@Article{LaengTeodorescu2002,
author = {Bruno Laeng and Dinu-Stefan Teodorescu},
title = {Eye scanpaths during visual imagery reenact those of perception of the same visual scene},
journal = {Cognitive Science},
year = {2002},
volume = {26},
pages = {207--231}
}
Eye movements exist not only to scan a given area/feature at a time, but also allow us to take in the entire visual field with high resolution (an illusion obtained from the synthesis of visual information captured successively by said eye movements) (Hebb 1968)
Why do overt eye movements occur during mental imagery (in the absence of the original sensory visual input)? Intuitively, it would seem that "internal" mental images should not require scanning by eye movements...so why do they still occur during mental imagery?
If eye movements are necessary during perception, and mental imagery is assumed to be a "reinstatement" of this process, we can also assume that eye movements also play a role in reconstructing the mental image (Hebb 1968, Neisser 1967)
Goal of the study
Laeng and Teodorescu conduct a study comprised of 2 experiments in order to confirm prior speculation by Hebb (1968), Neisser (1967) and replicate the results of a previous study run by Brandt & Stark (1997).
Methods: Participants, Apparatus and Stimuli
The participants in both experiments were students between the ages of 21-44 from the University of Tromso, Norway. All participants in both experiments reported normal vision (or corrected to normal vision with contact lenses). Eye movements in both experiments were recorded using Remote Eye Tracking Device, R.E.D., built by SMI-SensoMotoric Instruments from Teltow (Germany). [p211, 222]
Generally, a given trial of either experiment involves the participants being instructed to memorize an image (grid or a picture of natural object) in a set amount of time, and then visualize it (with their eyes open) once it has been removed.
Laeng and Teodorescu systematically vary the conditions in their experiments to distinguish their study from (and expand upon) the research done by Brandt & Stark in 1997. The main conditions varied are eye movement fixation (participants are asked to focus on a central point in order to minimize eye movement) or free exploring (no restriction on participants’ eye movements) during either the initial visual stimuli or mental imagery after visual stimuli has been removed.
An eye tracker is used to measure the eye scanpaths of all participants in all conditions, during both the stimuli and the mental imagery/recall tasks. Spatial memory is also tested by displaying numbers in some of the grids and observing any relationship between varying eye movement conditions and participants' recall/reporting of the numbers and their positions in the grids
Results and Discussion
Both experiments provide evidence of highly correlated patterns of oculomotor activity between perception and mental imagery. Eye scanpaths measures during mental image generation follow or reenact similar patterns to those during the initial perception phase.
The data collected indicates that unrestricted eye movements during initial perception of a picture and afterwards during mental imagery tasks involving that picture seems to aid in image generation and recall. Alternatively, a seeming disruption in recall occurs in the conditions where eye movement is restricted during the mental imagery tasks. This lends even more credence to eye movements' role in constructing mental images. [p227]
Laeng and Teodorescu also discuss their study's place in the emergence of a new paradigm of understanding of perception. Their study on eye movements and mental imagery indicates that an understanding of perception must account for HOW we direct and control attention (using motor control processes such as eye movements) to "explore" the targets of our senses and subsequently form, store and recall mental representations about them.[p229]