Archive for August, 2007

August 10, 2007: 4:37 pm: ACT-R/S, Cognitive Modeling, Spatial Reasoning

Have I mentioned how much I hate modeling dual-tasking? I will concede that using Dario & Niels’s threaded cognition does make things significantly easier – but it is still a royal PIA.

The initial stab at the dual-tasking model (spatial/verbal 1-back and pointing), was ok, but at some point between getting it working and running it at ICCM, something stopped working. Regardless, though, the model wasn’t quite what I was aiming for. The majority of the errors were timeouts, with very few errors.

The new one, is looking much better with spatial interference from other representations (without jacking up the base level noise) – but still not ideal. The threaded cognition, while a step in the right direction, depends upon a very simple but problematic assumption: buffers being empty. The idea is that any goal thread will block while the buffer it needs is occupied. If you follow this, you can get some decent interleaving. However, that kills how many productions work. Often times, chains of productions depend upon a chunk in the retrieval/imaginal/visual buffer.

It’s not such a challenge to harvest and reinstate these bits of information, but it is if the buffer has a capacity greater than one (the configural buffer). I’m relying on the pointing and 1-back to interfere with each other at the buffer level (stepping all over each other), which means I can’t depend on the buffer being empty as a semaphore. It’s an interesting balancing act. My solution for now is to have more productions that test for the occurrence of interference (i.e. buffer is empty but shouldn’t be or the wrong chunk is in the buffer) – which has a nice benefit that I can actually keep track of where the interference is occuring precisely.

The models are running now, we’ll see. One thing that I definitely cannot account for yet is why there are more errors in verbal 1-back & rotate than stationary. There’s just no clear theoretical position from ACT-R’s perspective. meh.

August 9, 2007: 8:40 pm: Publications, Spatial Reasoning

Harrison, A.M. (2007) Reversal of the Alignment Effect: Influence of Visualization and Spatial Set Size. 29th Cognitive science society conference. (Paper)

: 8:37 pm: ACT-R/S, Cognitive Modeling, Publications, Spatial Reasoning

Harrison, A.M. (2007) The Influence of Spatial Working Memory Constraints on Spatial Updating. 8th International Conference on Cognitive Modeling. Doctoral consortium. (Paper)

August 4, 2007: 9:56 am: Awards