Studies of social memory support the trite adage, "Two heads are better than one." But there is more to this story. When recalling meaningful materials such as stories, word lists, and criminal acts, groups remember more than individuals. But in the recall of meaningless materials such as nonsense syllables, group and individual recall do not differ. However, even with meaningful materials, collaborative memory typically falls short of performance predicted by combining individual output (Clark and Stephenson, 1989). To determine if social interaction influences group recall, students of social memory have turned to comparisons between collaborative and nominal groups (see Figure 1).

Collaboration in Recall

In 1997, Weldon and Bellinger advocated testing nominal groups. In nominal groups participants actually recall separately, and the sum of their nonoverlapping output is calculated. For example, if Tom, Susan, and Hugh are members of a three-person nominal group and both Tom and...