January 6 2012

Consciousness

What does it mean to be conscious? Silly question, right? We all know what it means–at least I do but how do I know about you? And how can I be sure about me? Therein lie a million questions.
Luckily, there is an increasing tide of research that is looking into what is really going on with the phenomena that we call consciousness. I think I’ll do a few posts on this through the year as it is a subject that really interests me. We’ll start with a very interesting experiment performed by BENJAMIN LIBET, CURTIS A. GLEASON, ELWOOD W. WRIGHT and DENNIS K. PEARL in the early 80’s and presented in a paper called “Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential). The unconscious initiation of a freely voluntary act.” in Brain, 106:623-642.

The experiment is:
Electrodes are placed on a subjects scalp and hooked to an EEG to measure cortical neuronal responses.
Electrodes are also placed on the skin over the activated muscle of the forearm. The timing of this is measured with an EMG.
An oscilloscope whose face displays a dot moving in a circle with marks is shown to the subject.
The subject is asked to perform a task like pressing a button. The subject is also asked to note the position of the dot upon the oscilloscope when they first became aware of the intention to press the button (for example).
The actual time of the button press is recorded electronically and the position of the dot is also recorded at the same time.
On average it was found that about 200 milliseconds elapsed between when the subject claimed intention to when the button was pushed. Of even more interest was that approximately 500 milliseconds before the button was pushed, the EEG would record mounting neuronal activity. In other words, prior to “you” deciding to push the button, subconscious processes have already made the “decision” and the “you” in the process is just along for the ride as an observer.
I’d say that qualifies as pretty interesting.



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Posted January 6, 2012 by user in category "Interesting stuff

2 COMMENTS :

  1. By EEGiorgi on

    Did you read this? Quoted from Peter Watts: “when you split the brain down the middle — force the hemispheres to talk the long way around, via the lower brain, instead of using the fat high-bandwidth pipe of the corpus callosum — you end up with not one conscious entity but two, and those two entities develop different tastes, opinions, even different religious beliefs.”

    I had NO idea — how cool is that?

    Reply

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