[ACT-R-users] Baseline activation strengthening and decay

[Hongbin Wang]

Ben,

I assume you were entertaining some interesting scenarios when you  
raise these questions. A lot of processes can happen when one  
maintains the eye fixation at an object or a few objects for a while.  
For example, during the fixation, presumably, 1) one can get shocked  
and one's mind goes blank (eg, seeing a dead man walking); 2) one can  
engage in one single retrieval for a long time until tired (eg,  
trying to recollect who that familiar face belongs to); or 3) one can  
engage in a chain of retrievals (eg, that face looks similar to  
Johnson's, Johnson cried yesterday because his dog died, oh, what a  
dog...). That's one reason why ACT-R has a modular design, so  
different modules can do different things in parallel (with  
constraints, of course).

I believe trying to figure out what happens during your expert's  
1500ms fixation is one reason why we do modeling. We can speculate  
what's going on based on his next eye-fixation, his verbal protocol,  
his decision and action, etc. When we have a better understanding of  
the process, we can simulate, predict and test its implications on  
baseline activation learning. Sometimes even if one is staring at a  
target (via the visuospatial module), but his mind may be attending  
to or working on something else (via other modules). In this case, I  
doubt the time length of fixation would strengthen the activation  
level of the target.

Hongbin


On Feb 15, 2006, at 9:30 PM, <ben.willems at faa.gov>  
<ben.willems at faa.gov> wrote:

>
> Please excuse my ignorance, but I am working on the other side of  
> the cognitive modelers.  That is, I run simulations using human  
> experts in Air Traffic Control and create records of human activity  
> quite similar to what you call a simulation trace.  Ignoring for a  
> moment that the visual system may be able to process several things  
> within the foveal area simultaneously, how would you interpret a  
> single 1500msec fixation on an object in terms of number of  
> retrievals?  Does that include a single retrieval or does it  
> involve cyclic retrievals with a time constant of 50msec for the  
> retrieval and another 50msec to push the chunk to the goal stack?   
> Or do you assume that initially there is a retrieval followed by  
> maintaining activation at a faster cycle time?  Do you assume that  
> activation strengthening occurs independent of the perceptual or  
> motor event that triggers activation of the chunk?  E.g., seeing an  
> aircraft representation vs. listening to a reference to an aircraft  
> or typing in an identifier for that aircraft.
>
> Ben Willems
> Engineering Research Psychologist
> William J. Hughes Technical Center
> NAS Human Factors Group (ACB-220)
> Building 28
> Atlantic City International Airport, NJ 08405
> USA
> Phone:  609-485-4191
> Fax:  609-485-6218
> E-mail: Ben.Willems at faa.gov
> _______________________________________________
> ACT-R-users mailing list
> ACT-R-users at act-r.psy.cmu.edu
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-------------------------
Hongbin Wang, PhD
Assistant Professor
School of Health Information Sciences
University of Texas Health Science Center at Houston
7000 Fannin, Suite 600, Houston, TX 77030, USA
Hongbin.Wang at uth.tmc.edu, Tel: 713-500-3911, Fax: 713-500-3929

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