[ACT-R-users] Question on a specific difference between ACT* and ACT-R

[lionel.marquis at unil.ch]

Hi,

I have only basic level in ACT-R or similar models of memory 
functioning. The aspect I am most interested in is the "spreading 
activation" part of ACT-R.

Here is my question. In earlier versions of the model (i.e., ACT*) 
there was a parameter p to account for the fact that "the total 
activation emitted by a node is less than its own activation, that is, 
if ai is the activation of node i, it sends p*ai units of activation 
to all connected nodes where p<1. Because of this factor, the amount 
of activation decreases exponentially with distance from source" 
(Anderson & Pirolli 1974: 794).

In later versions (i.e., ACT-R), this parameter p had dropped from the 
equations. What are the (theoretical or empirical) reasons for 
removing p? Or is the idea behind factor p somehow still accounted 
for, but in a different form?

Thanks a lot in advance for your help on this particular point !

Best regards,
Lionel Marquis



==================================
Lionel Marquis
Institut d'Etudes Politiques et Internationales
University of Lausanne
Switzerland
Bâtiment Géopolis 4779
Tél: +41 21 692 31 56
Fax: +41 21 692 31 45
E-mail: Lionel.Marquis at unil.ch
Web: http://www.unil.ch/iepi/page14150.html





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