[ACT-R-users] Spreading Activation and Retrieval Chunks

[Jerry.Ball at williams.af.mil]

In ACT-R 5.0, only the goal chunk spreads activation to declarative memory.
This means that before a chunk can spread activation, it must become the
goal chunk.  Thus, if a model retrieves a chunk from declarative memory and
wants to retrieve chunks associated with the retrieved chunk, the retrieved
chunk must first become the goal chunk.  This makes it difficult to create a
model that follows associative links without putting the goal of following
the associative links into the declarative chunks themselves. 

Given that fact that activation in ACT-R 5.0 only spreads to directly
related chunks (i.e. there is no propagation beyond directly related
chunks), allowing activation to spread from the retrieval chunk as well as
the goal chunk would provide a secondary mechanism for spreading activation
and would eliminate the serial bottleneck of having to push retrieval chunks
into the goal buffer (which takes at least 1 production just to shuffle
chunks around) to follow associative links.

Jerry