Concentration of the attention on the image to be retained and an ignoring of the other was, on the whole, the method usually and successfully followed.  This concentration was helped by imagining the image marked off into minute squares which were carefully counted.  Numerous other devices of a similar character were used.  Objects having many details and those lending themselves readily to suggestions of action (as a china animal) were the most helpful in enabling the subject to concentrate his attention on their image to the exclusion of another.  Some subjects conceived themselves as tracing with a pencil the outline and details of the retained image.  Frequently, when the two images were originally near each other and one alone was being held by close scrutiny of its parts, when this scrutiny reached the part of the image which was nearest the position of the suppressed image, the suppressed image returned.  The original association between the two images was often broken up by change of the position or shape of the one to be suppressed.  But devices soon became ‘worn out’ and new ones had to be resorted to.

Motor impulses played a large part in the process of suppression, such as head and eye movement away from the image to be suppressed, contraction of the muscles of the forehead and scalp, occasional ‘setting’ of the teeth, pressure together of the hands when they were supposed to be holding the image and of the knees under like circumstances.  The eye traced outline and details and the more actively it could be so employed the more successful was the suppression.  The sensations of accommodation and of focusing previously referred to were repeated in this series.  Enunciation also was very common.

Frequent comparison of the image with the percept was made at the close of experiments and showed the utmost diversity in size, vividness and distinctness.  During an experiment when the suppressed image came back, it was rarely more than a mere blur of color; in two or three instances the form came without color.  Green was found to be a difficult color to hold.  C. had an orange after-image from a retained yellow image, a red image having been suppressed.  Between the images of a gray disc and an orange disc, three inches apart, he had a blue disc.  J., while suppressing an orange disc and retaining a green disc, noticed that ’when off the fovea the whole green disc became bright orange.’  There was always a sense of readiness on the part of the suppressed image to slip back.  As C. expressed this, “The thing suppressed exists in the fringe of consciousness.”  The recurring image usually came back at its original position even when the retained image was being held in a different part of the field.  In such cases the retained image at once resumed its original place.

G. and J. were successful in proportion as they freed themselves from the nervous strain of anxiety as to the result.

V. MOVEMENTS OF A SINGLE IMAGE, THE OBJECT HAVING BEEN MOVED DURING THE EXPOSURE.