Eye movements to absent objects during mental imagery and visual memory in immersive virtual reality

The role of eye movements in mental imagery and visual memory is typically investigated by presenting stimuli or scenes on a two-dimensional (2D) computer screen. When questioned about objects that had previously been presented on-screen, people gaze back to the location of the stimuli, even though those regions are blank during retrieval. It remains unclear whether this behavior is limited to a highly controlled experimental setting using 2D screens or whether it also occurs in a more naturalistic setting. The present study aims to overcome this shortcoming. Three-dimensional (3D) objects were presented along a circular path in an immersive virtual room. During retrieval, participants were given two tasks: to visualize the objects, which they had encoded before, and to evaluate a statement about visual details of the object. We observed longer fixation duration in the area, on which the object was previously displayed, when compared to other possible target locations. However, in 89% of the time, participants fixated none of the predefined areas. On the one hand, this shows that looking at nothing may be overestimated in 2D screen-based paradigm, on the other hand, the looking at nothing effect was still present in the 3D immersive virtual reality setting, and thus it extends external validity of previous findings. Eye movements during retrieval reinstate spatial information of previously inspected stimuli.