The persistence of memory: contiguity effects across hundreds of seconds

A contiguity effect-the finding that stimuli that occur close together in time become associated to each other--is observed between words that are separated by several seconds. The traditional account of contiguity effects is that item representations become associated to each other while active in a short-term memory buffer--a limited-capacity store that can hold a small, integral number of items. Participants studied and free recalled 48 lists of words. At the end of the session, participants were given a surprise final free recall test on all of the items from all of the lists. In addition to a standard contiguity effect between items presented at nearby serial positions, we simultaneously observed a contiguity effect between items presented in different lists. This latter contiguity effect extended over several lists, or several hundred seconds, well beyond the range that can be attributed to a buffer holding a small, integral number of items.