Again and again, philosophers stated unequivocally that psychology could never be a science.  The activities and the contents of the mind could not be measured, and therefore an objectivity such as that achieved in physics and chemistry was out of reach.  Psychology would forever remain subjective!

This would finally change in the early 1800s.  Ernst Weber (1795 to 1878) was born June 24 in Wittemburg, Germany, the third of 13 children!  He received his doctorate from the University of Leipzig in 1815, in physiology.  He began teaching there right after graduation, and continued until he retired in 1871.

His research was predominantly concerned with the senses of touch and kinesthesia (the experience of muscle position and movement).  He was the first to clearly demonstrate the existence of kinesthesia, and showed that touch was actually a conglomerate sense composed of senses for pressure, temperature, and pain.

His chosen interests led him to certain techniques:  First, there is the two-point threshold, which is a matter of measuring the smallest distance noticeable to touch at various parts of the body.  For example, the tongue had the smallest threshold (1 mm), and the back had the largest (60 mm).

A second technique involved kinesthesia:  Just-noticeable difference is the smallest difference in weight a person is capable of perceiving through holding two things.  He discovered that the just-noticeable difference was a constant fraction of the weights involved.  If you are holding a 40 pound weight in one hand, you will be able to recognize that a 41 pound weight in the other hand is in fact different.  But if it were a 20 pound weight, you could detect a mere half pound difference! In other words, as regards weight, we could recognize a 1/40 difference, whatever the weights.

This is known as Weber’s Law, and is the first such “law” relating a physical stimulus with a mental experience.