Figure 1. The lag-recency effect.

a. Lag-CRP function averaged across 11 free recall studies. The lag-CRP measures the probability of recalling an item from position i+lag immediately following an item from position i. The contiguity effect can be seen in the finding that lag-CRP curves are peaked around zero. Asymmetry can be seen by noting that transitions in the forward direction (e.g. +1) are more likely than transitions in the backward direction (e.g. −1). Error bars are standard errors calculated across the experiments which varied widely in their procedures. b. The three components that combine to produce the lag-CRP. The newly learned component, weighted by α_N, provides a symmetric retrieval cue to the neighbors of the just-recalled item (filled circles). The pre-experimental component, weighted by α_O, provides an asymmetric retrieval cue (open circles). A noise component, weighted by η, does not overlap with the study context of any of the list items (filled diamonds). The contribution of the noise component has been offset slightly for clarity. c. Best-fitting parameter values for the three components for younger (filled bars) and older (open bars) adults. Older adults showed increased noise, consistent with disrupted associations. However, rather than being distributed evenly across the two beneficial components, the fits to older adults data showed a decrease only in α_N, accompanied by a small increase in α_O.