Self and Free Will 251“9x6” b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanitygrade to pass the exam, that he has to know chapter 4 well, that he
has to locate page 65 where chapter 4 is, and that he has to twist his
right thumb along with the index finger to turn the pages. Which of
this series of intentions is the cause of the action — turning the book
to page 65? The proximate cause is the motion of the fingers, but this
is only a minor part of a long series of goal-directed activities (see
diagram in Fig. 11.2). Some of the intentions are remote, some are
intermediate, while some are immediate (muscle movement). Libet
and Wegner’s interpretation^20 of intention and free will based on readi-
ness potential could be far too narrow. Although a common endpoint
of all volition, voluntary muscle contraction is just a part of the activity
resulting from free will.^21 It has been suggested that in Libet’s exper-
iment, the effective intention might have started when the subjects
agreed to participate in the experiment, long before the twitching of
a muscle.^22
Besides, Libet himself suggested that the agent could abort the
action after feeling the urge to act, questioning readiness potential as
the irreversible cause of an action.^23 This “veto power” that overrides the
readiness potential signifies the ability of the brain to suppress an initial
impulse and has been interpreted by some to be a free choice — or the
“real” free will. A brain area called the dorsomedial prefrontal cortex has
been found to be activated during this inhibitory function.^24
In short, although the exact timing of volition is currently mired in
controversy, the idea that the subjective sense of agency of an act derives
from the matching of the feed-forward and feedback messages in the
brain remains a plausible hypothesis (Fig. 11.3).
11.10 Pathological States of Volition
Alien hand syndrome refers to involuntary, complex motor behavior
observed in patients with damage in the premotor and supplementary
motor areas, leaving an intact primary motor cortex. The hand does not
obey the command of the agent, as if it had “a will of its own.” The hand
can engage in mischievous behavior against other parts of the body, such