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Dear list,
An excellent question which summarizes some of my research goals and
interests.
There certainly seems to be a lack of studies in auditory perceptual
learning. Some of the earliest studies that I can think of are Massaro
et al. on learning in backward masking (Perception and Psychophysics
circa 1979?). More recently, Beverly Wright and colleagues (J.
Neuroscience, 1999) published results on auditory temporal interval
discrimination learning. She has also presented posters at ARO on
learning of frequency discrimination, backward masking, and
interaural-interval discrimination.
It seems that most of these tasks are subject to some sort of learning
effects. The characteristics of that learning are probably task
specific. It appears that the learning is dependent on a heavy schedule
of at least 900 trials a day and has both a fast and slow time course.
The fast time course seems to take 1-2 sessions and the slower time
course about 5-8 sessions. This is consistent with time courses of
learning in both visual and somatosensory systems as well.
To my knowledge, no one has done anything like the Karni or Strickgold
et al. manipulations of REM sleep etc. with auditory perceptual
learning.
I think that one reason learning has been ignored is that it just seems
to make everyone asymptote to a similar threshold. i.e. high-threshold
beginners learn a lot more than low-threshold performers. So, the
process might look something like a regression to the mean. While that
may indeed be the case, I believe that the characteristics of
generalization to untrained stimulus conditions following learning are
quite revealing about the mechanisms of processing and learning.
Typically learning studies are done with naive subjects.
I would be delighted to hear other comments on this topic from the more
experienced folks in the list.
Srikantan Nagarajan
Assistant Professor
Department of Bioengineering
University of Utah, Salt Lake City
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