each subject to choose a random moment to flick their wrist while he measured the associated activity in their brain; in particular, the build-up of electrical signal called the readiness potential (after German Bereitschaftspotential, which was discovered by Kornhuber & Deecke in 1965.). Although it was well known that the readiness potential reliably preceded the physical action, Libet asked whether it could be recorded before the conscious intention to move. To determine when subjects felt the intention to move, he asked them to watch the second hand of a clock. After making a movement, the volunteer reported the time on the clock when they first felt the conscious intention to move; this became known as Libet's W time. Libet found that the unconscious brain activity of the readiness potential leading up to subjects' movements began approximately half a second before the subject was aware of a conscious intention to move. These studies of the timing between actions and the conscious decision bear upon the role of the brain in understanding free will. A subject's declaration of intention to move a finger appears after the brain has begun to implement the action, suggesting to some that unconsciously the brain has made the decision before the conscious mental act to do so. Some believe the implication is that free will was not involved in the decision and is an illusion. The first of these experiments reported the brain registered activity related to the move about 0.2 s before movement onset. However, these authors also found that awareness of action was anticipatory to activity in the muscle underlying the movement; the entire process resulting in action involves more steps than just the onset of brain activity. The bearing of these results upon notions of free will appears complex. Some argue that placing the question of free will in the context of motor control is too narrow. The objection is that the time scales involved in motor control are very short, and motor control involves a great deal of unconscious action, with much physical movement entirely unconscious. On that basis "…free will cannot be squeezed into time frames of 150–350 ms; free will is a longer term phenomenon" and free will is a higher level activity that "cannot be captured in a description of neural activity or of muscle activation…" The bearing of timing experiments upon free will is still under discussion. More studies