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Niko A. Busch, Ingo Fruend, Christoph S. Herrmann; Electrophysiological evidence for different qualities of change detection and change blindness. Journal of Vision 2007;7(9):648. doi: 10.1167/7.9.648.
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© ARVO (1962-2015); The Authors (2016-present)
Studies on change blindness, the failure to detect large changes in a visual display, have provided new insights on perception, attention, and visual experience. It is currently debated whether changes can be detected (“sensed”) preattentively without a corresponding visual experience. While some authors have claimed that sensing and visual experience are separate processes, others hold that there is merely a quantitative difference, with sensing having a more liberal response criterion. While electrophysiological (EEG) experiments can potentially dissociate the neurophysiological processes involved, most previous EEG studies have used only simple, abstract stimuli and did not differentiate between different types of change detection. The present study investigated qualitative and quantitative electrophysiological differences between sensing and visual experience. On each trial an array of 4×4 colored drawings of everyday objects was presented for 615 ms, replaced by a blank screen for 80 ms, and presented again for 615 ms. The identity of one object was changed in the second display on half of the trials. Participants reported whether or not they detected any change, irrespective of whether or not they could report the object's identity. On detected change trials, participants were additionally asked to identify the object. While detection can be performed on the basis of sensing, identification requires a visual experience of the change. A negative deflection of the event-related potential (ERP) at posterior sites around 200 ms after the change was found for identification and, with smaller amplitude, as well for detection. Identification was associated with several ERP components contralateral to the side of a change, such as the N2PC. This component was completely absent for changes that were only detected and for change blindness. This qualitative electrophysiological difference between change detection and identification supports the claim that sensing and visual experience of a change are indeed separate qualities of perception.
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