EXPRESS: Bore me (not): boredom impairs recognition memory but not the pupil old/new effect.

Mind-wandering and boredom are common phenomena, characterized by shifts in attention and difficulties in sustaining focus. Despite extensive research on the costs and benefits of these states, our understanding of the relationship between mind-wandering, boredom, attention, and memory remains limited. In the current study, we examined the impact that mind-wandering and boredom during encoding have on recognition. In particular, we investigated what impact mind-wandering and boredom have during the encoding of visual stimuli on the pupil old/new effect during recognition. We used an incidental memory task and measured mind-wandering and boredom with thought probes during encoding. Furthermore, we used the pupil old/new effect, assessed via eye-tracking, as a measure of recognition memory. We found a significant effect of boredom on recognition memory and observed the pupil old/new effect in participants regardless of instances of mind-wandering or boredom during encoding. Our findings point towards different mechanisms that underly mind-wandering and boredom's obstruction of attention during stimuli encoding and their effects on stimuli processing. In addition, these findings reinforce the idea of the pupil old/new effect as a reliable measure of recognition memory as it remained consistent irrespective of attentional lapses due to mind-wandering and boredom.