James, W. 1890. The Principles of Psychology. Vol. 1. Republished by Dover, New York 1950.
"Let me try to state those particulars which to my own consciousness seem indubitable and distinct. In the first place, the acts of attending, assenting, negating, making an effort, are felt as movements of something in my head. In many cases it is possible to describe these movements quite exactly. In attending to either an idea or a sensation belonging to a particular sense- sphere, the movement is the adjustment of the sense-organ, felt as it occurs. I cannot think in visual terms, for example, without feeling a fluctuating play of pressures, convergences, divergences, and accommodations in my eyeballs. The direction in which the object is conceived to lie determines the character of these movements, the feeling of which becomes, for my consciousness, identified with the manner in which I make myself ready to receive the visible thing. My brain appears to me as if all shot across with lines of direction, of which I have become conscious as my attention has shifted from one sense-organ to another, in passing to successive outer things, or in following trains of varying sense-ideas. When I try to remember or reflect, the movements in question, instead of being directed towards the periphery, seem to come from the periphery inwards and feel like a sort of withdrawal from the outer world. As far as I can detect, these feelings are due to an actual rolling outwards and upwards of the eyeballs, such as I believe occurs in me in sleep, and is the exact opposite of their action in fixating a physical thing. In reasoning, I find that I am apt to have a kind of vaguely localised diagram in my mind, with the various fractional objects of the thought disposed at particular points thereof; and the oscillations of my attention from one of them to another are most distinctly felt as alternations of direction occurring inside the head. (300)
"When we transfer the attention from objects of one sense to those of another, we have an indescribable feeling ... of altered direction or differently localised tension (Spanning). We feel a strain forward in the eyes, one directed sideways in the ears, increasing with the degree of attention and changing as we look at an object carefully or listen to something attentively.; and we speak accordingly of straining the attention. The difference is most plainly felt when the attention oscillates rapidly between eye and ear... But now I have, when I try to recall a picture of memory or fancy, a feeling perfectly analogous to that which I experience when I seek to apprehend a thing keenly by eye or ear; and this analogous feeling is very differently localised. While in sharpest possible attention to real objects ... the strain is plainly forwards, ... the case is different in memory or fancy, for here the feeling withdraws entirely from the external sense-organs, and seems rather to take refuge in that part of the head which the brain fills.. not according as I strain my attention forwards, but rather ... retract it backwards."[435 quoting Fechner]