A Comparative Analysis of Eye Movement Accuracy for Locating Items Held in Visual Short-Term Memory Among Young Healthy Adults, Older Adults With Normal Cognition, and Older Adults Indicative of Mild Cognitive Impairment

BACKGROUND: We compared the accuracy of eye movements in locating an item stored in visual short-term memory between young healthy adults, normally aging older adults, and older adults with mild cognitive impairment as indicated by the Montreal Cognitive Assessment or Addenbrooke's Cognitive Examination-III test. METHODS: Thirty-three young healthy adults, 38 normally aging older adults, and 17 older adults indicative of MCI completed two experiments requiring object-location binding. In Experiment 1, participants viewed 2-4 memory items displayed sequentially at random screen locations. Following a 900 ms interval, eye movements were recorded while participants moved their eyes to the location of the memory item corresponding to a displayed cue. In Experiment 2 (control), participants indicated whether or not the test item was shown at its original location using a yes/no response. RESULTS: MCI-indicative participants exhibited greater saccadic error (spatial deviation of saccadic endpoint from the remembered target location) than normally aging older (p = 0.002) and young (p < 0.001) participants at low memory load only. At higher memory load, the saccadic error distance was greater for all groups (p < 0.001). Moreover, in Experiment 2, MCI-indicative participants exhibited significantly poorer memory performance than normally aging older adults, but only at lower memory load (p = 0.02). CONCLUSION: Saccadic accuracy declined with memory load for all groups. The MCI-indicative group showed lower saccadic accuracy versus normally aging older and young adults at low memory load. The findings offer important insights into our understanding of saccadic eye movement as a potential behavioral marker for MCI.