We infer rather than perceive the moment we decided to act

Psychol Sci. 2009 Jan;20(1):17-21. doi: 10.1111/j.1467-9280.2008.02254.x.


A seminal experiment found that the reported time of a decision to perform a simple action was at least 300 ms after the onset of brain activity that normally preceded the action. In Experiment 1, we presented deceptive feedback (an auditory beep) 5 to 60 ms after the action to signify a movement time later than the actual movement. The reported time of decision moved forward in time linearly with the delay in feedback, and came after the muscular initiation of the response at all but the 5-ms delay. In Experiment 2, participants viewed their hand with and without a 120-ms video delay, and gave a time of decision 44 ms later with than without the delay. We conclude that participants' report of their decision time is largely inferred from the apparent time of response. The perception of a hypothetical brain event prior to the response could have, at most, a small influence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Attention
  • Decision Making*
  • Electromyography
  • Feedback, Psychological*
  • Female
  • Humans
  • Male
  • Motion Perception*
  • Psychomotor Performance*
  • Reaction Time*
  • Time Perception*
  • Volition*
  • Young Adult