IF you can just barely perceive a difference of one gram added to twenty grams, what is the smallest difference you can perceive when added to forty grams? Eighty grams? Two hundred grams?
Weber's law gives the answer: "Equal difference between sensations means proportional difference between stimuli." The ratio just posited is 1:20; hence 2 grams added to 40 grams, 4 grams added to 80 grams, and 10 grams added to 200 grams would be equally perceptible.
This law applies in various ways in the different senses. Weber first demonstrated it for the perception of weight, and as this field presents the simplest as well as the most exact conditions for measurement, we shall verify and illustrate the law for lifted weights.
Specifically, this is what we shall try to do: Exp. 1 is a preliminary skirmish to determine within what range of weight it will be most profitable to make the measurement on the observer; Exp. 2 reduces this to an exact measurement; and Exp. 3 makes the same measurement with doubled weight and doubled incre-____________________