Neuroscience
The scientist Benjamin Libet shocked the world in 1985 when he published research showing that preparatory brain activity occurs several hundred milliseconds prior to when people consciously choose to move.
His experiment suggested free will is an illusion. But there were problems with this interpretation. For example, the apparent lead time of the preparatory brain activity was so short that some critics suggested it could be accounted for by the inaccuracy of people's reports of when they'd made their conscious decisions to move.
Now, using modern brain imaging methods, Chun Siong Soon and colleagues have replicated and extended Libet's famous study - once again reinforcing the notion that our sense of free will is an illusion.
Participants had their brains scanned while they decided to press a button with their right or left index fingers. Participants referred to a constant stream of changing letters, visible on a screen, to indicate when they'd made their decision. Around ten seconds before participants reported making their conscious decision, patterns of brain activity in two areas correlated with the decision they would go on to make. These regions were in the frontopolar cortex and the parietal cortex.
Unlike Libet's study, which reported non-specific preparatory activity, the current experiment showed it was possible to use brain activity to discern which of two options a person was going to choose from, well before they consciously knew which choice they'd made.
Meanwhile, activity in the same movement-related brain area reported by Libet - the supplementary motor area - predicted when the participants would move, up to five seconds before they consciously decided to.
"Thus a network of high-level control areas can begin to shape an upcoming decision long before it enters awareness," the researchers concluded.
Link to earlier related Digest item.
Link to another related Digest item.
Link to essay arguing free will is not an illusion.
Link to recent journal special issue on free will.
_________________________________
Soon, C.S., Brass, M., Heinze, H., Haynes, J. (2008). Unconscious determinants of free decisions in the human brain. Nature Neuroscience DOI: 10.1038/nn.2112
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
- Exposing Some Holes In Libet's Classic Free Will Study
Benjamin Libet's classic 1983 experiment purported to show that preparatory brain activity precedes our conscious decision to move - a controversial finding interpreted by some as evidence that free will is illusory. In Libet's study, participants...
- Want To Make A Complicated Decision? Keep Thinking
"Want to make a complicated decision? Just stop thinking", was one of hundreds of headlines spawned by a study published in 2006 by Ap Dijksterhuis and colleagues. The team of Dutch researchers reported that students made "better" decisions after being...
- Brain Scan Can Read Your Intentions
Researchers have shown they can read a person's intentions from the patterns of activity in the front of their brain. John-Dylan Haynes and colleagues said their findings could have important technical and clinical applications, “such as the further...
- Ouch, That's Expensive!
As well as hurting your wallet, your brain expects an expensive product to cause you pain too. Researchers have found that in terms of brain activity, whether or not we choose to make a purchase is reflected in a trade-off between regions of the brain...
- To Do Or Not To Do...
...that is the question asked by Brass and Haggard (2007) in their recently published paper, which speaks of "free will" in the abstract [of their article]: The mental control of action has an enduring scientific interest, linked to the philosophical...
Neuroscience
Libet Redux: Free will takes another hammering
The scientist Benjamin Libet shocked the world in 1985 when he published research showing that preparatory brain activity occurs several hundred milliseconds prior to when people consciously choose to move.His experiment suggested free will is an illusion. But there were problems with this interpretation. For example, the apparent lead time of the preparatory brain activity was so short that some critics suggested it could be accounted for by the inaccuracy of people's reports of when they'd made their conscious decisions to move.
Now, using modern brain imaging methods, Chun Siong Soon and colleagues have replicated and extended Libet's famous study - once again reinforcing the notion that our sense of free will is an illusion.
Participants had their brains scanned while they decided to press a button with their right or left index fingers. Participants referred to a constant stream of changing letters, visible on a screen, to indicate when they'd made their decision. Around ten seconds before participants reported making their conscious decision, patterns of brain activity in two areas correlated with the decision they would go on to make. These regions were in the frontopolar cortex and the parietal cortex.
Unlike Libet's study, which reported non-specific preparatory activity, the current experiment showed it was possible to use brain activity to discern which of two options a person was going to choose from, well before they consciously knew which choice they'd made.
Meanwhile, activity in the same movement-related brain area reported by Libet - the supplementary motor area - predicted when the participants would move, up to five seconds before they consciously decided to.
"Thus a network of high-level control areas can begin to shape an upcoming decision long before it enters awareness," the researchers concluded.
Link to earlier related Digest item.
Link to another related Digest item.
Link to essay arguing free will is not an illusion.
Link to recent journal special issue on free will.
_________________________________
Soon, C.S., Brass, M., Heinze, H., Haynes, J. (2008). Unconscious determinants of free decisions in the human brain. Nature Neuroscience DOI: 10.1038/nn.2112
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
- Exposing Some Holes In Libet's Classic Free Will Study
Benjamin Libet's classic 1983 experiment purported to show that preparatory brain activity precedes our conscious decision to move - a controversial finding interpreted by some as evidence that free will is illusory. In Libet's study, participants...
- Want To Make A Complicated Decision? Keep Thinking
"Want to make a complicated decision? Just stop thinking", was one of hundreds of headlines spawned by a study published in 2006 by Ap Dijksterhuis and colleagues. The team of Dutch researchers reported that students made "better" decisions after being...
- Brain Scan Can Read Your Intentions
Researchers have shown they can read a person's intentions from the patterns of activity in the front of their brain. John-Dylan Haynes and colleagues said their findings could have important technical and clinical applications, “such as the further...
- Ouch, That's Expensive!
As well as hurting your wallet, your brain expects an expensive product to cause you pain too. Researchers have found that in terms of brain activity, whether or not we choose to make a purchase is reflected in a trade-off between regions of the brain...
- To Do Or Not To Do...
...that is the question asked by Brass and Haggard (2007) in their recently published paper, which speaks of "free will" in the abstract [of their article]: The mental control of action has an enduring scientific interest, linked to the philosophical...