"After carefully observing the service in the central office for a while, I came to the conviction that it would not be appropriate here to reproduce the activity at the switchboard in the experiment, but that it would be more desirable to resolve that whole function into its elements and to undertake the experimental test of a whole series of elementary mental dispositions. Every one of these mental acts can then be examined according to well-known laboratory methods without giving to the experiments any direct relation to the characteristic telephone operation as such. I carried on the first series of experiments with about thirty young women who a short time before had entered into the telephone training-school, where they are admitted only at the age between seventeen and twenty-three years. I examined them with reference to eight different psychological functions. * * * A part of the psychological tests were carried on in individual examinations, but the greater part with the whole class together. [Sidenote: _Memory Test_] [Sidenote: _Test for Attention_] "These common tests referred to memory, attention, intelligence, exactitude and rapidity. I may characterize the experiments in a few words. The memory examination consisted of reading the whole class at first two numbers of four digits, then two of five digits, then two of six digits, and so on up to figures of twelve digits, and demanding that they be written down as soon as a signal was given. The experiments on attention, which in this case of the telephone operators seemed to me especially significant, made use of a method the principle of which has frequently been applied in the experimental psychology of individual differences, and which I adjusted to our special needs. The requirement is to cross out a particular letter in a connected text. Every one of the thirty women in the classroom received the same first page of a newspaper of that morning. I emphasize that it was a new paper, as the newness of the content was to secure the desired distraction of the attention. As soon as the signal was given, each one of the girls had to cross out with a pencil every 'a' in the text for six minutes. After a certain time, a bell signal was given, and each then had to begin a new column. In this way we could find out, first, how many letters were correctly crossed out in those six minutes; secondly, how many letters were overlooked; and thirdly, how the recognition and the oversight were distributed in the various parts of the text. In every one of these three directions strong individual differences were indeed noticeable. Some persons crossed out many, but also overlooked many; others overlooked hardly any of the 'a's,' but proceeded very slowly, so that the total number of the crossed-out letters was small. Moreover, it was found that some at first do poor work, but soon reach a point at which their attention remains on a high level; others begin with a relatively high