Involuntary movements are not limited to the horizontal plane; vertical movements may be recorded by holding the recording device in a slanting position, and fixing the record plate upon the wall. The main characteristic of such a record is the sinking of the arm through fatigue; the movement is rapid and coarse (tracing I. of Fig. 20). If the attention be directed to the front, we obtain a resultant of the tendency to move towards the object of attention, and of the sinking of the arm, as appears in the diagonal line of Fig. 22. Fig. 21 illustrates an interesting point similar to that illustrated in Fig. 14. When the attention is directed downward, the hand falls rapidly (tracing I.); but when the attention is directed upward, very little movement at all takes place,—the tendency to move towards the object of attention constantly counteracting the tendency for the arm to fall (tracing II.).
Fig. 22.—Counting the strokes of a metronome. Record plate vertical. Pencil held in extended right hand. Time of record, 20 seconds. Direction of the attention ←. Subject facing ←.
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While I have not been altogether successful in determining by this method the relative efficiency of different sense-impressions in holding the attention, the successful results are especially interesting. In Fig. 23 the tracing marked I. shows the movement of the hand during the thirty-five seconds that the subject was counting the strokes of a metronome; tracing II. shows the movement while counting for twenty-five seconds the oscillations of a pendulum. The latter movement is in this case much more extensive than the former, thus indicating that the visual impression held the attention much better than the auditory. The subject of this record is a well-known writer and novelist; and his description of his own mental processes entirely accords with this result; he is a good visualizer, and visual impressions and memory-images dominate his mental habits.
Fig. 23.—I. Counting the strokes of a metronome. Automatograph record. Time of record, 35 seconds. Direction of the attention →. Subject facing →. II. Counting pendulum oscillations. Automatograph record. Time of record, 25 seconds. Direction of the attention →. Subject facing →.
Fig. 24.—From A to A´, reading colors; from A´ on, counting pendulum oscillations. Automatograph record. Time of record, from A to A´, 35 seconds; from A´ on, 25 seconds. Direction of the attention→. Subject facing →.
We may next turn to Fig. 24. The subject was asked to call the names of a series of small patches of color hanging upon the wall in front of him. He did this with some uncertainty for thirty-five seconds, and during this time his hand on the automatograph moved from A to A´. At the latter point he was asked to count the oscillations of a pendulum; this entirely changed the movement, the hand at once moving rapidly toward the pendulum. The pendulum was a more attractive sense-impression than the colors. The special point of interest in this record is, that upon examination the subject's color-vision proved to be defective, and thus accounted for the failure of the colors to hold his attention.