Individual differences in working memory capacity and long-term memory: The influence of intensity of attention to items at encoding as measured by pupil dilation

The present study used pupil dilation as an index of the intensity of attention to determine if variation in attention at encoding partially accounts for the relation between working memory capacity (WMC) and long-term memory (LTM). In Experiment 1, participants completed a delayed free recall task while pupil dilation was simultaneously recorded. Results revealed high WMC individuals displayed an increase in pupil dilation across serial positions, whereas low WMC individuals exhibited a decline in pupil dilation. Experiment 2 employed a similar method but manipulated encoding conditions via value-directed remembering. Results demonstrated when later serial positions were labeled as more important, the pupillary response no longer declined for low WMC individuals. Instead, low WMC individuals increased attention across serial positions, with the caveat being that these individuals devoted less attention than high WMC individuals to all items under these conditions. Overall, results support the notion that high WMC individuals outperform low WMC individuals in delayed free recall, which is partly explained by the amount of attention devoted to items at encoding.