Inattention blindness

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Inattentional blindness (also blindness due to inattention; English inattentional blindness ) is the non-perception of objects, caused by the limited processing capacity of the human brain .

overview

The non-perception of major changes to objects in the environment is called change blindness (change blindness). Taken together, these findings suggest that only objects and details are perceived or noticed on which attention was directed. The brain has to select which information is relevant and which is less. Only when the attention is directed to a stimulus does it become aware of it. The direction of attention affects the activity of certain brain structures.

Experiments by Mack and Rock

Mack and Rock (1998) initially asked their test subjects to decide whether the horizontal or vertical line of a cross displayed for 200 milliseconds was longer. In the third run of the experiment , another stimulus (e.g. a small square) was unexpectedly displayed. The test subjects were then asked whether they had seen it, which around 25 percent answered in the negative. This "seeing blindness " seems to stem from the fact that the test subjects did not expect the stimulus and concentrated on something else, namely the cross. Mack and Rock call this phenomenon inattentional blindness or inattention blindness in German .

Since they assume that there is no conscious perception without attention , they come to the conclusion that the other stimuli aroused the attention of 75 percent of the test subjects and thus attracted them.

"Gorillas in our midst" (Simons and Chabris)

The study "Gorillas in our midst" (Engl .: Gorillas in Our Midst ) of the University of Illinois shows that urban people even a passing man in gorilla suit can be overlooked. Building on classic studies of divided visual attention and referring to inattentive blindness by Mack and Rock, Simons and Chabris investigated in their gorilla experiment the phenomenon of inattentional blindness for complex objects and events in moving scenes. The results of the investigation suggest that the likelihood of noticing an unexpected object depends both on the similarity of this object to the other objects presented and on the difficulty of the original observation task. Simons and Chabris refer to various studies (including Ulrich Neisser 1979, Grimes 1996, Mack & Rock 1998) which have shown that conscious perception seems to require attention.

The material for Simons 'and Chabris' experiment on the phenomenon of inattention blindness are four videos of 75 seconds each. Each film shows two teams with three players each, one wearing white and the other black t-shirts. The members of each team play a normal orange basketball by throwing or dribbling. After 44 to 48 seconds something unexpected happens: In the Umbrella Woman version , a tall woman walks through the action from left to right with an open umbrella. In the gorilla version, a smaller woman who is completely wrapped in a gorilla costume walks through the picture in the same way. During these unexpected events, the basketball players unwaveringly continue their actions.

The videos are also available in two styles: in a transparent version (transparent condition) and an opaque version (opaque condition) . For the former, the white and black team and the “incident” were first filmed separately, then partially made transparent and superimposed with the help of digital post-processing. For the opaque version, all seven actors were filmed at the same time. The result was four films: Transparent / Umbrella Woman, Transparent / Gorilla, Opaque / Umbrella Woman, Opaque / Gorilla .

tries

The first test arrangement (Transparent / Umbrella Woman) corresponds to that of Neisser (1979), which Simons and Chabris also describe in their article. Before they see a video, the test subjects are given the task of either concentrating on the team in white or the team in black and counting all rallies by the observed team in their heads (easy condition) or counting the thrown and dribbled rallies separately ( hard condition) . After the subjects watched the video and completed their observation assignment, they were asked to write down their numbers. They were then asked if (a) they noticed anything unusual while counting, (b) if they had noticed anything other than the six players, (c) if someone else had appeared in the video, and finally: (d) hurry you see a gorilla (a woman with an umbrella) walking through the picture?

Ultimately, 192 test subjects remained for the evaluation (some had to drop out because they already knew a similar experiment, forgot to count, etc.), of whom, across all of the above versions of the film, 54 percent noticed the "incident" and 46 percent did not . (Simons and Chabris break down the results into transparent and opaque condition, easy and hard condition .) It is interesting that the woman with the umbrella was discovered more often than the woman in the gorilla costume (65% versus 44%). And further: the test subjects who observed the black team noticed the gorilla more often than those who had the white team in the focus of their attention (black 58%, white 27%). However, when it came to discovering the woman with the umbrella, it made only a small difference whether white or black rallies were counted (black 62%, white 69%). The gorilla was black, while the woman with the umbrella was dressed in light colors and stood out from the black and white teams alike.

Results

  • About half of the test persons did not notice a long-lasting, actually very noticeable, but unexpected event when they were busy with an elementary observation task.
  • The level of inattention blindness depends on the difficulty of the observation task.
  • The subjects are more likely to take notice of an unexpected event when it shares essential visual characteristics (such as color) with the situation being observed - a contradiction to the traditional pop-out phenomenon in visual search tasks (and in contrast to Neisser, 1979).
  • Objects can move right through the center of attention (foveal vision) and still will not be "seen" unless we pay special attention to them.

See also

Web links

literature

  • U. Neisser (1979): The Control of Information Pickup in Selective Looking, in: Perception and Its Development: A Tribute to Eleanor J Gibson . Ed. AD Pick (Hillsdale, NJ: Lawrence Erlbaum Associates) pp. 201-219.
  • J. Grimes (1996): On the Failure to Detect Changes in Scenes Across Saccades, in: Perception (Vancouver Studies in Cognitive Science) . Ed. K Akins, volume 2 (New York: Oxford University Press) pp. 89-110.
  • A. Mack, I. Rock (1998): Inattentional Blindness (Cambridge, MA: MIT Press).
  • DJ Simons, CF Chabris (1999): Gorillas in Our Midst: Sustained Inattentional Blindness for Dynamic Events . Perception, 28, pp. 1059-1074 ( pdf ).
  • Interview with Christopher Chabris and Daniel Simon in: New Scientist, No. 2766, pp. 32–33.
  • Ch.Chabris, Daniel Simons. The Invisible Gorilla: How Our Brains Can Be Deceived. Piper 2011.