Generalized slowing in sinusoidal tracking by older adults.

Older and younger adults manually tracked sinusoidal input signals. Older adults exhibited 2 forms of slowing. First, they lagged behind the target somewhat more than younger adults. Second, they made considerably smaller movements than the younger adults. Because the velocity of a sinusoidal pattern is proportional to its amplitude, these smaller movements were also slower. Both older and younger adults made smaller movements with a compensatory display and with higher frequency inputs. The high degree of proportionality among these effects was taken as evidence for generalized slowing by the older adults. This slowing may prevent older adults from successfully adjusting an internal pattern generator to match their motions to the sinusoidal input signal.