Sound Research WIKINDX

Discussing Libet's (1985) experiment. While we prefer to believe that we have willed our hand to rise, our intention, there is a precursor in the subconscious, the readiness potential, that can be measured using EEG and that precedes the hand movement and the reported time at which subjects noted their intention to lift the hand. The conclusion is that intention (and thus free will?) is manufactured after the event. See also (Rosenberg 2018, p.99).

Detailing a set of experiments by Libet helping to explain how our brain builds a consciousness of the present and the time delay involved.

• Stimulating the brain directly, an electrical impulse must be applied for at least 500 milliseconds to produce a perception (see, for example Libet 1985). Shorter impulses had no effect neither did increasing the intensity (with shorter times). Sensation can be detected by the brain within 500msecs but the subject is not consciously aware of it (e.g. we can react 'instinctively').
• Stimulate the skin then, 200 milliseconds after, stimulate the brain – the skin stimulation is not perceived but is masked by the brain stimulation. The brain edits past events to give an impression of the 'present'.
• Stimulate the brain then, 200 milliseconds later, stimulate the skin. Brain stimulus is perceived after about 500msecs but the skin stimulus is perceived as being before the brain stimulus. A temporal reordering: "There is no guarantee that the order in which we perceive events actually corresponds to the order of their occurrence" (Westerhoff 2011, p.100).