Effects of list length on short-term memory

A memory experiment has been performed with the following procedure. On each trial of the experiment a display of items was presented in a serial order. At the conclusion of each display S was tested for recall on one of the items. The length of the displays varied from 3 to 14 items. Plotted as serial position curves, the results showed an S-shaped recency effect and a smaller primacy effect. A specific version of a memory model formulated by Atkinson and Shiffrin (1965) was presented and applied to the data. The model assumes two memory states: a temporary storage state, called the buffer, from which retrieval is perfect; and a long-term storage state called LTS, from which retrieval is imperfect. Both response data and confidence ratings were accurately fit by the model.