Many of the assumptions in the model are contentious but Anderson and his group and a growing number of researchers in Europe make a serious effort to support the assumptions by empirical research or replace them by other assumptions when they are falsified. About 11 of the 32 papers used the ACT-R model as their basis. This is because it is the most elaborate computational model of human cognition and because an implemented version is freely available. Most papers concerned extensions of ACT-R, in particular to visual perception. For example, a cognitive model of a reasoning process must make explicit assumptions about perception in the task and also about learning.
People learn many things without being aware of it.
In many experiments people even deny that they have learned anything although their behaviour proves that they did. The presentation that I found most impressive was by Deb Roy from MIT MediaLab. He constructed a system with a visual and sound sensors. The system takes as input parallel visual and sound streams. The goal is to model perceptual learning in infants and the input to the system were visual and sound recordings from an infant playing with objects with its mother.