What is a "hybrid" model?

[Steve Kemp]

On Thu, 4 Apr 1996, Terry Dartnall wrote:

> 
> Thanks for that useful overview.  You say
> 
> >The sudden learning was demonstrated in studies of human problem solving
> > where it was eventually dubbed the "Aha!" effect.  (I believe that there
> >is a book by that name, but I don't have that reference.)  In animal
> >learning, it is known as one-trial learning.
> 
> I know pretty much nothing about the area, but I would have thought that
> one-trial learning and the "Aha!" effect were different.  I learnt not to
> stick my fingers in a power socket when I was a kid - and it only needed one
> trial! - but I wouldn't have though this was an "Aha!" situation. (It was a
> "Yow!" situation.)  This applies to animals other than people, I'm sure. 
>
A good point.  The original post was contrasting the sudden learning 
found with the Aha! effect with what the poster called "gradual" 
learning.  If the distinction (that makes for the two types) is between 
gradual and sudden learning, then one-trial learning, while perhaps 
distinct from insight learning, seems to be sudden rather than gradual.  
That is, there are other non-gradual types of learning besides insight 
learning.

>                                                                          And
> you can have the "Aha!" effect after many trials, as with Koehler's apes. In
> fact I would have thought this is when you usually get it - after lots of
> frustrating failures.  So one-trial learning is neither necessary nor
> sufficient for the "Aha!" effect.
> 
> Isn't the "sudden learning problem" that, after a number of unsuccessful
> trials or trials, the answer suddenly comes to us?
> 
Another way of looking at it is that if insight learning occurs on the
very first trial, it is very hard to distinguish such a case from
one-trial learning, at least from an empirical perspective.  The banana
problem was quite a challenge for the mental capacity of the apes
involved.  The power socket "problem" was quite easy for you.  If we were
to suppose that certain types of learning *are* sudden, then doesn't it
make sense that the sudden onset of learning would occur on an early trial
for "simple" or "easy" problems and on a later trial for more "complex" or
"harder" problems?  In that case, the Aha! effect would just be the 
natural result of being presented with a difficult problem.

In fact, in the mathematical learning theory literature, a number of
Markov-based models were constructed after just such an assumption.  It
was assumed that all learning was "all-or-none" in character.  Apparent
gradual change was modeled as "random" correct guessing by subjects who
had not yet "learned," plus artifacts of emprical measures used by
experimenters that averaged across subjects or trials where learning had
occurred in some instances and not in others. A remarkably large number of
learning phenomena, including many apparently gradual ones, were
successfully modeled. 

Finally, "sudden" or "gradual" is measured with respect to the number of 
trials.  It is essential to Kohler's conception that some sort of ongoing 
internal "contemplative" process was occurring all through the process, 
during and between trials.  More trials more rapidly presented allow a 
gradual process to appear gradual.  If the subject is gradually catching 
on and we present fewer trials less often, then the gradual learning may 
appear sudden because enough learning occurred in the long interval 
between trials to become noticeable all at once on the following trial.

In sum, my point is that it is difficult, if not impossible, to establish 
the existence or non-existence of genuinely different *types* of learning 
solely from behavioral phenomena, however augmented by theory or 
mathematics.  One of the truly exciting things about the recent advances 
in the various technologies of brain monitoring is that they provide a 
second type of empirical evidence that can be correlated with behavioral 
evidence to discover if apparently distinct learning phenomena involve 
genuinely different brain mechanisms.

regards, steve K

Steven M. Kemp                |
Department of Psychology      | email:  steve_kemp at unc.edu
Davie Hall, CB# 3270          |
University of North Carolina  |
Chapel Hill, NC 27599-3270    |   fax: (919) 962-2537