Age dependence of sensory and motor components in saccades

Humans usually perform about 3-4 saccades per second; hence, precision as w ell as latency and velocity of these fast eye movements are of crucial impo rtance for analyzing complex and fast changing visual scenes, for example i n traffic. Since visual performance is known to slowly decline with age, we investigated the effect of age on the most important characteristics of vi sually guided saccades. This investigation on age dependence of visually gu ided saccades included, for the first time, the gap condition, where the ol d fixation point disappears before the new one appears, allowing subjects t o prepare for a saccade. Saccadic latencies and intersaccadic intervals inc reased with age, while their peak velocities and gains decreased, especiall y for threshold-adjusted luminance of the targets. The gap condition, howev er, improved reaction times (latencies) most pronounced in the older age gr oups, bringing performance for these groups close to the performance level of the young groups. This indicates that the slowing down of saccadic react ion times with age is not predominantly a motor problem, but, according to a common interpretation of the gap effect, a problem of disengaging attenti on from the old fixation spot.