Some data suggest that, as in explicit serial learning, longer sequenc
es are more difficult to learn implicitly. These findings have been us
ed to support the inference that implicit learning is capacity-limited
. However, investigations of the effect of sequence length on implicit
learning have confounded sequence structure with sequence length. The
se factors were manipulated independently in 3 experiments using a ser
ial reaction time task. The results showed that sequence structure, no
t sequence length, largely determines the extent of sequence learning.