Analysis of a choice-reaction task yields a new interpretation of Libet's experiments.
Benjamin Libet has demonstrated that the readiness potential precedes the time at which participants consciously decide to perform an intentional motor act, and suggested that free will is an illusion. We performed an experiment where participants observed a stimulus on a computer monitor and were instructed to press one of two buttons, depending on the presented stimulus. We found neural activity preceding the motor response, similar to Libet's experiments. However, this activity was already present prior to stimulus presentation, and thus before participants could decide which button to press. Therefore, we argue that this activity does not specifically determine behaviour. Instead, it may reflect a general expectation. This interpretation would not interfere with the notion of free will.
Herrmann
Christoph S
CS
Otto-von-Guericke-University, Department for Biological Psychology, Magdeburg, Germany. Christoph.Hermann@nat.uni-magdeburg.de
Pauen
Michael
M
Min
Byoung-Kyong
BK
Busch
Niko A
NA
Rieger
Jochem W
JW
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D002755:Choice Behavior / Q000502:physiology; D003265:Contingent Negative Variation / Q000502:physiology*; D003627:Data Interpretation, Statistical; D004585:Electrooculography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D014836:Volition