Tracking the Mind's Eye

Abstract: This thesis investigates, in three studies based on eye-tracking experiments, the relationship between eye movements and mental imagery. The first study is an investigation of eye movements during mental imagery elicited both visually and verbally. The use of complex stimuli and the development of a novel method where eye movements were recorded concurrently with verbal data enabled this relationship to be studied to an extent going beyond what previous research had been able to do. Eye movements were found to closely reflect content and spatial layout while participants were listening to a spoken scene description, while they were retelling the same scene from memory, and while they were describing a picture they had previously seen. This effect was equally strong in retelling from memory irrespective of whether the scene visualised had originally been inspected visually by participants or whether it was constructed whole-cloth from long-term memory (on the basis of a spoken scene description that participants had previously listened to). It was also found that eye movements to “nothing” appeared both when participants were visualising scenes looking at a blank screen and when they were doing so in complete darkness. In the second study, participants had their eye movements restricted in that they were instructed to look at a fixation cross at the centre of the display while looking at a picture or listening to a spoken scene description. Results revealed that despite this central-fixation restriction during the encoding phase, participants’ eye movements spread out and reflected content and spatial layout during recall, both for the picture and for the spoken scene description. Consequently, eye movements during recall operate independently of those during encoding. The third study explored an effect frequently observed in both the first and the second study, involving a “scaling-down” during recall of participants’ gaze patterns to an area smaller than that occupied by the stimulus encoded. It was found that this scaling effect correlated with spatial-imagery ability: those with weaker spatial-imagery ability had gaze patterns that more closely resembled the original size of the encoded scene than those stronger in spatial-imagery ability. The present thesis concludes with a discussion of the findings from these studies in the light of current theories regarding eye movements during mental imagery and in the light of mental-imagery theories in general.