Three Semantic Serial Position Functions at the Same Time.

Serial position functions are so ubiquitous that researchers frequently use buffer items to control for primacy and recency effects regardless of the memory task. However, most theories offer different explanations for different types of tests. In contrast, the relative distinctiveness principle offers one explanation for all tasks: items with fewer close neighbors will generally be more distinct and therefore better remembered than items with more close neighbors. An experiment assessed two predictions of this account. (1) When undergraduates place seven US states in three different orders (by area, year of statehood, and population), serial position functions and error gradients will be observed that resemble those observed in episodic tasks. (2) States that are accurately placed in order because they are an early or late item on one dimension will be placed in order far less accurately when they become mid-list items on a different dimension. The results confirm both predictions.