Longitudinal age changes in vigilance over an eighteen year interval.

An 18-year longitudinal repeat of the Mackworth Clock vigilance experiment was conducted. Skin potential response latencies (SPRL) and reaction times were taken from 33 men during the vigilance task. The longitudinal change in this study reproduced the earlier cross-sectional relationship. The 51 to 69 year olds showed faster reaction times, the 70 to 88 year olds showed slower reaction times and, the 70 to 88 year olds detected significantly fewer targets than when 18 years younger. It was found that the greater the change noted in this study reflected previously determined cross-sectional SPRL effect. However, the SPRL outcome was equivocated by a time-of-measurement effect. It was concluded that at about age 70 years a noticeable reduction in vigilance performance occurs, and this is accompanied by a reduction in autonomic and central nervous system reactivity.