The experiment was devised in further exploration of the effect of the line in ideation. The result fully bears out, when read in the light of the introspective notes, what has been said of the importance of the motor element in ideation. It might have been supposed, in view of the importance usually attached to unity or wholeness of impression in arresting and holding the attention in external perception, that the completed figure would have the more persistent image. The general averages, however, stand as follows: Interrupted lines, 39.32 seconds per minute; completed figure, 29.26 seconds per minute. The individual averages show slight variations from the tendency expressed in these figures, but the averages for the several pairs are all in harmony with the general averages. The notes furnish the key to the situation: "I felt that I was doing more, and had more to do, when thinking of the broken lines." "The broken figure seemed more difficult to get, but to attract attention; continuous figure easy to grasp." "Felt more active when contemplating the image of the broken figure." "In the broken figure I had a feeling of jumping from line to line, and each line seemed to be a separate figure; eye-movement very perceptible." The dominance of the interrupted lines in ideation is evidently connected with the more varied and energetic activity which they excited in the contemplating mind. Apparently the attention cannot be held unless (paradoxical as it may sound) it is kept moving about its object. Hence, a certain degree of complexity in an object is necessary to sustain our interest in it, if we exclude, as we must of course in these experiments, extraneous grounds of interest. Doubtless there are limits to the degree of complexity which we find interesting and which compels attention. A mere confused or disorderly complex, wanting altogether in unity, could hardly be expected to secure attention, if there is any truth in the principle, already recognized, that the definite has in ideation a distinct advantage over the vague. Here again the notes suggest the method of interpretation. "The broken lines," says one, "tended to come together, and to take the form of the continuous figure." Another remarks: "The broken figure suggests a whole connected figure; the continuous is complete, the broken wants to be." In virtue of their power to excite and direct the activity of the attention the interrupted lines seem to have been able to suggest the unity which is wanting in them as they stand. "The broken lines," says another, "seemed to run out and unite, and then to separate again"--a remark which shows a state of brisk and highly suggestive activity in the processes implied in attention to these lines. And a glance at the diagram will show how readily the union of the broken lines may be made. These were arranged symmetrically because the lines of the completed figures were so arranged, in order to equalize as far as