[Neuroscience] Re: Brain and awarness
Glen M. Sizemore
gmsizemore2 at yahoo.com
Thu Mar 30 13:49:18 EST 2006
Ohhhhh! I see. We couldn't just say that the person responds, in part, to
the pitcher's motion. A copy of the pitcher's motion has to get inside the
brain where the homunculus can see it. Right Dan?
<feedbackdroids at yahoo.com> wrote in message
news:1143741168.024219.135950 at e56g2000cwe.googlegroups.com...
> tehgabriel at web.de wrote:
>> 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
>> 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
> 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.
> 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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