THE PERCEPTION OF TIME. 613 



them by the attention was allowed — and practically it was 

 found impossible not to group tliem in at least this simplest 

 of all ways — 16 was the largest number that could be clearly 

 apprehended as a whole.* This would make 40 times 0.3 

 second, or 12 seconds, to be the maximum filled duration of 

 which we can be both distinctly and immediately aware. 



The maximum unfilled, or vaca7it duration, seems to lie 

 within the same objective range. Estel and Mehner, also 

 working in Wundt's laboratory, found it to vary from 5 or 

 6 to 12 seconds, and perhaps more. The differences seemed 

 due to practice rather than to idiosyncrasy, f 



These figures may be roughly taken to stand for the most 

 important part of what, with Mr. Clay, we called, a few 

 pages back, the specious present. The specious present has, 

 in addition, a vaguely vanishing backward and forward 

 fringe ; but its nucleus is probably the dozen seconds or 

 less that have just elapsed. 



If these are the maximum, what, then, is the minimum 

 amount of duration which we can distinctly feel ? 



The smallest figure experimentally ascertained was by 

 Exner, who distinctly heard the doubleness of two success- 

 ive clicks of a Savart's wheel, and of two successive snaps 



* Counting was of course not permitted. It would have given a sym- 

 bolic concept and no intuitive or immediate perception of the totality of 

 the series. With counting we may of course compare together series of 

 any length — series whose beginnings have faded from our mind, and of 

 whose totality we retain no sensible impression at all. To count a series of 

 clicks is an altogether different thing from merely perceiving them as dis- 

 continuous. In the latter case we need only be conscious of the bits of 

 empty duration between them ; in the former we must perform rapid acts 

 of association between them and as many names of numbers. 



f Estel in Wundt's Philosophische Studien, ii. 50. Mehner, ibid. ii. 

 571. In Dietze's experiments even numbers of strokes were better caught 

 than odd ones, by the ear. The rapidity of their sequence had a great influ- 

 ence on the result. At more than 4 seconds apart it was impossible to per- 

 ceive series of them as units in all (cf. Wuudt, Physiol. Psych., ii. 214). 

 They were simply counted as so many individual strokes. Below 0.21 to 

 0.11 second, according to the observer, judgment again became confused. 

 It was found that the rate of succession most favorable for grasping long 

 series was when the strokes were sounded at intervals of from 0.3" to 0.18' 

 apart. Series of 4, 6, 8, 16 were more easily identified than series of 10, 12, 

 14, 18. The latter could hardly be clearly grasped at all. Among odd 

 numbers, 3, 5, 7 were the series easiest caught ; next, 9, 15 ; hardest of all, 

 11 and 13 ; and 17 was impossible to apprehend 



