Encoding dynamics in free recall: Examining attention allocation with pupillometry.

In four experiments pupillary responses were used to examine attention allocation and encoding dynamics in free recall. In Experiment 1, pupillary responses increased (and then decreased) across serial position suggesting that attention was increasingly allocated to items during learning until working memory was overloaded. In Experiment 2, manipulating presentation duration resulted in larger and more sustained pupillary responses with increased presentation duration, suggesting that participants were likely engaging in more elaborative and attention-demanding processes. In Experiment 3a, manipulating list-length resulted in decreased pupillary responses across serial position suggesting that participants were prioritizing early list items and less attention was allocated to later items. In Experiment 3b, when list-length was known, pupillary responses in the long-list length condition tended to decrease across serial position whereas pupillary responses in the short list-length condition tended to increase and decrease across serial positon. These results suggest that participants flexibly allocate attention to items during encoding depending on the nature of the task and the types of processes that are engaged in. These results further suggest the potential of utilizing pupillary responses to track attention allocation during learning.