"Mind Time: The Temporal Factor in Consciousness" by Benjamin Libet

After a lecture in Göteborg by the neuroscientist Benjamin Libet in 1993, the Göteborg-Post carried the headline, ‘Now it has been proven: we are all somewhat behind’. The paper was referring to Libet’s celebrated discovery that the neural precursors of some voluntary actions occur before the conscious awareness of the decision to act. In a series of experiments in the 1980s, Libet showed that in an experimental situation in which subjects were asked to perform a simple voluntary action – raising a finger – these acts were preceded by a rise in electrical activity in the area of the brain responsible for the causation of action, called the ‘readiness potential’ (RP). But the striking discovery is that while the RP is activated 550 msec before the action, the subject’s awareness of their decision to act occurs only 150-200 msec before the action. The conclusion is drawn that the causes of our actions in our brains occur fractionally earlier than our conscious awareness of deciding to do them. Hence the frequent description of the result of Libet’s experiments, that we are ‘living in the past’.