4 PEOF. W. JAMES :

There are certain quasi-motor sensations in the head when we change the direction of the attention, which equally seem to involve three dimensions. If with closed eyes we think of the top of the house and then of the cellar, of the distance in front of us and then of that behind us, of space far to the right and then far to the left, we have something far stronger than an idea, an actual feeling, namely, as if something in the head moved into another direction. Fechner was, I believe, the first to publish any remarks on these feelings. He writes as follows : " When we transfer the attention from objects of one sense to those of another we have an indescribable feeling (though at the same time one perfectly determinate and reproducible at pleasure) of altered direction, or differently localised tension (Spannung). We feel a strain forward in the eyes, one directed sideways in the ears, increasing with the degree of our attention, and changing according as we look at an object carefully, or listen to something attentively ; wherefore we speak of straining the atten- tion. The difference is most plainly felt when the attention vibrates rapidly between eye and ear. This feeling localises itself with most decided difference in regard to the various sense-organs according as we wish to discriminate a thing delicately by touch, taste or smell. " But now I have, when I try to vividly recall a picture of memory or fancy, a feeling perfectly analogous to that which I experience when I seek to grasp a thing keenly by eye or ear ; and this analogous feeling is very differently localised. While in sharpest possible attention to real objects (as well as to after-images) the strain is plainly forwards, and, when the attention changes from one sense to another, only alters its direction between the sense-organs, leaving the rest of the head free from strain, 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. If I wish, for example, to recall a place or person it will arise before me with vividness, not according as I strain my attention forwards, but rather in proportion as I, so to speak, retract it backwards." 1 It appears probable that the feelings Fechner describes are in great part constituted by imaginary semi-circular canal sensations. 2 These undoubtedly convey the most delicate perception of change in direction ; and when, as here, the changes are not perceived as taking place in the external world, they occupy a vague internal space located within the head. 3 1 Elemente der Psychophysik, ii. 475-6. 2 See Foster's Text-book of Physiology, bk. iii., c. 6, 2. 3 Fechner, who was ignorant of the but lately discovered function of the semi-circular canals, gives a different explanation of the organic seat of these feelings. They are probably highly composite. With me, actual movements in the eyes play a considerable part in them, though I am wholly unconscious of the peculiar feelings in the scalp which Fechner goes on to describe thus : " The feeling of strained attention in the different sense-organs seems to be only a muscular one produced in using these