Investigating the mediating effects of working memory and processing speed on age-related differences in visual path integration

Working memory and processing speed were previously shown to mediate the effect of age on real-world path integration performance, and the current study investigated whether such mediating effects could similarly apply to visual path integration in a virtual environment. Neuropsychological assessment showed letter-number sequencing performance as the only working memory variable that mediated the effect of age on path integration performance. Self-reported computer experience, performance in another test of working memory (spatial span), and tests of processing speed (letter and number comparisons), and verbal memory (California Verbal Learning Test), all failed to mediate the age effects on path integration performance. Taken together, we interpreted these findings as representing a divergence between the visuospatial processes engaged when performing the spatial span and visual path integration tasks, and that the cognitive test measures of processing speed might be less sensitive to visual path integration performance, which indexed less perceptual processing than real-world path integration due to the absence of proprioceptive cues. Importantly, this study demonstrated path integration as an inherently complex navigation task that may engage cognitive processes or functions differently under distinct environmental or testing conditions. As a marked decline in path integration ability is commonly observed among older adults who are at risk of developing Alzheimer’s disease (AD), the current findings will have positive benefits for future studies that aim to pinpoint the cognitive processes or factors that mediate or underlie the navigational difficulties of aged individuals with incipient AD.