inattentional blindness

   The term inattentional blindness is indebted to the Latin words in (not) and attentio (attention, notice). It was introduced in or shortly before 1992 by the American psychologists Arien Mack (b. 1931) and Irvin Rock (1922-1995). It is used to denote a failure to consciously perceive a fully visible, but unanticipated object or stimulus because the observer's focus of attention is elsewhere. A classic illustration of the notion of inattentional blindness was reported by the American psychologists Daniel J. Simons and Christopher F. Chabris. They asked 192 test persons to watch a video fragment in which two small groups of people were playing basketball, and to keep count of either the number of passes made by one of the teams or the number of bounce passes versus aerial passes. In different versions of the video fragment a tall woman entered the field carrying a white umbrella, or a shorter woman wearing a gorilla suit. In both versions the woman's on-screen presence lasted 5 s. Afterwards the test persons were asked whether they had noticed anything out of the ordinary taking place on the screen, and on average 46% responded in the negative. Simons and Chabris attribute this failure to detect an ongoing and highly salient, yet unexpected event to inat-tentiveness or 'divided attention'. Since ancient times the phenomenon itself has been used -and misused - by illusionists, stage magicians, and tricksters. In the medico-psychological literature it has been described at least since the era of mesmerism. In the 19th-century hypnotist tradition, for example, inattentiveness constitutes one of the explanatory models for the mediation of "negative hallucinations. It has been suggested that, in a conceptual and phenomenologi-cal sense, inattentional blindness may well be similar to " hypnotic blindness. Other related phenomena are "inattentional deafness, "auditory deafness, " tactile insensitivity, and " change blindness. The notion ofinattentional blindness should not be confused with "visual inattention.

   References

   Mack, A., Rock, I. (1998). Inattentional blindness. Cambridge, MA: MIT Press. Parish, E. (1897). Hallucinations and illusions. A study ofthe fallacies ofperception. London: Walter Scott.

   Simons, D.J., Chabris, C.F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28, 1059-1074.