78 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Improvability. 
The improvement from day to day was not progressive, nor was it equal 
in the several test persons. The percentage increase between the first and 
second days varied from 1 1 to 37, and averaged 25 ; between the first and third 
days, from 22 to 48, and averaged 35 ; between the first and fourth days, 
from 30 to 58, and averaged 41 ; and between the first and fifth days, from 
38 to 70, and averaged 53. The average improvement between the first 
and third, first and fourth, and first and fifth days varied from each other 
by almost equal amounts. The four test persons who on the first day 
yielded the lowest number of units showed emphatically the most marked 
improvement in the course of the five days. Their average improvement 
for the whole test was 61 per cent., whereas the average of the other three 
was only 41. With normal people, therefore, the lower the initial output, 
the greater apparently is the capacity for improvement. The enormous 
gain on the second day undoubtedly arose in part at least from increased 
facility in writing. The psychomotor machine in the fifteen minutes’ 
working of the previous day had been “ tuned.” The tendency in the 
subsequent days was for the percentage increase progressively to diminish. 
All the persons together showed an average increase of 25*6 on the second 
day, 35 ’0 on the third, 41 -9 on the fourth, and 53*0 on the fifth. (Table I.) 
Table I. — Showing Initial Rate, Percentage Improvement between the First 
and Subsequent Days, and Percentage Rate op Variation prom Day to Day. 
(The percentage rate of variation is in reality the difference in the percentage gain between any 
two days. For full explanation see page 76.) 
Persons. 
Output 
on First 
Day. 
Percentage Improvement between 
First and Subsequent Days. 
Percentage Rate of Variation 
from Day to Day. 
Days. 
Days. 
2 
3 
; 4 
5 
2 
3 
4 
5 
A. 
610 
20-4 
32-9 
1 40-0 
54-2 
20*4 
10*3 
53 
104 
B. 
850 
24*3 
30*4 
30-0 
43T 
24-3 
4*9 
-0*3 
11-3 
C. 
694 
37-6 
48*5 
; 58-5 
70-2 
37-6 
8-4 
6*7 
7-4 
D. 
814 
17-7 
22-7 
34-9 
38-6 
17*7 
i 5*5 
8-6 
2*5 
E. 
718 
31*0 
41-5 
47-0 
60*7 
31-0 
7-9 
4-8 
8-3 
F. 
768 
11-4 
24*5 
321 
41-4 
11*4 
11*8 
6*0 
6‘9 
1 i 
642 
37-0 
45T 
51-0 
62*8 
37*0 
5-8 
4T 
73 
Average per person . 
25-6 
35 0 
41*9 
53-0 
25*6 
7-8 
5*0 
7-6 
