12 novembre 2014

Quand ton cerveau décide sans toi...

Cet article qui traite du fonctionnement de notre cerveau est tout simplement fascinant. Je ne veux pas le citer en entier, je me contente de quelques extraits et citations pour vous donner envie d'en savoir plus:

Responses were so biased in favor of each team that the researchers came to a rather startling conclusion: “The data here indicate there is no such ‘thing’ as a ‘game’ existing ‘out there’ in its own right which people merely ‘observe.’ ” Everyone was seeing the game they wanted to see. But how were they doing this? They were, perhaps, an example of what Leon Festinger, the father of “cognitive dissonance,” meant when he observed “that people cognize and interpret information to fit what they already believe.”


In watching and interpreting the game footage, the students were behaving similarly to children shown the famous duck-rabbit illusion, pictured above. When shown the illusion on Easter Sunday, more children see the rabbit, where on other Sundays they are more likely to see the duck.1 The image itself allows both interpretations, and switching from seeing one to the other takes some effort. 

(...) But while everyone, at some point, can be made to see duck-rabbit, there is one thing that no one can see: You cannot, no matter how hard you try, see both duck and rabbit at once.

(...) The structure of the brain, she notes, is such that there are many more intrinsic connections between neurons than there are connections that bring sensory information from the world. From that incomplete picture, she says, the brain is “filling in the details, making sense out of ambiguous sensory input.” The brain, she says, is an “inference generating organ.” She describes an increasingly well-supported working hypothesis called predictive coding, according to which perceptions are driven by your own brain and corrected by input from the world. There would otherwise simple be too much sensory input to take in. “It’s not efficient,” she says. “The brain has to find other ways to work.” So it constantly predicts. When “the sensory information that comes in does not match your prediction,” she says, “you either change your prediction—or you change the sensory information that you receive.”

(...) We form our beliefs based on what comes to us from the world through the window of perception, but then those beliefs act like a lens, focusing on what they want to see.

(...) Numerous studies have suggested a biased neural signature in subjects when they see images of people from their own racial in-group. But now tell subjects the people in those images have been assigned to a fictitious “team,” to which they also belong. “In that first 100 milliseconds or so, we’re presented with a rabbit-duck problem,” says Jay Van Bavel, a professor of psychology at NYU. Are you looking at someone from your own team, or someone from a different race? In Van Bavel’s study, suddenly it is the team members that are getting more positive neuronal activity, virtually rendering race invisible (almost as if, per duck-rabbit, we can only favor one interpretation at a time).

(...) As Kornmeier described to me, even the earliest activity in the eyes and early visual systems betray top-down influence—and the information flow can by no means assumed to be one-way. They suggest that even if we do not notice duck and rabbit, our brain may have actually registered the unreliability of the image subconsciously, and decided, in effect, not to spread the news. In this view, your brain itself is in on the trick. The only dupe left in the room is you.

None of which bodes well for the idea that policy or other debates can be solved by simply giving people accurate information. As research by Yale University law and psychology professor Dan Kahan has suggested, polarization does not happen with debates like climate change because one side is thinking more analytically, while the other wallows in unreasoned ignorance or heuristic biases.9 Rather, those subjects who tested highest on measures like “cognitive reflection” and scientific literacy were also most likely to display what he calls “ideologically motivated cognition.” They were paying the most attention, seeing the duck they knew was there.

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