Benjamin Libet

Benjamin Libet (1916-2007) was a pioneering neurophysiologist in the Department of Physiology at the University of California, San Francisco. Through direct intracranial stimulation of human somatosensory cortex and scalp electroencephalography (EEG), Libet transformed the temporal relationship between neural activity and subjective awareness into a quantitative experimental discipline.

In his classic 1983 Brain study, Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential), Libet asked participants to note the clock position of a revolving spot when they first felt the conscious urge ($W$) to flex their wrist. He found that the slow negative readiness potential (Bereitschaftspotential) began ramping in supplementary motor area 350 to 500 milliseconds before the reported conscious intention $W$, which itself preceded muscle activation by roughly 200 milliseconds. Earlier, Libet also demonstrated that direct cortical stimulation requires roughly 500 milliseconds of sustained pulse-train activity (“neuronal adequacy”) to cross the threshold into conscious sensation, even though the resulting experience is subjectively backdated to the initial peripheral stimulus marker.

Libet defended a biological and field-based view of awareness, proposing late in his career a testable “conscious mental field” emerging from biological brain tissue while retaining a 150-millisecond window for a conscious “veto” over initiated motor urges. Later computational work by Aaron Schurger and Stanislas Dehaene reinterpreted Libet’s early readiness-potential ramp as stochastic neural noise crossing a decision threshold, making Libet’s timing paradigm one of the most productive empirical tests in consciousness science.

Known for. Readiness potential and timing of conscious intention (1983), half-second neural adequacy delay for somatosensory awareness, conscious mental field hypothesis

Coverage on this site

• Why Visual Awareness Lags by 80 Milliseconds in Eagleman, Sejnowski and Schurger's Timing Models November 2026

Related researchers

• DE David EaglemanDepartment of Psychiatry and Behavioral Sciences, Stanford UniversityPostdiction and the 80-millisecond visual integration window (with Terrence Sejnowski), time perception, sensory substitution and livewired neural plasticity Functionalist1 article
• TS Terrence J. SejnowskiComputational Neurobiology Laboratory, Salk Institute / UC San DiegoCo-inventor of the Boltzmann Machine, The Computational Brain (1992), Independent Component Analysis (ICA), The Deep Learning Revolution (MIT Press, 2018) Functionalist4 articles
• AS Aaron SchurgerLPNC, CNRS, Université Grenoble AlpesThe stochastic accumulator model of the readiness potential, critique of causal reading of neural precursors, error and awareness dynamics Critic1 article
• FB František BaluškaUniversity of BonnCellular consciousness, subcellular nanobrains, plant neurobiology, sentient cells as units of physiology Biological naturalist1 article
• TB Tristan A. BekinschteinDepartment of Psychology / Consciousness and Cognition Lab, University of CambridgeClinical biomarkers of consciousness, local-global auditory paradigm, transitions from wakefulness to sedation, neural dynamics of awareness Biological naturalist1 article
• TB Tomas Berjaga-BuisanComputational Neuroscience Group, Center for Brain and Cognition, Universitat Pompeu Fabra, BarcelonaNon-equilibrium thermodynamics of whole-brain models, fluctuation-dissipation theorem violations as a non-invasive consciousness marker Biological naturalist1 article

Benjamin Libet is listed with the other biological naturalists, who hold that consciousness requires living metabolic hardware. The theory family behind that position is set out in the index of consciousness theories. Every researcher covered on this site is indexed in the directory of consciousness researchers.