From the above discussion it must be evident that one of the chief characteristics of free attention is its unity. The mental activity of the person is all directed along one line, that which leads to the satisfying of the need. It is unified by the appeal the situation makes. As a result of such a state the attention is likely to be concentrated, and can be sustained over a long period. Of course this means that the work accomplished under such conditions will be greater in amount, more thorough, and more accurate than could be true were there less unity in the process. The opposite in all respects is true of forced attention. It is present when there is divided interest. The topic does not appeal to the need of the individual. He attends to it because he must. Part of his full power of attention is given to keeping himself to the work, leaving only a part to be given to the work itself. If there is any other object in the field of attention which is particularly attractive, as there usually is, that claims its share, and the attention is still further divided. Divided attention cannot be concentrated; it cannot last long. The very strain and effort involved makes it extremely fatiguing. The results of work done under such conditions must be poor. There can be but little thoroughness, for the worker will do just as much as he must to pass muster, and no more. Inaccuracy and superficiality will characterize such work. Just as training in giving concentrated attention results in power along that line, so frequent necessity for forced attention develops habits of divided attention which in time will hinder the development of any concentration.