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

[Kevin.Gluck at williams.af.mil]

Dan recently mentioned that a "unified" state mechanism is under
consideration for ACT-R 6.  Perhaps a unified spreading activation mechanism
for the buffers would be worth considering, as well.  

-----Original Message-----
From: Stefani Nellen [mailto:Stefani.Nellen at urz.uni-heidelberg.de]
Sent: Monday, December 02, 2002 11:34 AM
To: Jerry.Ball at williams.af.mil
Cc: act-r-users+ at andrew.cmu.edu
Subject: Re: [ACT-R-users] Spreading Activation and Retrieval Chunks

> 
> Of course, this begs the question -- is the chunk in the retrieval buffer
in
> the focus of attention?
> 
> Jerry
> 
Even more so than the goal chunk, I would say- one could think of the
chunk in the retrieval buffer as one potential focus of the current
attention (along with the contents in the perceptual buffers), while the
chunk in the goal buffer could be thought of as more remote, more
abstract- something that provides guidance for the current thinking and
behavior, perhaps even on a metacogntive level. But perhaps this is
overloading architectural components with meaning?

Steffi
> -----Original Message-----
> From: Frank E. Ritter [mailto:ritter at ist.psu.edu]
> Sent: Friday, November 29, 2002 9:37 AM
> To: Jerry.Ball at williams.af.mil; act-r-users+ at andrew.cmu.edu
> Subject: Re: [ACT-R-users] Spreading Activation and Retrieval Chunks
> 
> At 15:24 -0700 27/11/02, Jerry.Ball at williams.af.mil wrote:
> >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.
> 
> couldn't you make the retrieval chunk part of the goal chunk, and get
> some, albeit, a lighter activation propogation?
> 
> Cheers,
> 
> Frank
> 
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-- 
Stefani Nellen

Hans-Thoma-Str. 72
69121 Heidelberg
Tel.: +49-(0)6221-373510

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