There is ample evidence that people cannot generate random series when
instructed to do so. Rather, they produce sequences with too few symm
etries and long runs and too many alternations among events. The autho
rs propose a psychological theory to account for these findings, which
assumes that subjects generate nonrandom sequences that locally repre
sent theoretical random series subject to a constraint on their short-
term memory. Closed-form expressions are then derived for the major st
atistics that have been used to test for deviations from randomness. R
esults from 3 experiments with 2 and 3 equiprobable alternatives suppo
rt the model on both the individual and group levels.