Such doubts, which are known to all investigators, led us to decide to make direct observations on our own account upon abnormal school-children, and to compare them with normal children of the same age—a long and difficult task, as all pioneer work is. We have collected facts which we were not seeking, whilst we often failed to find what we expected. It would be impossible to summarise here everything which contact with reality has taught and suggested. We shall extract from our observations only what concerns the aptitudes of the abnormal, and shall even limit ourselves to a single category of these. It happens that we have methodical observations relating to twelve defective children of between eleven and twelve years of age. These form a sufficiently homogeneous group from the point of view both of age and of mental ability. We shall inquire what are the best marked aptitudes and the most apparent deficiencies of this little group. Without denying individual differences or forgetting that defectives cannot easily be reduced to a single type, we have thought it more interesting for the present to emphasise their resemblances rather than their differences. Let us, then, compare them en bloc with a group of normal children of the same age and the same social position, attending the same schools, in the same district. This equivalence of conditions is necessary if we are to lay our finger on the distinctive characters of the defective child.
We have subjected our twelve defectives to certain tests as speedy and precise as possible.[3] We devised these tests before studying the returns furnished to our questionnaires, and the latter were tabulated before our observations. There have, therefore, been two studies absolutely independent, both in their mode of execution, and in their aim. Consequently, any points in which they agree will be very significant.
Our collection of tests of mental deficiency is already known to readers of the Année Psychologique.[4] In vol. xi. we described at length the details necessary for making use of our method of experimentation. Since then Dr. Decroly, who specialises on defective children in Belgium, has tried our methods, and verified our conclusions. The end which we have constantly set before ourselves has been to bring to light the intellectual capacity of the child, taken by itself, as distinct from what the child actually knows. Our psychological examinations are consequently the very opposite of school examinations, which test chiefly the candidate's memory, his judgment very little.
We have made numerous observations in this way. The best way to explain our method, and more especially our results, will be to describe a few of the experiments.
Memory of Pictures of Known Objects.—The children are allowed to look for thirty seconds at pictures of thirteen objects, which they are then told to enumerate from memory.
Comparison of Short Lines.—Two lines for comparison are drawn in ink side by side on the same sheet of paper, so that they can both be seen at a glance. We have a whole series of such pairs. Between the lines, whose average length is 30 millimetres, there is a variable difference.
Estimation of Weights.—Five little boxes, weighing respectively 3, 6, 9, 12, and 15 grammes, are to be arranged in order of weight.
Memory of Figures.—This test consists in repeating a series of figures immediately after having heard them.
Memory of Phrases.—The child is asked to repeat a phrase of twelve to fifteen words immediately after having heard it.
We do not wish to insist on the details of these observations. They are still very incomplete. It will be necessary to experiment for a long time[5] before it will be possible to say exactly what it is that is wanting, or that is wrong, in the mental machinery of the defective. No doubt when the classes for defectives shall be under way, when a great many such children are brought together in conditions which suit the convenience of the experimenters, the latter will be able after persevering effort to see daylight in this matter. In the meantime we must be content with a general survey. But however superficial, however defective, our first attempts may be, they may at least give us a start.