Editorial review: November 12, 2026
Do your thoughts cause your behavior? That might sound like a silly question at first. Of course, you feel thirsty, you know that taking a drink will quench your thirst, so you move your arm to pick up your glass and drink some water. It’s obvious that your conscious thoughts about being thirsty and knowing that water will make you feel better caused that action, right?
Some experiments suggest that processes outside conscious awareness contribute to action and to our sense of agency. What those findings mean for everyday decisions is debated. Simple laboratory movements do not settle the broader question of whether, or how, conscious thought causes behavior.
What is the question being tested?
The relationship between mind and body is a philosophical question as well as a scientific one. Epiphenomenalism is one philosophical view: it treats conscious experience as accompanying physical processes without itself causing them. It is not the only possible account, and the experiments below do not establish a consensus in its favor.
A useful distinction is between observing brain activity, measuring when someone reports an intention and explaining what causes a considered choice. Those are different questions. A study can inform the first two without resolving the third.
Push the button
In Libet and colleagues’ 1983 experiment, participants made a simple voluntary movement while researchers recorded electrical brain activity and asked them to report the timing of their intention. The readiness potential preceded the reported intention. The measurement depended partly on a participant’s retrospective timing judgment, which is one reason interpretation requires care.
The readiness potential is a pattern of electrical activity associated with preparing a movement. Its occurrence before the reported intention is not the same as identifying an unconscious decision at a precise moment. The retrospective timing judgment and the interpretation of the signal remain important limits when discussing this experiment.
Is that my hand?
A different question concerns how people recognize an action as their own. Researchers can alter visual feedback while a person moves, then examine whether the person notices the mismatch and how they describe it. This tests a limited laboratory situation, not whether people consciously control every everyday choice.
In Torsten Nielsen’s 1963 drawing experiment, a mirror allowed participants to see another person’s hand while believing it was their own. When both hands followed a straight line, participants experienced the visible movement as voluntary. The experiment then introduced a mismatch by having the visible hand curve to the right.
Participants still experienced the visible hand as their own, but described the deviating movement as involuntary while their actual hand compensated in the other direction. This distinguishes ownership of the seen hand from the feeling of controlling its movement. It does not show that participants consciously chose the crooked line, and the abstract does not establish a percentage for that claim.
Why does this matter?
These experiments raise questions about the timing of intention and how people judge their own actions. They should not be generalized into a claim that all decisions are unconscious or that people cannot change a habit. A simple movement or altered-feedback task differs from planning a project, weighing reasons or revising a decision.
As a practical application, notice what else is happening when a routine fails: competing demands, missing prompts, fatigue or an unclear next step. You can test a change in those conditions without claiming that a neuroscience experiment proved it will work. Continue with practical approaches to behavior change for examples.
Sources and further reading: Libet and colleagues’ 1983 experiment; Matsuhashi and Hallett’s study of intention timing.
Continue exploring the challenge of behavior change.