Croonian lecture.—Studies in visual sensation
Conwy Lloyd Morgan · Proceedings of the Royal Society of London · 1901
Abstract Peculiar difficulties are encountered when any attempt is made to express the relative values of sensations in quantitative terms which shall make some approach to exactness. No doubt we commonly deal with the less and the more of sensation; we say that a surface appears duller or brighter; but on what scale shall we determine with any precision how much the less, or by what amount the more ? What is to be our unit of sensation in terms of which we can reckon our gains and our losses ? At first sight it may seem reasonable to assume that the unit of sensation is that which corresponds to some definite and constant amount of physical stimulus or physiological excitation. And unquestionably we seem justified in asserting that under constant conditions, physical and physiological, a given amount of stimulus produces an amount of sensation which is constant in quantity. If it be not so the relation of stimulus to sensation is not a subject that is open to scientific investigation.