Change blindness, representations, and consciousness: Reply to Noë

Abstract

Our recent opinion article [1xChange blindness: past, present, future. Simons, D.J. and Rensink, R.A. Trends Cogn. Sci. 2005; 9: 16–20Abstract | Full Text | Full Text PDF | PubMed | Scopus (489)See all References][1] examined what change blindness can and cannot tell us about visual representations. Among other things, we argued that change blindness can tell us a lot about how visual representations can be used, but little about their extent. We and others found the ‘sparse representations’ view appealing (and still do), and initially made the overly strong claim that change blindness supports the conclusion of sparse representations [2xTo see or not to see: the need for attention to perceive changes in scenes. Rensink, R.A. et al. Psychol. Sci. 1997; 8: 368–373CrossRefSee all References, 3xChange blindness. Simons, D.J. and Levin, D.T. Trends Cogn. Sci. 1997; 1: 261–267Abstract | Full Text PDF | PubMedSee all References]. We wrote our article because change blindness continues to be taken as evidence for sparse – or even absent – representations, and we used O'Regan and Noe's influential paper [4xA sensorimotor approach to vision and visual consciousness. O'Regan, J.K. and Noe, A. Behav. Brain Sci. 2001; 24: 883–975CrossRefSee all References][4] as an example. However, as has been noted for some time [5xComparison blindness. Scott-Brown, K.C. et al. Visual Cogn. 2000; 7: 253–267CrossRefSee all References, 6xFailures of retrieval and comparison constrain change detection in natural scenes. Hollingworth, A. J. Exp. Psychol. Hum. Percept. Perform. 2003; 29: 388–403CrossRef | PubMed | Scopus (105)See all References, 7xBeyond the grand illusion: what change blindness really teaches us about vision. Noe, A. et al. Visual Cogn. 2000; 7: 93–106CrossRefSee all References, 8xCurrent approaches to change blindness. Simons, D.J. Visual Cogn. 2000; 7: 1–15CrossRefSee all References], this conclusion is logically flawed: lack of ability need not be caused by lack of representation.In his letter [9xSee all References][9], Noe agreed that change blindness does not logically require sparse representations, but also claimed that the non-representationist view ‘does a better job of explaining’ change blindness. He further argued that ‘the existence of detailed internal representations does not (and could not) explain visual consciousness.’ His letter also implied that we had leapt to a non-representationist conclusion based on evidence for change blindness.However, we never abandoned the idea that representations underlie our conscious experience even though we did argue for sparse representations. In fact, we have argued for ways in which sparse representations could support our subjective impressions [10xThe dynamic representation of scences. Rensink, R.A. Visual Cogn. 2000; 7: 17–42CrossRefSee all References][10]. We believe that visual representations are necessary to explain some aspects of conscious experience. For example, people do detect most changes eventually, and conscious change detection requires conscious use of representations. If, according to the non-representationist view, change blindness occurs because representations do not contribute to awareness, then conscious change detection should be impossible.Given that change blindness is logically consistent with either the presence or the absence of representations and that consciously accessible representations are needed to detect changes, the non-representationist perspective is not objectively better able to explain all of the evidence. Noe also reiterated the claim that the non-representationist perspective predicted change blindness. However, the non-representationist perspective and evidence of change blindness both existed for decades before either came to prominence, so the idea that one predicted the other is unsupported.Change blindness can occur for many reasons other than just from the lack of visual representations [1xChange blindness: past, present, future. Simons, D.J. and Rensink, R.A. Trends Cogn. Sci. 2005; 9: 16–20Abstract | Full Text | Full Text PDF | PubMed | Scopus (489)See all References, 8xCurrent approaches to change blindness. Simons, D.J. Visual Cogn. 2000; 7: 1–15CrossRefSee all References]. Noe's commentary leads us to suggest a more tractable question: why do representations sometimes lead to consciousness and other times not? This is an empirical question, and change blindness can contribute to an answer.