Motion-induced blindness measured objectively
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Motion-induced blindness measured objectively Peter Kramer & Stefano Massaccesi & Luca Semenzato & Stefano Cecchetto & Paola Bressan
Published online: 31 August 2012 # Psychonomic Society, Inc. 2012
Abstract During central fixation, a moving pattern of nontargets induces repeated temporary blindness to even salient peripheral targets: motion-induced blindness (MIB). Hitherto, behavioral measures of MIB have relied on subjective judgments. Here, we offer an objective alternative that builds on earlier findings regarding the effects of MIB on the detectability of physical target offsets. We propose a small modification of regular MIB displays: Following a variable duration (lead time), one of the targets is physically removed. Subjects are to respond immediately afterward. We hypothesize that illusory target offsets, caused by MIB, are mistaken for physical target offsets and that errors should thus increase with lead time. Indeed, for both nonsalient and salient targets, we found that detection accuracy for physical target offsets dramatically decreased with lead time. We conclude that target offset detection accuracy is a valid objective measure of MIB. With our method, effects of guessing are minimal, and the fitting of psychometric functions is straightforward. In principle, a staircase extension— for more efficient data collection—is also possible. Keywords Motion-induced blindness . Objective measure . Perceptual filling-in . Awareness
Electronic supplementary material The online version of this article (doi:10.3758/s13428-012-0246-5) contains supplementary material, which is available to authorized users. P. Kramer (*) : S. Massaccesi : L. Semenzato : S. Cecchetto : P. Bressan Dipartimento di Psicologia Generale, Università di Padova, Via Venezia 8, 35131 Padova, Italy e-mail: [email protected]
Introduction If central fixation is maintained, a moving pattern of nontarget shapes (henceforth, inducers) provokes repeated temporary blindness to even salient peripheral target shapes—that is, motion-induced blindness (MIB; Bonneh, Cooperman, & Sagi, 2001). The effect is most likely due to a failure of awareness (Donner, Sagi, Bonneh, & Heeger, 2008; Klotz & Ansorge, 2007; Mitroff & Scholl, 2004, 2005; MontaserKouhsari, Moradi, Zandvakili, & Esteky, 2004) involving the thalamus (Wilke, Mueller, & Leopold, 2009) and various areas of the visual cortex (Donner et al., 2008; Libedinsky, Savage, & Livingston, 2009; Schölvinck & Rees, 2009). So far, the behavioral measurement of MIB has relied on subjective judgments that are usually provided with buttonpresses. Two measures can be found in the literature (and in the related literature on perceptual filling-in): (1) the time until the target is judged to disappear for the first time and (2) the proportion of the trial during which the target is judged invisible. The two measures tend to lead to similar results (Hsu, Yeh, & Kramer, 2004). In the present study, we seek an objective version of the first measure. In this version, unlike in subjective ones, responses are
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