Action & ageing

Abstract

Awareness of one's physical ability is critical when deciding on actions as attempting things beyond ability can result in mishap. This could be particularly important for the elderly as age-related changes bring a decline in sensorimotor performance and the potential to recover from injury is reduced.

A cohort of 430 subjects aged 70–90 years were studied. The theoretical aim is to identify the link between physiological sensorimotor function and psychological decision-making. The practical aim is to understand the causes of falls and pedestrian accidents, both major problems for the elderly.

Three tasks entailed a perceived physical hazard the choice of action determining risk taken. Good performance in each task meant taking more risk. The first task was to judge maximal reach and then attempt to retrieve an object at that distance. Risk taken by each subject was the difference between attempted and maximal reach. The second task was to walk to common destination as fast as possible by walking along one of six planks. Shorter routes had narrower planks. Risk taken was the probability of falling from the plank chosen determined by measuring foot placements in gait. The third task involved crossing a laboratory roadway but to perform well meant leaving short distance to cross in front of an approaching car. Risk taken was measured as the clearance distance.

General physical ability was measured across a wide range of physiological and cognitive tests. Falls were monitored prospectively for one year. Attitudes and behaviour in normal life on a cautious-daring spectrum were assessed by questionnaire. Consistent across all studies, people with good physical ability accurately matched ability and action to make low-risk choices but people with lesser ability were inaccurate, making either cautious or risky decisions. However, those who took low risks by these measures reported daring activity in daily life but those who took risks or were excessively timid reported being cautious in daily life.

It is concluded that decisions for action are intimately linked with physical ability. Risk taken in decisions reflects inability to predict outcomes through reduced physiological function rather than an inherent cautious-daring personality trait.