Induced Failures of Visual Awareness
Daniel J. Simons, University of Illinois at Urbana-Champaign, Champaign IL, Canada.
Ronald A. Rensink, University of British Columbia, Vancouver BC, Canada.

Journal of Vision, 3: 1x. 2003.   [web]


Research over the past half century has produced extensive evidence that observers cannot report or retain all of the details of their visual world from one moment to the next. During the past decade, a new set of studies has illustrated just how pervasive these limits are. For example, early evidence for the failure to detect changes to simple dot patterns (Phillips, 1974) and arrays of letters (Pashler, 1988) generalizes to more naturalistic displays such as photographs and motion pictures (e.g., Levin & Simons, 1997; Rensink, O'Regan, & Clark, 1997; see Rensink, 2002 for a recent review). This failure to report changes (change blindness) can be induced in both simple and naturalistic displays, whenever the change co-occurs with a visual disruption such as an eye movement (Currie, McConkie, Carlson-Radvansky, & Irwin, 1995; Hollingworth, Schrock, & Henderson, 2001), image shift (Blackmore, Brelstaff, Nelson, & Troscianko, 1995), flashed blank screen (Rensink et al., 1997), blink (O'Regan, Deubel, Clark, & Rensink, 2000), transient (O'Regan, Rensink, & Clark, 1999; Rensink, O'Regan, & Clark, 2000), movie cut or pan (Levin & Simons, 1997; Simons, 1996), or an occlusion event (Levin, Simons, Angelone, & Chabris, 2002; Simons & Levin, 1998). Change blindness can also occur in the absence of a disruption, provided the change occurs gradually enough that it does not attract attention (Simons, Franconeri, & Reimer, 2000).

Failures of visual awareness have been induced in a number of ways. For example, observers often fail to report a visible but unexpected stimulus when attention is focused on some other object or event in the display (inattentional blindness). As for change blindness, inattentional blindness occurs for both simple (Mack & Rock, 1998; Most et al., 2001) and naturalistic stimuli (Simons & Chabris, 1999). Similarly, repeated instances of an item often go undetected when embedded in a rapid sequence (repetition blindness), a phenomenon that occurs for both words and pictures (Kanwisher, 1987; Kanwisher & Potter, 1990). Observers can also fail to detect a stimulus in a rapid stream of stimuli provided they had to perform an attention-demanding task shortly before the stimulus appeared (Shapiro, Arnell, & Raymond, 1997). The surprisingly large variety of conditions that induce failures of conscious perception reinforces the broad conclusion that we are often unaware of what would otherwise be fully-visible stimuli.

Along with an increased appreciation of the limitations of visual awareness has come a renewed interest in using these limitations to explore the nature of the representations and processes underlying our visual experience. Are these limitations due to failures of perception? Of attention? Of memory? What is preserved with and without awareness?

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