Frank Wilczek’s book: Fundamentals – Ten Keys to Reality

 I just started this book.

Frank Wilczek is a Nobel Laureate in Physics.

Here is an excerpt from the preface.

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Psychophysics reveals that consciousness does not direct most actions, but instead processes reports of them, from unconscious units that do the work.  Using a technique known as transcranial magnetic stimulation (TMS), it is possible to stimulate the left or right brain motor centers in a subject's brain, at the experimenter's discretion.  A properly sculpted TMS signal to the right motor center will cause a twitch of the left wrist, while a properly sculpted TMS signal to the left motor center will cause a twitch of the right wrist.  Alvaro Pascual-Leone used this technique ingeniously in a simple experiment that has profound implications.  He asked subjects, upon receiving a cue, to decide whether they wanted to twitch their right or their left wrist.  Then they were instructed to act out their intention upon receiving an additional cue.  The subjects were in a brain scanner, so the experimenter could watch their motor areas preparing the twitch.  If the had decided to twitch their right wrist, their left motor area was active; if they decided to twitch their left wrist, their right motor area was active.  It was possible, in this way , to predict what choice had been made before any motion occurred.

Now comes a revealing twist.  Occasionally Pascual-Leone would apply a TMS signal to contradict (and, it turns out, override) the subject's choice. The subject's twitch would then be the one that TMS imposed, rather than the one he or she originally chose.  The remarkable thing is how the subjects explained what had happened.  The did not report that some external force had possessed them.  Rather, they said, "II changed my mind".