Age-related differences in embodiment under visually deprived conditions in healthy aging: A tool-use study

In our prior research, we found that higher ratings of ownership were associated with increased body schema (BS) plasticity during virtual tool-use training in younger healthy adults. However, in older adults, the emergence of ownership remained stable, and no incorporation of virtual tools was observed. Moreover, an increased sense of agency in older adults depended on virtual tool-use training, which relied on visuo-tactile feedback compared to vision only feedback condition, and participants’ learning performance. In contrast, a sense of agency in younger adults emerged independently of these factors. In this study, we tested whether training temporarily visually deprived (blindfolded) participants with a cane affects emergence of ownership and agency over the cane, and if this relates to BS of the hand within the perceived space. For this study, datasets from a total of 43 healthy young and older adults who underwent two conditions of tool-use training were analyzed. Training conditions were as follows: (Condition A) while blindfolded, using a cane to find a target object with no time restriction; and (Condition B) walking blindfolded with a cane for 20 minutes. Older adults had 10 minutes of training in conditions B. Changes in the BS were assessed using a tactile distance judgment task (TDJ), where participants judged distances between two tactile stimuli applied to their right hand in a proximodistal orientation. Plasticity of peripersonal space (PPS) was assessed using a reaching distance estimation task (RDE). Participants further rated their perceived ownership and agency after training blocks A and B. Results revealed while young adults demonstrated stronger adaptability and control across conditions, older adults showed resilience by employing alternative strategies in the absence of visual input relying more on incorporation of cane and space around them. This study highlights age-related differences in sensory processing and motor adaptation under visually deprived conditions.Keyword: Tool-use, young adults, old adults, vision, blindfolded, body schema, peripersonal space, sense of ownership and agency