Behavioral and Brain Sciences

Open Peer Commentary
Halford et al.: Relational complexity

ACT-R: A higher-level account of processing capacity

John R. Anderson a1, Christian Lebiere a1, Marsha Lovett a1 and Lynne Reder a1
a1 Psychology Department, Carnegie Mellon University, Pittsburgh, PA 15213


We present an account of processing capacity in the ACT-R theory. At the symbolic level, the number of chunks in the current goal provides a measure of relational complexity. At the subsymbolic level, limits on spreading activation, measured by the attentional parameter W, provide a theory of processing capacity, which has been applied to performance, learning, and individual differences data.