"Long before it's in the papers"
June 04, 2013

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Brain may prepare decisions in advance

April 15, 2008
Courtesy Nature Journals
and World Science staff

Cer­tain pat­terns of brain ac­ti­vity pre­dict peo­ple’s de­ci­sions up to 10 sec­onds be­fore the peo­ple are aware of them, ac­cord­ing to new re­search that casts fresh doubt on wheth­er we have free will.

Enhanced photo­graph of brain cells un­der mi­cro­sco­pic mag­ni­fi­ca­tion (cour­tesy Li­ver­more Nat'l Lab, Cen­ter for Ac­cel­er­a­tor Mass Spec­t­ro­me­try)


The an­cient de­bate over free will cen­ters on wheth­er it’s an il­lu­sion to be­lieve our thoughts and de­ci­sions are in­de­pend­ent, since our brains really con­sist of atoms bounc­ing around ac­cord­ing to their own rules.

The new study sug­gests the ques­tion­ing may be jus­ti­fied.

Re­search­ers tracked brain ac­ti­vity while peo­ple viewed a stream of let­ters on screen, and then pressed a but­ton. Each par­ti­ci­pant was asked to de­cide freely which of two but­tons to press and when to press it.

Scan­ning the brains with a tech­nique called func­tion­al mag­net­ic res­o­nance im­ag­ing, the in­ves­ti­ga­tors used a sta­tis­ti­cal meth­od known as pat­tern rec­og­ni­tion to ex­am­ine brain ac­ti­vity as­so­ci­at­ed with each choice. Ac­ti­vity in two brain re­gions, called the pre­fron­tal and pa­ri­e­tal cor­tex, pre­dicted which but­ton the per­son would press, they found. These ar­eas have pre­vi­ously been linked to self-re­flec­tion, se­lec­tion amongst choices and ex­ec­u­tive con­trol.

This ac­ti­vity oc­curred up to 10 sec­onds be­fore sub­jects were con­sciously aware of hav­ing made a de­ci­sion, ac­cord­ing to the re­search­ers. The find­ings, they added, sug­gest high-lev­el con­trol ar­eas start to pre­pare an up­com­ing de­ci­sion long be­fore it en­ters con­scious awareness. 

The stu­dy, by John-Dylan Haynes of the Max Planck In­sti­tute for Hu­man Cog­ni­tive and Brain Sci­ences in Leip­zig, Ger­ma­ny and col­leagues, is pub­lished on­line this week in the re­search jour­nal Na­ture Neu­ro­sci­ence.


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Certain patterns of brain activity predict people’s decisions up to 10 seconds before they’re aware of them, according to a new study that casts fresh doubt on whether people have free will. The ancient debate over free will centers on whether it’s an illusion to believe our thoughts and decisions are independent, since our brains ultimately consist of atoms bouncing around according to their own rules. The new study suggests the doubts may be justified. Researchers tracked brain activity while people viewed a stream of letters on screen, and then pressed a button. Each participant was asked to decide freely which of two buttons to press and when to press it. Scanning the brains with a technique called functional magnetic resonance imaging, the investigators used a statistical method known as pattern recognition to examine brain activity associated with each choice. Activity in two brain regions, called the prefrontal and parietal cortex, predicted which button the person was going to press, they found. These areas have previously been found to be involved in self-reflection, selection amongst choices and executive control. This activity occurred up to 10 seconds before subjects were consciously aware of having made a decision, according to the researchers. The findings, they added, suggest high-level control areas start to prepare an upcoming decision long before it enters conscious awareness. The study, by John-Dylan Haynes of the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany and colleagues, is published online this week in the research journal Nature Neuroscience.