Does retrieval require effort? Effects of memory strength on pupil dilation.


This study investigates the relation between retrieval effort and relative memory strength by measuring phasic pupil dilation during retrieval tasks. The facts were studied once and tested during four repetitions in one of two repetition-interval conditions. We hypothesized that retrieval effort will decrease as the relative strength of a memory trace increases. Analysis of the phasic pupil response in the experiment shows a significant main effect of repetition interval. Furthermore an interaction effect between the number of repetitions and repetition interval was found, indicating that the difference in effort between short and long repetition intervals decreased as the number of rehearsals increased. These findings largely confirm our hypotheses and the assumptions of theories that assume that increased retrieval effort increases learning gains.

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