Conditional Response Probabilities Confirm Two Stages of Free Recall, Working Memory Very Localized, Second Stage Delocalized, Both with Strong Tendencies to Forward Subsequent Recalls

TL;DR

This study confirms the existence of two distinct stages in free recall, characterized by different patterns of forward and backward recall probabilities, with working memory capacity estimated at approximately 4.5 items.

Contribution

It provides empirical evidence supporting the two-stage model of free recall using detailed analysis of conditional response probabilities.

Findings

First stage shows strong forward bias and suppression of backward recalls.

Second stage exhibits moderate forward bias with more delocalized recall patterns.

Working memory capacity is estimated at about 4.5 items.

Abstract

Recently it was shown that free recall consists of two stages: the first few recalls empty working memory and a second stage concludes the recall (Tarnow, 2015; for a review of the theoretical prediction see Murdock, 1974). Here I investigate conditional response probabilities in Murdock's 40-1 (1962) free recall dataset. I find that the conditional response probabilities confirm the presence of two stages. The first stage is characterized by a large enhancement of the forward subsequent recall (up to 30 times chance) and a large suppression of backward recalls (up to 26 times smaller than chance for recalls between 10 and 40 items away). The second stage forward subsequent recall is enhanced by a factor of 5 and the probability of backward and forward recalls are concentrated at small distances. Thus both stages favor forward subsequent recalls. As in Tarnow (2015), the first stage is much more localized than the second stage. Working memory capacity is estimated in six ways to be about 4.5 word items for the 40-1 word list.