Second-order control of sequence-class equivalences in children.

Children learned matching-to-sample tasks to establish two equivalence classes. Then, one member from each class appeared in a sequence procedure, thereby acquiring the ordinal properties "first" and "second". When the remaining members in the two equivalence classes were placed in the sequence context, subjects responded in appropriate order without additional training. The data suggest a basic mechanism which can account for the production of new sequence behavior which has no explicit history of training.