Ok, I know.. I should have had a release out the door last week, but the out-of-order communication bug took longer to resolve than I'd thought. It's done now, so I've been working on some of the compatibility issues. Indexed retrievals are now disabled by default, but can be reinstated if you'd like. Movement tolerance in the visual system is up next along with object tracking.

Retrieval module

Indexed Retrievals

Retrieval module does permit indexed (i.e. immediate) retrievals of chunks you already have references to. However, this must be explicitly enabled with the EnableIndexedRetrievals parameter.


Retrievals can also be performed asynchronously if the declarative module is asynchronous.


Here I list out the general differences between the canonical and the Java implementations of ACT-R. Since jACT-R has been coded largely in isolation from the canonical code, there are many design decision differences.

Version 6

The default implementation provides access to the basic retrieval functionality, as well as exposes the parameters defined in 4.0 (LatencyFactor,LatencyExponent) and permits partial matching (if the declarative module's PartialMatchingEnabled is true).


The basic retrieval module template. All retrieval module implementations must support the parameter RetrievalThreshold, which defines the minimum chunk activation value that a chunk must have to be accessible.


This past month has seen a significant push to meet a demo deadline. During the course of the push, one of my coworkers at NRL kept correcting some mistakes in jACT-R. Many of them are not actually mistakes, but different implementation decisions. In those cases where its a definite bug, they are being corrected. Those that are just implementation differences, where it will make a big difference for lisp modelers, I will make the behavior parameterized and default that parameter to be consistent with the lisp.


Theoretical functionality in jACT-R is defined and extended through the use of modules. As modules are developed and refined, their specification and details will be added here.

Why, why, why?

Ok, sometimes I get questions such as "why did you sacrifice at least a full year of your graduate career to reimplementing a perfectly good system?" (actually, I'm paraphrasing because the actual questions typically question my sanity). Anyway...

New Release (

It's been a little while, but that doesn't mean things haven't been progressing. Lots of new features, lots of improvements, and the usual slew of bug fixes.

Note worthy:

Some help for folks not familiar with Eclipse

Here's a great intro to using the Eclipse workbench for those not already familiar with it.


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