Semantic Interference Mechanisms on Long-Term Visual Memory and Their Eye-Movement Signatures in Mild Cognitive Impairment

Objective: Long-term visual memory representations, measured by recognition performance, degrade as a function of semantic interference, and their strength is related to eye-movement responses. Even though clinical research has examined interference mechanisms in pathological cognitive aging and explored the diagnostic potential of eye-movements in this context, little is known about their interaction in long-term visual memory. Method: An eye-tracking study compared a Mild Cognitive Impaired group with healthy adults. Participants watched a stream of 129 naturalistic images from different semantic categories, presented at different frequencies (1, 6, 12, 24) to induce semantic interference (SI), then asked in a 2-Alternative Forced Choice paradigm to verbally recognize the scene they remembered (old/novel). Results: Recognition accuracy of both groups was negatively impacted by SI, especially in healthy adults. A wider distribution of overt attention across the scene predicted better recognition, especially by the Mild Cognitive Impaired (MCI) participants, although these fixation patterns were influenced by SI. MCI compensated the detrimental effect of SI by focusing overt attention during encoding and so accruing distinctive details of the scene. During recognition, MCI participants widened overt attention to boost retrieval. Independently of the group: (a) the re-instatement of fixations indicated a more successful recall and increased as a function of SI; and (b) attending visually salient regions negatively impacted on recognition accuracy, although the reliance on such regions grew as SI increased. Conclusions: Effects of SI on long-term memory were reduced in MCI participants. They used different oculomotor strategies compared to healthy adults to compensate for its detrimental effects. Key Points Question: Is visual memory of Mild Cognitive Impaired participants impacted by semantic interference similarly to healthy adults, and will their eye-movements reveal any difference? Findings: Semantic interference effects are reduced in people with MCI and their eye-movements show subtle compensatory strategies associated with the formation and access of visual memories. Importance: Visual semantic interference may be an interesting candidate mechanism to better study pathological memory processes. Next Steps: Better characterize the nature of visual interference by developing new metrics to disentangle its perceptual and conceptual components.