Decision Time

No sooner do I finally get my article about human nature and political values published in Prospect than a key piece of research cited in the piece gets challenged. A study undertaken in New Zealand has questioned the conclusions of the work of Benjamin Libet, conclusions which had become the cornerstone of how we have come to think about the workings of our brain.

Put simply, Libet’s research, which has been repeated and refined by other neuroscientists, seemed to show that the part of the subject's brain associated with a physical action, for example, pressing a button, showed activity significantly earlier (a few tenths of a second) than the subject became aware of making the decision to act. This research seemed to show that the idea of conscious choice is often an illusion. Whilst we do make conscious decisions which involve forward planning, our day to day actions are automatic. The sense we have of making conscious choices reflect the deep seated need of human beings to make meaning, but it is an illusion. As Robert Heinlen put it ‘man is not a rational animal but a rationalising one’.

But now research by Judy Trevena and Jeff Miller, neuroscientists based in Otago, has questioned Libet’s work.  Their research involved replicating Libet’s experiment but with an important modification. While Libet asked his subjects to press buttons, the New Zealand team allowed subjects to choose whether or not to press. Trevena and Miller then found that the brain activity identified by Libet (so called Readiness Potential) occurred after the subjects had been prompted and before they were aware of making a choice - whether or not they then decided to press the botton.  In other words, it is not that the automatic brain ‘decides’ to act before the conscious brain but that it creates a readiness to act which only gets turned into action by conscious intervention.  Furthermore ,Trevena and Miller claim to show that the brain activity specifically associated with ‘deciding’ to act takes place after the conscious awareness of that decision.

Unsurprisingly, the New Zealand study is causing waves in the neuroscience community. Those who have always been sceptical about Libet are seizing on the new research, while others who claim to have undertaken experiments reinforcing Libet’s conclusions are questioning Trevena ands Miller’s methodology.

Although it can all get quite technical, this is a fascinating debate with social and philosophical as well as scientific ramifications. We are exploring whether we can host a debate here at the RSA. Indeed, if someone would just give us a few tens of thousands of pounds we would love to modernise an old RSA tradition and work with neuroscientists at UCL to replicate the research with a live video link to a Great Room audience.