change blindness

   A term used since the 1970s to refer to the relatively poor ability of humans to detect large changes to a visually perceived object or scene. Experiments making use of manipulated photographs, motion pictures, live interactions, and other media indicate that unless a change to a visual scene produces a localizable change at a specific position on the retina, humans tend to have difficulty detecting this change. The notion of change blindness can perhaps be illustrated best by reference to a classic experiment conducted by the American psychologists Daniel J. Simons and Daniel T. Levin, in which unsuspecting pedestrians were approached by a researcher asking for directions. During the ensuing verbal exchange, two other researchers carrying a door passed between them, blocking the pedestrian's view, and allowing the first researcher to swap places with one of the researchers carrying the door. Thus the pedestrian, having begun a conversation with one person, is interrupted, after which he continues his conversation with a different person. The extraordinary nature of this exchange notwithstanding, it was found that some 50% of the subjects failed to detect the switch. Based on findings like these, it has been suggested that the human perceptual system preserves relatively little visual information in between views of a single scene, especially when the interruption takes the form of saccadic eye movements, blinks, blank screens, movie cuts, or other artificial transitions. In addition, it has been suggested that detailed visual representations are not stored in the memory as observers go from one view to the next. It is not clear who coined the term change blindness, but the American psychologist George W. McConkie, who during the late 1970s studied changes made to words and texts during periods of saccadic eye movement, is generally acknowledged as one of the earliest pioneers of the research on change blindness. Conceptually and phenomenologically, change blindness is related to * inattentional blindness, * repetition blindness, *inattentional deafness, * auditory deafness, and * tactile insensitivity. On the basis of psychological and philosophical studies in areas such as these a new brand of scepticism has been developed (see the entry Grand illusion argument).

   References

   Levin, D.T. (2002). Change blindness blindness as visual metacognition.In: Is the visual world a grand illusion? Edited by Noë, A. Thorverton: Imprint Academic.

   McConkie, G.W., Currie, C.B. (1996). Visual stability across saccades while viewing complex pictures. Journal of Experimental Psychology: Human Perception and Performance, 22, 563-581.

   Simons, D., Levin, D. (1997). Change blindness. Trends in Cognitive Sciences, 4, 147-155.