Top-down and bottom-up sources of eye-movement guidance during realistic scene search in Alzheimer's disease.

OBJECTIVE: Visual search is a crucial task in daily life, but in Alzheimer's disease (AD) it has usually been investigated using simple arrays. Here, we used scenes depicting real environments and studied the time course of attentional guidance. METHOD: We analyzed eye-movement differences between mild AD patients and age-matched healthy controls during search. We examined top-down guidance, manipulating the target template (precise picture vs. word cue) and the target-scene semantic consistency (consistent vs. inconsistent), and bottom-up guidance, manipulating the perceptual salience (high vs. low) of targets and distractors. RESULTS: During scene scanning, AD patients had longer search times, made more fixations before the first target fixation, and showed a greater probability of distractor selection, with longer distractor fixation. AD also led to longer target fixation. In patients and controls, picture cues and highly salient targets improved all search phases, whereas consistent targets only improved search initiation (first saccade). Moreover, top-down and bottom-up guidance interacted in initiation and scanning, and this did not differ between the two groups of participants. However, AD led to a smaller picture cue benefit in shortening distractor fixation and greater bottom-up search facilitation during scanning, where a high-salience target reduced the performance gap between patients and controls. CONCLUSIONS: Our study shows the importance of top-down and bottom-up guidance, and their integration, in improving search in AD patients. It suggests that precise target cues and, even more, highly salient targets may act as environmental supports that enhance attentional processing and search performance. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Age-related differences when searching in a real environment: The use of semantic contextual guidance and incidental object encoding.

Visual search is a crucial, everyday activity that declines with ageing. Here, referring to the environmental support account, we hypothesised that semantic contextual associations between the target and the neighbouring objects (e.g., a teacup near a tea bag and a spoon), acting as external cues, may counteract this decline. Moreover, when searching for a target, viewers may encode information about the co-present distractor objects, by simply looking at them. In everyday life, where viewers often search for several targets within the same environment, such distractor objects may often become targets of future searches. Thus, we examined whether incidentally fixating a target during previous trials, when it was a distractor, may also modulate the impact of ageing on search performance. We used everyday object arrays on tables in a real room, where healthy young and older adults had to search sequentially for multiple objects across different trials within the same array. We showed that search was quicker (1) in young than older adults; (2) for targets surrounded by semantically associated objects than unassociated objects, but only in older adults; and (3) for incidentally fixated targets than for targets that were not fixated when they were distractors, with no differences between young and older adults. These results suggest that older viewers use both environmental support based on object semantic associations and object information incidentally encoded to enhance efficiency of real-world search, even in relatively simple environments. This reduces, but does not eliminate, search decline related to ageing.

Top-down and bottom-up guidance in normal aging during scene search.

Age-related differences in visual search have been extensively studied using simple item arrays, showing an attentional decline. Little is known about how aging affects attentional guidance during search in more complex scenes. To study this issue, we analyzed eye-movement behavior in realistic scene search. We examined age-related differences in top-down guidance, manipulating target template specificity (picture vs. word cue) and target-scene semantic consistency (consistent vs. inconsistent), and in bottom-up guidance, manipulating perceptual salience (high vs. low) of targets and distractors. Compared to young adults (YA), older adults (OA) were overall slower, from the first saccade in the scene. They showed a smaller benefit of a specific target template, suggesting that precision of visual information in working memory may decrease with age. The benefit of semantic consistency did not depend on age, suggesting a preserved ability in OA to use knowledge about object occurrence in scenes. OA showed greater bottom-up search facilitation due to target's high salience, which may depend on reduced selection of low-salience stimuli. Attentional capture by distractors was greater in OA than YA, with respect to engagement (probability of distractor fixation), but only following a picture cue, and disengagement (fixation duration on distractors) in all conditions. Overall, our study shows that age-related differences in visual selection of targets and distractors depend on specific task demands in terms of top-down and bottom-up guidance. It also indicates that scene search difficulties in OA can be limited by cognitive and perceptual forms of environmental support. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

A compressibility account of the color-sharing bonus in working memory.

It has been established that objects sharing color in a visual display can boost working memory. The capacity to encode singletons particularly benefits from the repetition of colors encoded as perceptual groups. We manipulated the algorithmic complexity of visual displays to test whether compressibility of information could account for the color-sharing bonus. This study used a free recall working memory task in which the participants were shown displays of 2 to 8 color items. We examined the influence of set size, complexity, number of same-color clusters and amount of color redundancy. The results showed that the probability of correct recall of the pattern and the proportion of similarity between the pattern and the response decreased with an increase of each manipulated variable, except for color redundancy in terms of probability of correct recall. The model performance of complexity did not differ from that of clusters, but complexity was found more accurate than either set size or color redundancy. The results also showed that similar items were more often recalled adjacently, and complexity correlated strongly with the number of extra color repetitions in the response, suggesting that more complex patterns encouraged the use of information compression. Moreover, color repetitions were more often recalled first and the probability of correct recall for singletons and sub-patterns could be predicted by the compressibility measure. We discuss the potential advantage of using compressibility measures to capture the effects of regularities in visual patterns, in particular to refine analysis of the color-sharing bonus.

Alzheimer's Disease, Visual Search, and Instrumental Activities of Daily Living: A Review and a New Perspective on Attention and Eye Movements.

Many instrumental activities of daily living (IADLs), like cooking and managing finances and medications, involve finding efficiently and in a timely manner one or several objects within complex environments. They may thus be disrupted by visual search deficits. These deficits, present in Alzheimer's disease (AD) from its early stages, arise from impairments in multiple attentional and memory mechanisms. A growing body of research on visual search in AD has examined several factors underlying search impairments in simple arrays. Little is known about how AD patients search in real-world scenes and in real settings, and about how such impairments affect patients' functional autonomy. Here, we review studies on visuospatial attention and visual search in AD. We then consider why analysis of patients' oculomotor behavior is promising to improve understanding of the specific search deficits in AD, and of their role in impairing IADL performance. We also highlight why paradigms developed in research on real-world scenes and real settings in healthy individuals are valuable to investigate visual search in AD. Finally, we indicate future research directions that may offer new insights to improve visual search abilities and autonomy in AD patients.