P. SUBJECT W. SUBJECT B.
(1)—(3) (3)—(4) (1)—(3) (3)—(5) (2)—(1) (6)—(2) (2)—(1)
First. + — + — — + — Sec. + + — + + + +
The comparisons of (6) and (2), and (1) and (3) confirm the provisional deduction from Table IV., that the introduction of a local change in an interval lengthens it subjectively, but the comparisons of (3) and (5), (3) and (4), and (2) and (1) show apparently that while the amount of the local change influences the lengthening of the interval, it does not vary directly with this latter in all cases, but inversely in the first interval and directly in the second. This is in itself sufficient to demonstrate that the chief factors of the influence of locality-change upon the time interval are connected with the spatial localization of the areas stimulated, but a further consideration strengthens the conclusion and disposes of the apparent anomaly. It will be noticed that in general the decrease in the comparative length of the first interval produced by increasing the spatial change is less than the increase in the comparative length of the second interval produced by a corresponding change. In other words, the disparity between the results for the two types of test is greater, the greater the spatial distance introduced.
The results seem to point to the existence of two distinct factors in the so-called ‘constant error’ in these cases: first, what we may call the bare constant error, or simply the constant error, which appears when the conditions of stimulation are objectively the same as regards both intervals, and which we must suppose to be present in all other cases; and second, the particular lengthening effect which a change in locality produces upon the interval in which it occurs. These two factors may work in conjunction or in opposition, according to conditions. The bare constant error does not remain exactly the same at all times for any individual and is probably less regular in tactual time than in auditory or in optical time, according to the irregularity actually found and for reasons which will be assigned later.
3. The third group of experiments introduced the factor of variation in intensity of stimulation. By the introduction of a loop in the circuit, containing a rheostat, two strengths of current and consequently of stimulus intensity were obtained, either of which could be employed as desired. One intensity, designated as W, was just strong enough to be perceived distinctly. The other intensity, designated as S, was somewhat stronger than the intensity used in the preceding work.
In the first instance, sixty series were taken from Subject B, with the conditions the same as in the experiments of Group 1, except that two types of series were taken; the first two stimulations being strong and the third one weak in the first type (SSW), and the order being reversed in the second type (WSS). The results gave values of ET of 5.27 secs. for SSW and 5.9 secs. for WSS.