Instability in memory phenomena: a common puzzle and a unifying explanation.

In mixed lists, stable free recall advantages are observed for encoding conditions that are unusual, bizarre, or attract extensive individual item elaboration relative to more common encoding conditions; but this recall advantage is often eliminated or reversed in pure lists. We attempt to explain this ubiquitous memory puzzle with an item-order account that assumes that (1) free recall of unrelated lists depends on order and item information; (2) unusual items attract greater individual item-processing but disrupt order encoding regardless of list composition; and (3) list composition determines differences in order encoding across unusual and common items. We show that the item-order account provides a unifying explanation of five memory phenomena for which the requisite data exist. The account also successfully anticipates pure-list reversals, in which the standard mixed-list recall pattern is obtained in pure, structured lists, a finding that competing accounts cannot handle. Extending the item-order account to other "established" recall phenomena may prove fruitful.