Learning and memory for sequences of pictures, words, and spatial locations: an exploration of serial position effects.

A serial reproduction of order with distractors task was developed to make it possible to observe successive snapshots of the learning process at each serial position. The new task was used to explore the effect of several variables on serial memory performance: stimulus content (words, blanks, and pictures), presentation condition (spatial information vs. none), semantically categorized item clustering (grouped vs. ungrouped), and number of distractors relative to targets (none, equal, double). These encoding and retrieval variables, along with learning attempt number, affected both overall performance levels and the shape of the serial position function, although a large and extensive primacy advantage and a small 1-item recency advantage were found in each case. These results were explained well by a version of the scale-independent memory, perception, and learning model that accounted for improved performance by increasing the value of only a single parameter that reflects reduced interference from distant items.