List Memory

[Troy Kelley]

To:   Troy Kelley <tkelley at arl.army.mil>
cc:
Subject:  Re: List Memory
 
 
>Anyone out there know of any research that pertains to the difficulty of
>remembering a series of unrelated items.  For example, how much harder is
>it to recall one item vs three?  Is it just a straight probability?.. you
>have a 1/3 chance of remembering one item out of three, and that you have
a
>1/1 chance of remembering just one?   I would like to incorporate
>activation levels into the formula.  So, If they were related items, my
>activation levels (through spreading activation) takes that into accout,
so
>perhaps I can use the same formula as long as I use activation levels?
For
>example, suppose I have 3 items with activation levels of .3, .4 and .1..
>how much harder is it to remember that than one item with an activation
>level of .2?
 
-The short answer is that the probability of retrieving a series of
-unrelated items is a non-linear function that can depend on a number of
-experimental factors and a number of effects such as recency and primacy.
-But chapter 7 has some formulas resulting from the activation calculus
that
-are fairly simple but do a good job of approximating reality.
 
-As for your last question, i.e. the probability of remembering items as a
-function of their activation, it is given directly by the Retrieval
-Probability Equation (3.7 p. 74) and the Chunk Choice Equation (3.9 p.
77).
-Those equations will be unified in ACT-R 5.0 but they have to do for now.
 
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