ABSTRACT
Weber was very interested in the sense of touch. In 1834 he ran some experiments on the perception of weight, and found that weight must be increased by a constant fraction of its value to be just noticeably different (JND). This constant fraction is about 1/40, and is independent of the magnitude of weight. In other words, if there is a 40 gram weight in one hand, there must be a 41 gram weight in the other hand to notice a difference between the two weights. If there is an 80 gram weight in one hand, there must be an 82 gram weight in the other hand to notice a difference. This became known as Weber's Law, AIII =constant, where I is the weight (intensity) and A1 is the increment that the weight must be increased to be just noticeably different.
