The One-Group Apparatus was employed, and cards in general corresponding to those where area was not in question,—white-circle groups equal in size and irregular in inner distribution, which was not duplicated on the same card, though the resulting distribution-error was formally eliminated in the usual way. The usual care was taken to fill the group-area homogeneously. The small-difference cards were retained at first; but on later discovering the possibility of duplication a few supplementary experiments were added.
1. The Influence of Touch.
The apparatus employed to give the touch-stimulus consisted in a long lever attached to the armature of a small electro-magnet. In the end of the lever was inserted at right angles a wooden peg, cork-tipped. In view of the other conditions of the experiment a convenient spot for the application of the stimulus was found to be the forehead where it curves backward above the right eye. The apparatus was supported by rods and clamps upon a long upright steel rod set in an iron base and placed behind the chairs of the observers. The same rod carried a head-rest, designed not as a support but merely to show the observer that he had returned to the original position after he had bent forward to record judgment. Where two observers were used at once two sets of this apparatus were employed, with the magnets in a single circuit governed by a floor-button. The touch-stimulus was made to coincide as closely as possible with the appearance of a given group.
In view of the practical remoteness of this factor from the object of judgment the experimentation here took two forms,—one in which the observer was passive toward the touch-stimulus; the other in which the effort was made closely to associate the touch with the visual group by imagining the group to be responsible for the touch. For the passive method the touch was given irregularly now on the first and now on the last, but as many times on one as on the other.
For the active method, it was given always on the last group. This constancy was held to favor the active association of touch and particular group. The constant time-error was guarded against by experiments in which no modifying factor was introduced. A and B of Table VIII present the results of the passive and active methods respectively. C and D repeat A with duplication of groups,—C with the usual (1/25 sec.), D with a longer, exposure. These last sets were taken that the factor of touch might be studied when the objective conditions of the strong distribution influence should have been removed. It might prove that a factor swamped in the former situation might emerge into effectiveness.
The following summary gathers the chief facts of Table VIII: (1) Touch appears practically without effect in A. (2) In B, the results for touch seem again insignificant; but comparison with the control-results, to isolate touch from time-order, while it shows no marked change for Angier, does show for the others that touch was effective in determining the direction of error by difference-values, in the two cases of 10.2 and 14 per cent. The active method seems to be slightly more favorable to the influence of touch. (3) The duplication of the groups in C gives a large increase to the apparent effectiveness of touch, which is considerably diminished but not destroyed by the lengthening of the exposure in D. (4) The introspection for A indicates that touch under these experimental conditions has little subjective importance for the judgment of number. It is sometimes quite unnoticed. Angier made a possible exception in its favor in cases of great hesitancy where it added "importance" to the group with which it occurred. Usually he felt little doubt. With Shaw the touch was at first distracting but later indifferent. Johnston's notes indicate rather more effect. The touch prevented strict attention to the figure impression whereby the space-intervals in that group lost in value. Later it lost its confusing effect. Here seems to be subjective tendency, but not enough to predominate in results.
TABLE VIII
| A | B | C | D | |||||||||
| 88 experiments with each of two subjects. 132 experiments with one subject. | 198 experiments with each of two subjects. 110 experiments with one subject. | 44 experiments with each subject. | 88 experiments with one subject and 44 with the other Exposure = 1/4 sec. | |||||||||
| Touch | No touch | No tendency | Touch | No touch | No tendency | Touch | No touch | No tendency | Touch | No touch | No tendency | |
| Subjects Av.% of difference | 3 | 3 | 2 | 2 | ||||||||
| in favor of | 3.2 | 5.7 | 26.1 | 13.7 | ||||||||
Results in B for the subjects separately were as follows: Angier 4%, Johnston 8.2%, Shaw 5%, all, so far as they went, in favor of the touch-group. Control experiments to determine the time-error gave the following results: Angier 6.8% in favor of the group last seen, Johnston 2.2%, and Shaw 9% in favor of the first group.
Some further introspective evidence appears in connection with the active method of B. Angier confirms his earlier account exactly. Usually the factors of distribution practically associated with number determine the judgment promptly; but in cases of doubt the touch is felt to add to its group something that appears as number-value. Johnston's subjective situation seems a little complicated. I may summarize thus: (a) The connection between the touch and its group being established, that group seems smaller, as being, together with the touch, somewhere nearly equal to the first. (b) The connection established and touch failing to come, that group seems smaller. (c) The connection not established and attention being concentrated on the visual impression, the touch-group feels much larger. The curious attitude in (a) results in a discounting in advance of the actual number. This done, the touch adds numerical value to its group. In (c) the effort at abstraction appears to emphasize the second (touch) group. Later, he reported similarly that the touch-stimulus seemed to add to the number of circles in its group even when the judgment favored the other group; and that "any outside stimulus connected with the one of two exposures tends to lose its own significance and be translated into number of dots to help the accompanying exposure to equal or exceed the first." The touch-group is felt to have more significance through association with an idea of superior energy or greater motor impulse.