In Opposite Directions.
Subj.L.-R.Ret.R.-L.Ret.U.-D.Ret.D.-U.Ret.
B.1.82 2.90 2.10 2.27
0.86 0.87 0.73 0.86
G.3.02 2.86 2.68 2.63
1.98 2.25 1.63 2.01
H.9.18 10.30 7.50 7.15
5.16 6.90 5.36 5.21
I. 4.17 3.52 3.40 3.37
1.26 1.47 1.23 1.31
J.2.17 2.90 2.87 2.27
1.05 1.63 1.02 1.13
K.5.51 6.43 5.16 4.81
1.43 1.48 1.20 1.23
Ave.4.32 4.82 3.82 3.75
1.96 2.43 1.87 1.96

Average of all movements involving separation (480), 4.18. Returns, 2.06.

In Same Direction.
Subj.R.Ret.L.Ret.U.Ret.D.Ret.
B.1.31 1.22 1.30 1.11
0.72 0.67 0.72 0.85
G.2.66 2.35 3.01 2.53
2.00 1.86 2.22 1.86
H.8.45 7.91 5.66 7.66
6.53 5.95 5.96 6.11
I. 2.57 2.27 2.13 2.05
0.97 1.26 1.00 1.13
J.1.11 1.16 1.08 11.5
0.68 0.90 0.73 0.71
K.3.97 3.91 3.60 4.07
1.35 1.50 1.75 1.71
Ave.3.33 3.14 2.79 3.10
2.04 2.02 2.04 2.06

Average of all movements together (480), 3.09. Returns, 2.04.

NUMERICAL.

There were nineteen hundred and twenty movements in all, including the returns to the original positions.

In the order of difficulty as shown by the time taken, the movements stand as follows, the numbers being the averages in seconds for one hundred and twenty movements of each kind:

1. Right and left (i.e., crossing),4.82sec.
2. Left and right,4.32"
3. Up and down,3.82"
4. Down and up,3.75"
5. Both right,3.33"
6. Both left,3.14"
7. Both down,3.10"
8. Both up,3.04"

SUBJECTIVE.

In the experiments in which the time was recorded, there was no disappearance of either image except where movements were made successively. In these cases frequently the image which was awaiting its turn vanished until the first image was placed, a time varying from a quarter of a second to three or four seconds. Occasionally the image already placed would vanish, while the other was en route; the subject's attention in both these cases being centered exclusively on the image he desired to move. This was especially the case when the distances to which the images were moved were great, as to the ends of the room or to ceiling and floor. In other experiments, where, after the movements took place, the images were held for a short time, there were disappearances of one image or the other ranging from one quarter of a second to fifteen seconds, most of the absences, however, being under five seconds. The absences were more numerous in the latter half of the five minutes covered by the experiment. Occasionally a noise in the adjoining room or in the street made the images disappear.