ATTENTION. 437 



The reader who doubts the presence of these organic feel- 

 ings is requested to read the whole of that passage again. 



It has been said, however, that we may attend to an 

 object on the periphery of the visual field and yet not 

 accommodate the eye for it. Teachers thus notice the acts 

 of children in the school-room at whom they appear not to 

 be looking. "Women in general train their peripheral visual 

 attention more than men. This would be an objection to 

 the invai'iahle and universal presence of movements of ad- 

 justment as ingredients of the attentive process. Usually,, 

 as is well known, no object lying in the marginal portions 

 of the field of vision can catch our attention without at the 

 same time ' catching our eye ' — that is, fatally provoking 

 such movements of rotation and accommodation as will 

 focus its image on the fovea, or point of greatest sensibility. 

 Practice, however, enables us, ivith effort, to attend to a 

 marginal object whilst keeping the ej^es immovable. The 

 object under these circumstances never becomes perfectly 

 distinct — the place of its image on the retina makes dis- 

 tinctness impossible — but (as anyone can satisfy himself by 

 trying) we become more \dvidly conscious of it than we were 

 before the effort was made. Helmholtz states the fact so 

 strikingly that I will quote his observation in full. He was 

 trying to combine in a single solid percept pairs of stereo- 

 scopic pictures illuminated instantaneously by the electric 

 spark. The pictures were in a dark box which the spark 

 from time to time lighted up ; and, to keep the eyes from 

 wandering betweenwhiles, a pin-hole was pricked through 

 the middle of each picture, through which the light of the 

 room came, so that each eye had presented to it during the 

 dark intervals a single bright point. With jjarallel optical 

 axes the points combined into a single image ; and the 

 slightest movement of the eyeballs was betraj^ed by this 

 image at once becoming double. Helmholtz now found 

 that simple linear figures could, when the eyes were thus 

 kept immovable, be perceived as solids at a single flash of 

 the spark. But when the figures were complicated photo- 

 graphs, many successive flashes were required to grasp 

 their totality. 



