Age-related loss of adaptability to fast time scales in motor variability.

We investigated the ability of older adults to intentionally adapt their sensorimotor output to differing time and frequency properties (1/f noise structure) of a target-force target waveform. We tested the hypothesis that elderly adults are less adaptable than their younger counterparts to the time- and frequency-dependent demands of continuous sensorimotor output and that this effect is mediated by the frequency content of the task demand. The results showed that older adults were progressively less able than young adults to approximate the lighter-color-noise force targets and utilize the information in the higher frequencies of the target signal. There is a declining ability with aging to use the faster time scales of sensorimotor control, but the particular directional effect of the loss or gain of complexity of force output is moderated by the differential impact of task demands.