Pupil dilation as an index of episodic processing when remembering, imagining, and thinking creatively

Prior research indicates that the cognitive and neural systems supporting the recall of specific past experiences (episodic memory) also play a key role in imagining novel and specific future experiences (episodic simulation), and divergent creative thinking. In particular, constructive memory processes (e.g. retrieval and recombination of specific episodic details) are thought to benefit episodic simulation and divergent thinking. In the current study, we provide a novel test of this hypothesis using eye-tracking. We capitalized on prior eye-tracking and neuroimaging evidence demonstrating that pupil dilation and hippocampal activity are enhanced when memory is associated with the retrieval of episodic detail relative to non-episodic detail. We tracked pupil dilation as participants recalled past experiences, imagined novel future experiences, engaged in divergent thinking, or performed a non-episodic/semantic retrieval task. Pupil dilation tracked divergent thinking ability and the number of episodic details generated during episodic memory and simulation. No relationship was observed between pupil dilation and performance in the semantic memory task, or the generation of non-episodic details during episodic memory and simulation. In contrast, fixation counts tracked performance in the semantic retrieval task. In line with prior findings, we interpret the results as reflecting the retrieval of specific information during episodic memory, simulation, and divergent thinking. At a broader level, these findings suggest that examining pupillometry is a promising direction for identifying common episodic processes.