J.—PSYCHOLOGY. 179 
more important for operations that are composite, the engines for those 
that are monotonous. This is natural enough. The composite operation 
really involves several different engines ; the superiority that an individual 
may happen to have in any one of them will tend to be neutralised in the 
average of them all; but a superiority in the energy will make itself felt 
in each, and thus obtain cumulative influence. Again, the energy is less 
and the engine more influential whenever the operation depends much 
upon the efficiency of some sensory or motor apparatus. This, too, is 
natural enough; for such apparatus obviously constitutes a part and 
parcel of the engine. Yet again the energy has been found to lose in 
importance as compared with the engine in proportion as the operation 
tends less to create new mental content and more to reproduce old. On 
this profoundly significant matter I need not dilate here, as it seems 
likely to be treated by Dr. McCrae later on. 
The point which I do wish to bring forward in this place is that the 
relative influence of the energy and the engines changes largely with the 
class of person at issue. The most drastic instance of this is supplied 
by a comparison between normal children and those who are mentally 
defective. The work of Abelson may be quoted, where the same tests 
were applied by the same experimenter to both classes. The correlations 
obtained for the two respectively are as follows : 
Norma CuHinpren. (78 Cassis.) 
Le 2i2F idk wt ey iene Oa il ee Seet OF £1 Os Rs 12 
1. Opposites .. ce <3 75 78 71 62 64 72 78 57 40 46 33 
2. Observation ne .. 75 72 58 60 58 67 56 58 56 52 29 
3. Absurdities a A 78 72 53 41 44 79 68 41 46 34 29 
4. Memory sentences -» 71 58 53 54 61 54 37 54 55 19 43 
5. Crossing 0’s om -- 62 60 41 54 73 48 54 38 36 52 35 
6. Geometrical figs. .. -. 64 58 44 61 73 45 48 30 42 48 35 
_ 7. Discrim. length .. .. 72 67 79 54 48 45 56 49 30 31 06 
8. Crossing patterns. . .. 78 56 68 37 54 48 56 30 21 27 18 
9. Memory form... .. 57 58 41 54 38 30 49 30 24 31 29 
10. Tapping .. ae -. 40 56 46 55 36 42 30 21 24 29 18 
11. Strength of grip -- 46 52 34 19 52 48 31 27 31 29 28 
12. Interpret. pictures -. 33 29 29 43 35 35 06 18 29 18 28 
Mean=.466. 
DEFECTIVE CHILDREN. (22 CAsEs.) 
(2c Ot ede ae SOM ie” Oe Oe lOn milan 
1. Absurdities OE HO’ TO ss OF Ho NO ie’ 98 ga gw 7g 
MeOpposites.. 5... LO 97 95 87 91 85 76 85 87 70 72 
3. Crossing patterns..  ..1.0 97 91 80 88 68 92 74 78 76 67 
4. Crossing 0’s ore a em | 85 77 84 67 76 81 73 55 
5. Memory sentences .. 97 87 80 85 73 90 68 88 65 78 68 
6. Observation eillows Ou Sb Asse oS 76 83 71 86 59 65 
7. Memory form .. ..1.0 85 68 84 90 76 65 67 70 77 75 
8. Interpret. pictures ..1.0 76 92 67 68 83 65 74 80 80 59 
9. Geometrical figs... .. 98 85 74 76 88 71 67 74 65 60 62 
10. Discrim. length .. .. 94 87 78 81 65 86 70 80 65 51 45 
ll. Tapping .. .. 94 70 76 73 78 59 77 80 60 51 61 
12. Strength of grip... .. 79 72 67 55 68 65 75 59 62 45 61 
Mean=.782. 
All round, obviously, the correlations are much smaller in the case 
of the normal children. This indicates that with these the influence of 
the energy has gone down and that of the engines has correspondingly 
gone up. 
N 2 
