual changes in facial expressions vs gradual color changes [43]; people vs objects [44]; heads vs objects: [45]) These authors have explained the more efficient change detection in socially relevant stimuli as a result of the interplay between salience and attentional effects. We sought out evidence of implicit change detection in complex facial configurations during change blindness, evidence that was provided by revealing modulation of the face-sensitive N170 ERP response to configural stimulus changes of facial stimuli without explicit behavioral change detection
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