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Exp Brain Res (2007) 183:95105 DOI 10.1007/s00221-007-1023-z
RESEARCH ARTICLE
Electrophysiological correlates of stimulus processing in change blindness
Andrea Schankin Edmund Wascher
Received: 18 October 2006 / Accepted: 8 June 2007 / Published online: 5 July 2007 Springer-Verlag 2007
Abstract Change blindnessthe inability to detect salient changes when a distractor event occurs simultaneouslyhas been repeatedly used to investigate the neural correlates of awareness. The fact that the N2pc, which is basically assigned to attention processing, has been observed only for detected changes in such tasks lead to the assumption that this component may also reXect awareness. In contrast to previous electrophysiological studies, we used mudsplashes (experiment 1) or a very short blank (experiment 2) to induce change blindness so that the change was not occluded. A change, regardless of its detection, elicited a reliable N2pc. Successful change detection, however, was reXected in an enhanced amplitude of the N2pc component. Thus, the N2pc cannot be taken as a direct correlate of awareness but rather as a marker for a process that is necessary but not suYcient for awareness. Taking into account the generation of the N2pc in extrastriate visual areas, this Wnding Wts nicely with the recent discussion about reentrant processing as a basis for visual awareness.
Keywords Change blindness Change detection
Selective attention Event-related brain potentials N2pc
Introduction
The investigation of neural correlates of visual awareness is often based on paradigms in which the presentation of physically identical stimuli may lead to conscious perception of particular information (detected) that is also occasionally missed (undetected). DiVerences in neural activity between detected and undetected information in such a task are proposed to reXect neural correlates of conscious processing. Following this logic, functional brain-imaging studies on binocular rivalry (e.g., Tong et al. 1998), visual masking (e.g., Bar et al. 2001), or change blindness (e.g., Beck et al. 2001; Pessoa and Ungerleider 2004) revealed that awareness of visual information is related to selective activations within ventral visual areas. These results suggest that the ventral visual stream, which connects the early visual areas of the visual cortex with higher visual areas located in the temporal lobe, may be a core structure for generating conscious visual experience.
Change blindness refers to the inability of observers to detect salient changes between successively presented...