Differential eye movements and greater pupil size during mental scene construction in autobiographical recall.

There is growing evidence supporting a role for eye movements during autobiographical recall, but their potential functionality remains unclear. We hypothesise that the oculomotor system facilitates the process of mental scene construction, in which complex scenes associated with an autobiographical event are generated and maintained during recall. To explore this, we examined spontaneous eye movements during retrieval of cued autobiographical memories. Participants' verbal descriptions of each memory were recorded in synchronisation with their eye movements and pupil size during recall. For each memory participants described the place (details of the environment where the event took place) and the event (details of what happened). Narratives were analyzed using the Autobiographical Interview procedure, which separated internal spatial (place) and non-spatial (event, thoughts and emotion) details. Eye movements during recall of spatial details had significantly higher fixation duration and smaller saccade amplitude and peak velocity, and a higher number of consecutive unidirectional saccades, in comparison to recall of non-spatial details. Recurrence quantification analysis indicated longer sequences of refixations and more repetitions of the same fixation pattern when participants described spatial details. Recall of spatial details was also associated with significantly greater pupil area. Overall findings are consistent with the spontaneous production of more structured saccade patterns and greater cognitive load during the recall of internal spatial episodic scene details in comparison to episodic non-spatial details. These results are consistent with the oculomotor system facilitating the activation and correct positioning of elements of a complex scene relative to other imagined elements during autobiographical recall.