As a pioneer of experimental psychophysics, Ernest H. Weber noted that the skin registers changes in temperature, not constant readings. Similarly, he showed that if 2 pin points are placed close enough together, they are perceived as one pin prick. Weber had subjects hold weights in each hand and report whether they were identical or different. He found that people could not detect a change in weight until there was a 1:40 ratio. Weber’s jnd (just noticeable difference) was the first reliable law of psychophysics.