How does ageing affect grasp adaptation to a visual–haptic size conflict?

Abstract

Previous research suggests that the ability to adapt motor behaviour to sudden environmental changes may be impaired in older adults. Here, we investigated whether the adaptation of grasping behaviour in response to a visual–haptic size conflict is also affected by increasing age. 30 older and 18 young adults were instructed to grasp a hidden block whilst viewing a second block in a congruent position. Initially block sizes were equal, but after a set number of trials a sensory conflict was introduced by covertly changing the hidden block for a smaller or larger block. The scale and speed of maximum grasp aperture adaptation to the increase or decrease in the size of the hidden block was measured. Older adults successfully adapted to the visual–haptic size conflict in a similar manner to young adults, despite a tendency to adapt less when the hidden block increased in size. This finding is attributed to the physical capabilities of the grasping hand of older adults, rather than an effect of age-related sensory or cognitive decline. The speed of grasp adaptation did not differ between age groups; however, awareness of the visual–haptic conflict lead to faster adaptation. These findings suggest that sensorimotor adaptation for grasping is intact for cognitively healthy older adults.

The Effect of Ageing on Optimal Integration of Conflicting and Non-Conflicting Visual–Haptic Stimuli

“…Since participants in the study by Gori and colleagues (2008) did not notice the visual-haptic size conflict, it was expected that participants in the current study wouldn't notice the conflict either, and so were not asked whether they noticed the conflict at the end of the experiment. In addition, this study was part of a larger project which included experiments with similar visual-haptic manipulations (see Couth et al, 2018b), and so we did not want to bias participants' perceptions for future studies by questioning them about the conflict.…”

A study on how concurrent visual feedback affects motor learning of adjustability of grasping force in younger and older adults

“…This may be because various functional declines appear with ageing in older adults, and the degree of functional deterioration varies from person to person. First, when grasping an object in a new environment, it is necessary to adapt the condition of the fingers to that environment, but it has been reported that there is no significant difference between young and older people in grasping adaptation 19 . Next, memory is said to be associated with motor learning among the functions that decline with age, but the effects of general memory impairment are known to be small 20 – 22 .…”