List Memory

[Wolfgang Schoppek]

> I guess I wasn't quite clear as I should have been.  Given that ACT-R has
> taken care of the effects of recency and primacy and incorporated those
> effects into activation levels, then how hard would it be to do each
> retrieval assuming that each activation level is above the necessary
> threshold.  Are all retrievals equally as likely assuming that each chunk
> is above the necessary threshold?  Or should you incorporated a probability
> estimate for each group of retrievals (probability of 3 items is .33,
> probability of 2 items is .5).  For example, suppose you had to recall X &
> Y, and X & Y had certain activation levels associated with each.  Now
> suppose you had to remember Z, how much easier is it to remember Z, where Z
> has a given activation level as well, and Z is unrelated to X or Y?  Let's
> say that the activation level of X is .26 and Y is .31 and Z is .25, so is
> it still easier to remember Z, just because there is only one retrieval
> involved? or are both groups equally as "easy" simply because each one has
> an activation level above a given threshold?
>
> Troy
 
I guess the key to solving that confusion is that you must not "assume"
activation levels. They are not arbitrary values but the result of the
mechanisms of ACT-R that come into play depending on your specific model (e.g.,il
,
rehearsing less items in the same amount of time will return a higher baseleve
l
for each item). Once you have the activation levels determined by the model,
the equations mentioned by Christian will give you estimates about probability
 
of retrieval.
 
Wolfgang