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Minimum exposure time?

Michael Hucka hucka at eecs.umich.edu
Fri Dec 9 02:50:08 EST 1994


>>>>> On 8 Dec 1994, izumi at pinoko.berkeley.edu (Izumi Ohzawa) wrote:

  izumi> I don't believe there is any lower limit to exposure duration as
  izumi> long as you maintain the energy of the stimulus constant (# of
  izumi> photons delivered).  If a person can see it with 10-20 msec
  izumi> exposure, you should be able to deliver the image with the same
  izumi> energy within 1 msec or even 10 microsec and have practically the
  izumi> same effect.

  izumi> All experiments you quoted have the problem of proportionally
  izumi> smaller stimulus energy as the duration is reduced.  Therefore, the
  izumi> lower limit reported may simply be due to threshold for stimulus
  izumi> strength rather than that of exposure duration.

Perhaps I misunderstand something, but it seems like there are two issues
here.  One is the question of stimulus strength (say, in terms of photons
delivered), but another is what happens when one stimulus is followed by a
different pattern.  In an experiment involving the presentation of a stimulus
followed by a pattern mask, doesn't the mask disrupt processing of the first
stimulus?  No matter how much stimulus energy is presented in the first
stimulus, the brain is only going to have the input pattern for a finite
period of time before the mask appears.  So I guess my original question
was not very clear; I meant to ask about the amount of time allowable between
patterns.
--
   Mike Hucka (michael.hucka at umich.edu)
   University of Michigan, Ann Arbor, Mich.



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