The forest, the trees, and the leaves across adulthood: Age-related changes on a visual search task containing three-level hierarchical stimuli

Abstract

Selecting relevant visual information in complex scenes by processing either global information or local parts helps us act efficiently within our environment and achieve goals. A global advantage (faster global than local processing) and global interference (global processing interferes with local processing) comprise an evidentiary global precedence phenomenon in early adulthood. However, the impact of healthy aging on this phenomenon remains unclear. As such, we collected behavioral data during a visual search task, including three-levels hierarchical stimuli (i.e., global, intermediate, and local levels) with several hierarchical distractors, in 50 healthy adults (26 younger (mean age: 26 years) and 24 older (mean age: 62 years)). Results revealed that processing information presented at the global and intermediate levels was independent of age. Conversely, older adults were slower for local processing compared to the younger adults, suggesting lower efficiency to deal with visual distractors during detail-oriented visual search. Although healthy older adults continued exhibiting a global precedence phenomenon, they were disproportionately less efficient during local aspects of information processing, especially when multiple visual information was displayed. Our results could have important implications for many life situations by suggesting that visual information processing is impacted by healthy aging, even with similar visual stimuli objectively presented.

Keywords: Healthy aging; Hierarchical stimuli; Local versus global; Visual processing.

Fig. 1

Hierarchical stimuli with three hierarchical levels. In the task used in the present experiment, a square is the predefined target and could be absent (left) or present at global, intermediate or local levels

Fig. 2

Example of present-target trials. Here, an example of a target present at the global level with three distractors is presented. It should be noted that targets could appear equally often at the global level, the intermediate level or the local level, and there could be zero, one, three or five distractors in the display

Fig. 3

Interaction between the age group and the attentional level of the target occurrence in present-target trials (left panel) and between the age group and the number of distractors in present-target trials (right panel). *p <.05, ***p<.001, ns = non-significant, error bars indicate standard errors of the means. RTs: Response Times. All statistics have been corrected for multiple comparisons.

Fig. 4

Response times by attentional level and number of distractors in present-target trials, in each age group. The RT x Set size slopes for each level are indicated in grey. *p <.05, **p <.01, ns = non-significant, error bars indicate standard errors of the mean. All statistics have been corrected for multiple comparisons. The p values mentioned on the target legend refer to group x number of distractors interactions

Fig. 5

Response times by number of stimuli in absent-target trials, in each age group. ***p <.001, ns = non-significant, error bars indicate standard errors of the means. All statistics have been corrected for multiple comparisons.