sensation and attributes
In the first decade of the present century the sensation was regarded as an element because it was supposedly the simplest bit of conscius content ideally isolable in experience. The attributes are not really isolable, because, if you take away all quality or all extension or all duration from, let us say, a visual sensation, you have no sensation left at all. Nevertheless the attributes must be independently variable or they cannot be regarded as separate attributes. That which is essential to the existence of a sensation, but which can be changed without change of other charactersistics, is an independent attribute of that sensation. In logical analysis the attribute and not the sensation is the mental element. . . . This preoccupation with sensation as the mental element caused psychologists for nealy half a century to overlook the fact that it is the attribute, and not the sensation, which becomes the object of observational attention. In all introspective work, wher ethe degree of precision is that of the psychophysical methods, the observer makes his judments of quality or of extent or of some other attribute, but not of the sensation as a whole. Kulpe (1904) realized this fact and raised the question as to whether the entire sensation ever actually exists as such in consciousness or whether it is not merely an inferred reality built up out of attributive fragments which are realized at different times. Rahn (1913) subsequently press this argument home, so that even Titchener (1915) was brought to explain that sensation is a logical systematic construct, while the attribute is the immediate introspective datum. Thus it came about that, just when the concept of sensation was losing its significance because it no longer served to classify a part of consciousness, the concept of the attribute provided differentiae to consciousness. The attributes gained systematic importance because they were - belatedly - discovered to be the actual observational data of the quantitative introspective experiment" (20-21, "The Physical Dimensions of Consciousness" Boring, E.)