Abstract: With the method of gradually limiting speed by using a computer, we studied the relationship between quantity and speed of four cognitive tasksin aging. The subjects were 350 healthy volunteers of 46 to 75 years ofage. The results indicated: 1.The shorter the performance time limited bythe computer, the less the quantity accomplished in the four tasks withincreased age. 2. The order in sensitivity of the performance quantity acco-mplished in conditions of speeds limited to age was symbol-digit, arithmetic,count and digit discrimination, which was consistent with the order insensitivity of the performance speed to age.

Key words: analysis of gradually limiting speed, task quantity accomplished, performance speed, sensitivity to age