First discovered in 1965 by Kornhuber and Deecke, the readiness potential (RP) is a distinctive buildup of neural activity in motor areas of the brain that begins ~500 ms before voluntary movements. In 1983, Libet used the RP as the foundation for his argument against the existence of conscious free will. This argument became known as the classic model of the RP, which interprets the RP as a precursor to the conscious experience of volition and a quantifiable representation of unconscious brain activity preceding spontaneous movements. Although the classic model connected the RP to free will, the significance of the RP remains uncertain. In this presentation, we will discuss two interpretations of the RP as it relates to free will: the aforementioned classic model and the stochastic accumulator model. Since its introduction into the discussion on free will, the classic model has received numerous criticisms that can be encapsulated in “Libet’s paradox”. The paradox states that the conscious experience of volition comes after the brain has already begun preparing to execute the movement. This is paradoxical because it seems impossible to move voluntarily without consciously deciding to move beforehand. In contrast, the stochastic model believes the RP to be an artifact of EEG time locking and averaging of individual trials. Thus, the RP cannot counter the existence of free will since it does not reflect the process of volition. The stochastic model states that movement occurs when random fluctuations in brain activity, combined with a desire to move, overcome a threshold. The RP may be apparent before the conscious decision to move, but the actual neural commitment to initiate movement may happen much closer in time to the onset of the movement itself. In future studies, a holistic approach to EEG analysis may yield greater insights into the RP’s true nature rather than using time-locked data epochs in which movement occurs.
Pak, Joanna; Schurger, Aaron; Roskies, Adina; and Hu, Pengbo, "Brainwaves and Intentions: The Readiness Potential and Its Relation to Free Will" (2020). SURF Posters and Papers. 2.