Many older adults notice that everyday tasks become more awkward with age — fumbling with keys, struggling to dial a phone, or accidentally knocking over a glass while reaching across the table.
Although these incidents are often attributed to declines in strength, balance, vision or reflexes, new research from Washington University in St. Louis points to an additional factor: changes in the mental reference frames older adults use to represent objects and space near their bodies. Those changes can alter how attention is allocated and how reaching movements are planned and executed.
“Reference frames help determine what in our environment we will pay attention to and they can affect how we interact with objects, such as controls for a car or dishes on a table,” said Richard Abrams, PhD, professor of psychology in Arts & Sciences and a co-author of the study. “Our results show that beyond physical and perceptual changes, older adults’ difficulties may also stem from differences in how they mentally represent nearby objects.”
Published in Psychological Science, the study was led by Emily K. Bloesch, PhD, with co-authors Christopher C. Davoli, PhD, and Richard A. Abrams, PhD. Bloesch, the lead author, is now a postdoctoral teaching associate at Central Michigan University; Davoli is a postdoctoral researcher at the University of Notre Dame.
Using a set of straightforward hand-movement tasks, the researchers found a clear difference between younger and older participants in how they focused attention during action. Younger adults tended to adopt an action-centered, or hand-centered, reference frame. That means their attention remained tied to the moving hand and to potential obstacles along the path of movement. Older adults, in contrast, were more likely to use a body-centered reference frame, directing attention toward objects based on their proximity to the torso rather than their relation to the moving hand.
“We showed in our paper that older adults do not use an ‘action-centered’ reference frame. Instead they use a ‘body-centered’ one,” Bloesch explained. “As a result, they might be less able to effectively adjust their reaching movements to avoid obstacles — which could explain why someone might topple a glass while reaching for a small item nearby.”
The behavioral findings align with existing neuroscience evidence showing age-related structural changes in brain regions that support visually guided hand actions and spatial attention. Older adults often show volumetric reductions in the parietal cortex and intraparietal sulcus, as well as white-matter loss within the parietal lobe and precuneus. Those areas contribute to visually guided reaching and to forming attentional reference frames used during action.
Because these neural systems are central to encoding and attending to the space immediately around the body, age-related deterioration could make an action-centered reference frame harder to use. The researchers suggest that young and older adults may therefore encode peripersonal space in fundamentally different ways — differences that have practical consequences for everyday tasks involving hand-eye coordination.
Understanding these cognitive and neural shifts is increasingly important as the population ages. Estimates indicate that a substantial portion of older adults report difficulty performing activities of daily living such as eating or bathing, and many experience impairments in goal-directed hand movements. By clarifying how spatial representation and attention change with age, this line of research may guide the development of targeted interventions, training programs or compensatory strategies that help older adults maintain independence and reduce accidents related to reaching and grasping.
Notes about this aging and neuropsychology research
This research was supported in part by Grant AG0030 from the National Institute on Aging.
Written by Gerry Everding
Contact: Gerry Everding – Washington University at St. Louis
Source: Washington University at St. Louis press release
Image source: The slip hazard sign image is available in the public domain.
Original research: Abstract for “Age-Related Changes in Attentional Reference Frames for Peripersonal Space” by Emily K. Bloesch, Christopher C. Davoli, and Richard A. Abrams in Psychological Science. Published online April 2013, doi: 10.1177/0956797612457385