Does "free will" stem from brain noise?

  • June 15, 2014
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Our abil­ity to make choic­es-and mis­takes-might arise from ran­dom fluctua­t­ions in the brain's back­ground elec­tri­cal “noise,” ac­cord­ing to a study from the Uni­vers­ity of Cal­i­for­nia, Da­vis.

“How do we be­have in­de­pend­ently of cause and ef­fec­t?” said Jes­se Beng­son, a post­doc­tor­al re­search­er at the uni­vers­ity's Cen­ter for Mind and Brain and an au­thor on a re­port on the work. “This shows how ar­bi­trary states in the brain can in­flu­ence ap­par­ently vol­un­tary de­ci­sions.”

The brain has a nor­mal lev­el of “back­ground noise,” Beng­son said, as elec­tri­cal ac­ti­vity pat­terns fluc­tu­ate across the brain. In the new stu­dy, de­ci­sions could be pre­dicted based on the pat­tern of brain ac­ti­vity im­me­di­ately be­fore a de­ci­sion was made.

Beng­son sat vol­un­teers in front of a screen and told them to fix their at­ten­tion on the cen­ter, while us­ing elec­tro­en­ce­pha­lo­grapy, or EEG, to rec­ord their brains' elec­tri­cal ac­ti­vity. The vol­un­teers were in­structed to make a de­ci­sion to look ei­ther to the left or to the right when a cue sym­bol ap­peared on screen, and then to re­port their de­ci­sion.

The cue to look left or right ap­peared at ran­dom in­ter­vals, so the vol­un­teers could not con­sciously or un­con­sciously pre­pare for it.

The brain has a nor­mal lev­el of “back­ground noise,” Beng­son said, as elec­tri­cal ac­ti­vity pat­terns fluc­tu­ate across the brain. The re­search­ers found that the pat­tern of ac­ti­vity in the sec­ond or so be­fore the cue sym­bol ap­peared-be­fore the vol­un­teers could know they were go­ing to make a de­ci­sion-could pre­dict the likely out­come of the de­ci­sion.

“The state of the brain right be­fore pre­s­enta­t­ion of the cue de­ter­mines wheth­er you will at­tend to the left or to the right,” Beng­son said.

The ex­pe­ri­ment builds on a fa­mous 1970s ex­pe­ri­ment by Ben­ja­min Li­bet, who meas­ured brain elec­tri­cal ac­ti­vity im­me­di­ately be­fore a vol­un­teer made a de­ci­sion to press a switch in re­sponse to a vis­u­al sig­nal. He found brain ac­ti­vity im­me­di­ately be­fore the vol­un­teer re­ported de­cid­ing to press the switch.

The new re­sults build on Li­bet's find­ing, be­cause they pro­vide a mod­el for how brain ac­ti­vity could pre­cede de­ci­sion, Beng­son said. Ad­di­tion­al­ly, Li­bet had to rely on when vol­un­teers said they made their de­ci­sion. In the new ex­pe­ri­ment, the ran­dom tim­ing means that “we know peo­ple aren't mak­ing the de­ci­sion in ad­vance,” Beng­son said.

Li­bet's ex­pe­ri­ment raised ques­tions of free will-if our brain is pre­par­ing to act be­fore we know we are go­ing to act, how do we make a con­scious de­ci­sion to act? The new work, though, shows how “brain noise” might ac­tu­ally cre­ate the open­ing for free will, Beng­son said.

“It in­serts a ran­dom ef­fect that al­lows us to be freed from sim­ple cause and ef­fect,” he said. The work is pub­lished on­line in the Jour­nal of Cog­ni­tive Neu­ro­sci­ence.

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Source : http://www.world-science.net

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