12. That of two linear and symmetrical figures, of which one is an outline figure with continuous boundary, and the other consists of the same linear elements, similarly disposed, as the first, but has its lines disconnected so that it has no continuous boundary, the latter figure has the advantage in ideation. 13. That if, with material similar to that described in paragraph 12, the disconnected lines are arranged so as to be vertical and equidistant, the advantage in ideation still remains with the disconnected lines, but is much reduced. 14. That if one of two figures, of similar appearance and form and of equal dimensions, is kept in motion while it is exposed to view, and the other is left at rest, the image of the moving object is the more persistent. 15. That, under like conditions, colored objects are more persistent in ideation than gray objects. 16. That lines and sharp angles, as compared with broad surfaces, have a strong directive force in the determination of the attention to their images or ideas; that this directive force is strongest in the case of very acute angles, the attention being carried forward in the direction indicated by the apex of the angle; but that uncompleted lines, especially when two such lines are directed towards each other, have a similar and not much inferior force in the control of the course of ideation. If we should seek now to generalize these experimental results, they would take some such form as the following: Abstraction made of all volitional aims and all æsthetic or affective bias, the tendency of an object to recur and persist in idea depends (within the limits imposed by the conditions of these experiments) upon the extent of its surface, the complexity of its form, the diversity of its contents, the length and recency of the time during which it occupies the attention, the definiteness of the direction which it imparts to the attention (as in the case of angles and lines), its state of motion or of rest, and, finally, its brightness and its color.