Eye Movement-Based Memory Assessment: The Use of Eye Movement Monitoring as an Indirect Measure of Memory
"Here, I introduce a new indirect measure of memory based on eye movement monitoring. Effects observed in eye movement data collected while participants were viewing images of faces showed that viewers process repeated items differently than novel items. Experiment 1 shows that this ""eye movement-based memory effect"" is observed by repeated items being viewed with fewer eye fixations made to fewer regions with lower ""constraint"" in the eye movement transition patterns between regions of the face. I discuss this concept of ""constraint,"" showing that viewers perform idiosyncratic, but stereotypic scanning when viewing novel items, leading to highly ""constrained"" or patterned eye movement traces. This is exemplified by the highly constrained patterns observed when participants are asked to perform certain ""scanpaths"" to faces in Experiment 2. In the viewing of repeated items, however, the eye is less constrained, due to a tuning of perceptual processors to individual characteristics of the face being viewed repeatedly. Experiment 3 shows that the eye movement-based memory effect scales with the amount of prior exposure, and shows that these effects can be observed even when using the same images as repeated or novel items, between participants. Experiments 4 and 5 show that these effects of prior exposure are observed separately from explicit remembering. By testing college-aged participants at a delay and by testing amnesic patients, I show that manipulations of explicit remembering fail to change the eye movement-based memory effect. Experiment 6 shows how this technique can be applied to other direct and indirect measures of memory by testing normal and amnesic individuals in the ""visual paired comparison task."" As expected, a normal eye movement-based memory effect is observed in both normal and amnesic participants, but declarative memory for the faces is impaired in amnesic patients. Overall, I argue that the eye movement-based memory effect can provide a useful index of procedural memory and that the use of eye movement measures as an indirect measure of memory provides what may be the first direct evidence in humans that previous experience does indeed change the nature of perceptual processing."
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign