SOME DETAILS CONCERNING SENSORY CHARACTERS
In the preceding chapters, the fact has been brought out that the intensity of sense data is not a fixed or absolute quantity, but is relative to the perceiving mechanism. The brightness of a light, for example, depends upon the adaptation of the eye; and the same light may be quite different in intensity for two different observers. This relativity applies not only to intensity, but also to the other quantitative characters. The pitch (extensity) of a tone, and the size of a retinal or dermal impression are determined in part by the physiological condition of the receptors, and their anatomical peculiarities. Congestion of the inner ear may raise the pitch of notes, and the extensity of a colored area varies in different parts of the retina. Duration, and position in time and space, are similarly conditional.
Quality, on the other hand, is not relative. Relativity always implies more or less of; and there is no variation of more or less in respect to quality. When we speak of more or less of a certain quality, we really mean more or less in intensity, extensity or duration, of a sense datum of the specified quality.
For example: a reddish purple color is said to have more red, and less blue, than a bluish purple. This means simply that the red color is more intense in the first combination and the blue less intense (proportionately) in the first combination than in the second. One pure red cannot be either more red or less red than another pure red. The differences in color associated with a given stimulus, according to the adaptation of the eye, are due solely to differences in the proportionate intensities of the component primary colors.
The stimuli of the sense data, however, are conceived as absolute, in spite of the quantitative variations in the sense data themselves. Regardless of the brightness of the light as seen by dif