Two processes control variations in flicker sensitivity over the life span.

Flicker thresholds were measured in an automated paradigm at several temporal frequencies for the critical fusion frequency in more than 1000 observers of ages 5-75 years. The results can be described by two processes. The first process was a uniform increase in sensitivity at all frequencies, at a rate that would double sensitivity every 10 years, up to the age of 16 years. In the second process the data indicated that after the age of 16 years the visual response showed gradual slowing but little sensitivity decrease for the remainder of the life span.