[Neuroscience] Re: Brain and awarness

feedbackdroids at yahoo.com feedbackdroids at yahoo.com
Thu Mar 30 12:52:48 EST 2006


tehgabriel at web.de wrote:
> Hi!
> The average reaction time of humans is around 1 s (e.g. time one needs
> to initiate braking his car after the perception of a red light).
> Training and expectation (you know that a certain event will happen)
> can lower the reaction time to 0.1 to 0.4 s. So, definitivley below 0.5
> s.
>
> Concerning your example with the pitcher (I am not familiar with
> baseball) i would assume what enables one to hit the ball properly is
> the ability to predict a chain of subsequent events. One can predict
> (note that precision of prediction increases with experience/practise):
> how the pitcher will move  =>  at which point the ball will leave his
> hand  =>  the way of the ball
>
> Regards,
> Thomas
>


This is exactly correct. Nothing in cognition [ala brain operation]
simply starts and stops at specific times. Rather all operations are
performed in the context of "on-going" foreground and background
activity. In the end, I think, people will come to realize that this is
the key issue involved in the correct interpretation of Libet's
experiments, too.

Eg, if you look at the P300 alerting wave, it doesn't simply exist at
one point in time, with a clearcut beginning and end. Rather, it builds
up steadily over a 100-200 msec time span, and than wanes over an
additional 500-800 msec. It just happens to "peak" at about 300 msec.
What this indicates is that neural activity persists in internal neural
feedback loops for much longer than simple 1-to-1 transmission between
neurons, which will take only 10-20 msec. For activity to last upwards
to 800-msec, it must involve multiple passes around the internal loops,
while first more and then less neural tissue is being recruited into
the process.

All of this internal activity is taking place within the brain during
any cognitive or behavioral task. This is continually performed
internally while the external events are taking place. As the pitcher
gets ready to throw, winds up, stretches, and then releases the ball,
all of these external activities are reflected by internal brain
operations in the batter in preparation to hit the ball. Each step
involves updating internal predictions of where the ball will go.
Without these internal predictions, the batter couldn't possibly hit
the ball. Every nuance of the pitcher's activity will change the
internal predictions in some way, before the pitch. After the ball is
pitched, its trajectory will further modify the internal predictions,
and the movement of the muscles to hit the ball. Finally, batters can
modify the bat trajectories even as they swing, based upon where they
predict the ball will be going as the flight ensues.

The best pitchers either throw the ball so fast that the batter's
predictive [and probably motor] machinery cannot keep up, or else are
able to throw balls with so much spin that the balls suddenly change
course too late for the batters to be able to respond. Eg, balls that
come relatively straight but then suddenly sink over the plate at the
last instant, as the spin effects build up. Spin effects are pretty
cool. When I bowled the 3 or 4 times I ever bowled, I had a wicked hook
on the ball. It would fly down the edge of the lane, first relatively
straight due to forward momentum, and then at the last instant curve
around and into the pins, and spin took over from forward momentum.
Neat.

For a 100 MPH pitch [the fastest recorded], and 90' to the plate, it
only takes about 0.6 sec for the ball to travel the distance, so
without an entire spectrum of one-after-another perceptual cues and
especially internal predictive mechanisms, the batter could never ever
hit the ball.



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