Perceptual conditions necessary to induce change blindness Massimo Turatto, Sandro Bettella, and Carlo Umilta Á University of Padova, Padua, Italy Bruce Bridgeman University of California, Santa Cruz, USA Change blindness is a failure to detect a change in an scene when the change occurs along with some visual disturbances. Disturbances are thought to play a delocalizing role that affects the saliency of the ``target'' transient signal coming from the change location, which would otherwise capture attention and render the change visible. For instance, it is hypothesized that the appearance of new objects in the ``mudsplashes'' paradigm generates transient signals that compete with the target object's transient signal for attracting attention. Thus, experiments using the mudsplashes paradigm do not rule out a possible role of object changes in cap- turing attention. Here, by reversing image contrast polarity, we develop a new paradigm to produce change blindness when a real global transient signal is the only visual event occurring, with no edges added or deleted except in the target object. The results show that transient signals, per se, are able to prevent change detection. However, abrupt transients are not necessary if object change occurs in the zero-contrast phase of a smoothly fading and reappearing image, leaving attention as the only common factor affecting all cases of change blindness. Over the last few years change blindness CB) has emerged as a central method for the study of visual attention. The phenomenon consists of a failure to detect striking changes in a scene when such changes occur simultaneously with a brief visual disruption Simons & Levin, 1997). Following the initial demonstrations of the existence of the phenomenon, more recent work including this paper) concentrates on using the CB effect as a tool to uncover aspects of visual function. Several kinds of visual events can prevent observers from noticing a change in a visual image. For instance, CB is observed if a modification occurs during a VISUAL COGNITION, 2003, 10 2), 233±255 Please address all correspondence to: M. Turatto, Dipartimento di Psicologia Generale, Universita Á di Padova, Via Venezia, 8, 35131 Padova, Italy. E-mail: mturatto@unipd.it This study was supported by grants from CNR and MURST to CU, and by a grant from the University of California Education Program to BB. # 2003 Psychology Press Ltd http://www.tandf.co.uk/journals/pp/13506285.html DOI:10.1080/13506280244000087