Benjamin Libet - Libet's short delay.
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Saved by 2 people (0 private), first by anonymouse user on 2009-03-17
- Rgarns on 2009-03-17 - Tags freewill , Libet , consciousness , mind , neuroethics , cogsci
- Monacojerry on 2006-09-14 - Tags philosophy
Public Sticky notes
whatever the voltage or frequency of the
pulses, the stimulus had to persist for about 500 milliseconds before the
subject became consciously aware of it.
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But we also respond to
events, and here a delay is highly relevant and noticeable.
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our unconscious responses are far quicker than
our conscious ones
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Libet's hypothesis was that conscious awareness is
subjectively referred backwards in time. We consciously perceive the
stimulus as occuring at the same
moment it registers unconsciously, even though it doesn't in fact enter our awareness
until it has persisted for half a second. Subjectively we backdate it to match
the EP at the beginning rather than the end of the 500
millisecond span.
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Perhaps the
sensations actually enter conscious awareness immediately, and the
half-second delay merely allows time for them to become reportable, or
fixed in short term memory? Perhaps we are merely dealing with the
difference between being aware of the stimulus, and being aware that we
are aware of it? Libet contends that awareness and memory, especially
declarative, explicit memory, are different and independent
phenomena.
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the perceived time at
which we make a decision must also be subjectively referred back by 500
milliseconds. Unlikely as it seems, and contrary to our own impression, we
must have made our decisions slightly before we actually become aware of
them.
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This 'Readiness Potential' or
RP appeared about 800 milliseconds in advance of the act, and seemed to be
a clear indication that the intention to act had formed.
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the RP appeared some 500 milliseconds before the reported
awareness of a decision to move
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free will was a delusion
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Although the subject's decision to move occurred too early for it
to have been initiated by conscious thought, there was still - just - a
window of opportunity in which conscious awareness might conceivably veto
the move.
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Is the RP really a signal
that a decision has been made?
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Might not the RP merely signal a
quickening of attention, rather than a moment of decision?
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isn't it possible that we need a certain amount of
time just in order to report the awareness to
ourselves?
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his proposed CMF is an emergent phenomenon: something that arises from
the combination of active neurons but amounts to something distinctively
more than, and different from, the sum of brain activity.
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