Question on a specific difference between ACT* and ACT-R

[Lionel Marquis]

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

Bフiment GＰpolis 4779

Tï¼­: +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