The moderating influence of physical fitness on age gradients in vigilance and serial choice responding tasks.

The moderating influence of physical fitness on age gradients in measures obtained from vigilance and serial choice responding tasks is examined in a sample of 90 postal workers. Physiological data relating to aerobic fitness determined fitness level within 2 age groups: younger participants ages 18 to 30 years (M = 25.19; 24 men, 24 women) and older participants ages 43 to 62 years (M = 49.19; 20 men, 22 women). A performance decrement across time was found in several measures, and some variation as a function of age was apparent. However, post hoc statistical analyses did not indicate this was due to older adults underperforming younger adults. According to predictions, significant Age x Fitness interactions showed older less fit workers to consistently underperform other participants. The findings suggest that older less fit individuals have lower signal sensitivity and processing speed than older fitter people and younger individuals. Results are discussed in relation to underlying physiological mechanisms.