The "sensory" and the "motor" are becoming the most common descriptive terms of current psychology.

We hear all the while of sensory processes, sensory contents, sensory centres, sensory attention, etc.; and, on the other hand, of motor processes, motor centres, motor ataxy, motor attention, motor consciousness, etc.

And in the higher reaches of mental function, the same antithesis comes out in the contrast of sensory and motor aphasia, alexia, sensory and motor types of memory and imagination, etc.

Indeed the tendency is now strong to think that when we have assigned a given function of consciousness to one or other side of the nervous apparatus, making it either sensory or motor, then our duty to it is done.

Be that as it may, there is no doubt that the distinction is throwing great light on the questions of mind which involve also the correlative questions of the nervous system.