Age-related differences in perceptual and mental imagery abilities.

Introduction: Previous studies have demonstrated the existence of two visual processing pathways in monkeys, healthy human participants, and patients with brain lesions. The dorsal and ventral visual pathways are involved in the perception of spatial locations and object recognition, respectively. Recent studies have challenged the idea that these two pathways are entirely segregated; however, their predominant roles in vision have not been questioned. The purpose of. this study was to investigate age-related differences in perceptual and mental imagery abilities. Methods: The Imagery Processing Battery (IPB), which includes 15 tasks for assessing different aspects of dorsal (spatial properties) and ventral (object properties) processing was used. Mean response times for each perceptual task were correlated with each other to obtain a correlation matrix; the corresponding correlation matrix was computed for the imagery tasks. Results: ANOVAs indicated that for the dorsal tasks, elderly participants were generally slower and made more errors than young participants, particularly in the imagery conditions. For the ventral tasks, older participants were slower but as accurate as young participants. These results remained unchanged when the simplest version of the generalized slowing hypothesis was tested using logarithmic response times. Nonmetric multidimensional scaling (MDS) of these correlation matrices in imagery and perception indicated the presence of two clusters, reflecting the dorsal/ventral nature of the tasks. However, the clusters based on data from the elderly were not as clearly defined as those based on data from the young. Discussion: These results suggest perceptual and mental imagery age-related changes in old as compared to young participants.