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 [email protected] [email protected] [email protected] [email protected]


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.