Using a Landolt ring with a gap of 40' of arc which moved at a decreasing velocity until the gap was discriminated, we measured the dynamic visual acuity of 826 subjects, males and females ages 5 to 92 years, and found rapid development between the ages of 5 and 15 years. This experiment showed that dynamic discrimination peaked at age 15 and then declined at a constant rate from age 20 on. The discrimination of male subjects was superior to that of female subjects at most ages, but a significant sex difference was observed only at age 5. We speculate that males may have better discrimination than females but variability is substantial.