438 PSTCROLOGT. 



"Now it is interesting," he says, "to find that, although we keep 

 steadily fixating the pin-lioles and never allow their combined image to 

 break into two, we can, nevertheless, before the spark comes, keep our 

 attention voluntarily turned to any particular portion we please of the 

 dark field, so as then, when the spark comes, to receive an impression 

 only from such parts of the picture as lie in this region. In this respect, 

 then, our attention is quite independent of the position and accommo- 

 dation of ths- eyes, and of any known alteration in these organs; and 

 free to direct itself by a conscious and voluntary effort upon any selected 

 portion of a dark and undifferenced field of view. This is one of the 

 most important observations for a future theory of attention." * 



Hering, lioAvever, adds the followiug detail : 



" Whilst attending to the marginal object we must always," he says, 

 " attend at the same time to the object directly fixated. If even for a 

 single instant we let the latter slip out of our mind, our eye moves 

 towards the former, as may be easily recognized by the after-images 

 pi'oduced, or by the muscular sounds heard. The case is then less 

 properly to be called one of translocation, than one of unusually wide 

 dispersion, of the attention, in which dispersion the largest share still 

 falls upon the thing directly looked at," t 



and consequently directly accommodated for. Accommoda- 

 tion exists here, then, as it does elsewhere, and without it 

 we should lose a part of our sense of attentive activity. In 

 fact, the strain of that activity (v^^hich is remarkably great in 

 the exj^eriment) is due in part to unusually strong contrac- 

 tions of the muscles needed to keep the eyeballs still, which 

 produce unw^onted feelings of pressure in those organs. 



2. But if the peripheral part of the picture in this ex- 

 periment be not physically accommodated for, what is meant 

 by its sharing our attention? What happens when we 

 * distribute ' or ' disperse ' the latter upon a thing for which 

 we remain unwilling to ' adjust ' ? This leads us to that 

 second feature in the process, the ' ideational preparation ' 

 of which we spoke. The effort to attend to the marginal 

 region of the picture consists in nothing more nor less than the 

 effort to form as dear an idea as is possible of ivhat is there 

 portrayed. The idea is to come to the help of the sensation 

 and make it more distinct. It comes with effort, and such 

 a mode of coming is the remaining part of what we know as 



* Physiol. Optik, p. 741. 



•j- Hermann's Handbuch, iii. i. 548. 



