You probably can detect a weight difference between a 1-ounce and a 2-ounce envelope. But if you pick up a 20-pound package, you'd probably need another package that weighs at least 20.5 pounds before detecting a difference between them. This description illustrates:

Question

Quizplus · Accepted Answer

Weber's law states that the smallest detectable difference in stimulus intensity (or weight in this example) is proportional to the magnitude of the stimulus. In this case, the weight difference between the 20-pound package and a slightly heavier one is so small that it falls within the range of the just noticeable difference according to Weber's law.

You Probably Can Detect a Weight Difference Between a 1-Ounce