The moment of decision 1

There is a new Research Report by WP Banks and EA Isham, ‘We Infer Rather than Perceive the Moment We Decided to Act’ (here). I am going to divide looking at this paper in two: first is what they have to say about previous research and then what they report on their experiments.

“The question of free will has been debated since antiquity. The debate has traditionally been conducted only in theoretical or logical terms, but has recently been given empirical content by the research of Libet, Gleason, Wright, and Pearl (1983). They made the question of volition a neurophysiological one, and thus opened it to scientific investigation.

Kornhuber and Deecke (1965) found that a simple voluntary act such as pressing a key was preceded by an electroencephalographic (EEG) component known as the “readiness potential” (RP) that began 500 ms to about 1,000 ms before the action. Libet et al. (1983) asked participants to monitor a spot of light moving around a clock face and to report the location of the spot when the action was consciously initiated. The reported time, termed W, was approximately 200 ms before the response. This time of decision implies that neurological preparation for the action began about 300 to 800 ms before the person consciously made the decision to act. Conscious will would thus seem to be a latecomer in the process of choice, rather than the instigator of choice.

When a simple measurement challenges bedrock intuitions about free will, it is no surprise that it would be challenged.”


These criticisms have been answered by Banks, Pockett, Miller and Haggard and it appears that Libet’s clock method are viable for timing the awareness of decisions.  As the reported time when action was consciously initiated (W) is not an artifact of experimental apparatus or procedure.

“…what does it mean? Researchers have reasonably searched for a cluster of neural events corresponding to W among those generating the RP.”


In the second post, I look at a different theory investigated by Banks and Islam.

One thought on “The moment of decision 1

  1. Derivatives of the EEG technique include evoked potentials (EP), which involves averaging the EEG activity time-locked to the presentation of a stimulus of some sort (visual, somatosensory, or auditory). Event-related potentials (ERPs) refer to averaged EEG responses that are time-locked to more complex processing of stimuli;`”^*

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