O1‐08‐04: perceptual guidance improves visual search in aging and in alzheimer's disease: evidence from eye‐movement behavior within real‐world scenes

Elderly people and, especially, patients with Alzheimer's disease (AD) show impaired performance in visual search. This seems to arise from inefficient strategies, with an increased number of eye fixations and longer fixation durations. As many activities of daily living require efficient search of objects within complex environments, visual search deficits of AD patients may have a key role in reducing their functional autonomy. However, while previous studies have examined patients’ search in simple object arrays, little is know about their search behaviour in real-world scenes. Using an EyeLink 1000, we recorded eye movements of 12 mild AD patients, 24 healthy age-matched individuals (“elderly controls”) and 32 young individuals (“young controls”) during search within real-world scenes. We examined whether any group difference in eye guidance during search depends on target template specificity (name vs. precise picture), target visual salience (low vs. high) and reliability of scene semantics (consistent vs. inconsistent targets). We analysed data using linear mixed effect models, considering search initiation (first search saccade), scene scanning (until first target fixations) and target verification (dwell time on target). Aging (elderly vs. young controls) and AD (patients vs. elderly controls) led to less effective behaviour in all search phases, with fewer first saccades directed toward the target, longer scanning time and longer verification time. While these patterns were not affected by scene semantic guidance, a greater amount of target perceptual guidance was especially beneficial for the elderly controls and, even more, for the AD patients. In particular, higher target salience reduced performance gaps between elderly and young controls during scene scanning and target verification, and – when combined with a pictorial template – between patients and elderly controls during scene scanning. Eye-movement analysis enables to examine the time course of fine impairments during real-world scene search. Enhancing target visual salience and providing a priori knowledge of the perceptual appearance of the specific target objects seem promising ways of improving visual search behaviour in healthy elderly individuals and in AD patients. This understanding may contribute to the development of more appropriate information systems and living places, promoting individual's everyday functional autonomy.