III. PHYSIOLOGICAL FACTORS OF THE ATTENTION-PROCESS (IV.). (Conclusion.) BY W. MCDOUGALL. IN the third paper of this series J I brought forward some new and direct evidence of the important part played by motor activities in supporting and directing sensory attention, and I endeavoured to render more precise and definite current con- ceptions as to how they play this part. Several distinguished psychologists have been so impressed with the importance of these effects of motor activities that they have proposed to regard them as the only determinants of attention. Of these Prof. Eibot has advocated this view in the most thorough- going and explicit manner, in many passages of which the following is a typical example : " The motor manifestations are neither effects nor causes, but elements ; together with the state of consciousness which constitutes their subjective side, they are attention ".' 2 If I do not misunderstand Prof. Eibot, we are to believe that the arrival in the brain of reinforcing impulses by way of the nerves of the "muscular sense" is the principal and essential condition of all attention, a con- dition in the absence of which attention of any kind or degree would be impossible. Prof. Sully also has lent the weight of his authority to a rather less extreme form of this doctrine. 3 On the other hand, this doctrine has been destructively criti- cised by Prof. Stout, 4 and here I have only to bring forward some experimental evidence to support his contention, to show that, even in the simplest cases of sensory attention, the part played by motor adjustments is a secondary one, and that, as Stout puts it, " ' cerebro-ideational activity ' is the immediate and essential condition on which the direc- tion of thought depends. Sensory adjustment [i.e. motor adjustment of sense-organs] is merely an arrangement for 1 MIND, vol. xii., No. 48. 2 Psychology of Attention, p. 23. 3 Human Mind, p. 149. 4 Analytic Psychology, vol. i., p. 208.
