=Neural Basis of Attention.=--The neural conditions under which the mind exercises such active attention seem to be that during the attentive state the nervous energy concentrates itself upon the paths and centres involved in the particular experience, the resistance being decreased in the paths connecting the cells traversed by the impulse. Moreover, any nervous energy tending to escape in other channels is checked and the movements hindered, thus shutting off attention from other possible experiences. For instance, a person with little interest in horticulture might pass a flowering shrub, the colour, form, and scent making only a faint impression upon him. If, however, his companion should say, "What a lovely colour," his attention will direct itself to this quality, with the result that the colour stands out much more clearly in consciousness, and the other features practically escape his notice. Here the suggestion of the companion focuses attention upon the colour, this being accompanied with a lessening of the resistance between the centres involved in interpreting the colour sensations. At the same time resistance in the arcs involving form and smell is increased, and the energy diverted from these arcs into that of colour. ATTENTION SELECTIVE =Attention and Interest.=--At this point a question naturally arises why the mind, since it is continually subject to the influence of impressions from without and of reviving ideas from within, should select and focus attention upon certain of these to the exclusion of others. The answer usually given is that the mind feels in each case, at least vaguely, a personal interest in some change or adjustment to be wrought either in or through the impression which it makes an object of attention. When, for instance, the reader diverts his attention from the interesting story to the loud talking outside the window, he evidently desires to adjust his understanding more fully to the new and strange impression. So, also, when the spectator rivets his attention upon the flying ball, it is because he associates with this the interesting possibility of a change in the score. In like manner, the student in geometry fixes his attention upon the line joining the points of bisection of the sides, because he desires to change his present mental state of uncertainty as to its parallelism with the base into one of certainty. He further fixes his attention upon the qualities of certain bases and triangles, because through attending to these, he hopes to gain the desired experience concerning the parallelism of the two lines.