1. Problem
It has been shown by many experiments that time and space are closely related to each other in our perception. The psychological dependence of space upon time is a well known phenomenon and Helson (1930) called it the Tau effect. On 1935 two Japanese investigators, Abe M. and Abe S., obtained in their studies the converse of the Tau-effect respectively. The latter called this psychological dependence of time upon space the S-effect. In 1941 Suto Y. clarified that the crucial determinant of apparent time interval was the physical space but the apparent one, exposing three light stimuli in succession at each apex of the Müller-Lyer figure. Recently Abe M. (1948) and the author (1950) confirmed it, using different methods from Suto's in their respective researches.
But up to the present time all investigations on the S-effect have been confined in vision. The present study was designed to investigate the S-effect in tactual space.
2. Method
Three momentary pressure stimuli (B1, B2, and B3) were presented in succession upon the forearms of Ss who kept their eyes closed during experiment. While the spatial distance between B1 and B2(=SN) was kept constant, that between B2 and B3(=Sv) was varied in different series of experiments. Two temporal intervals Ss had to compare were, in general, the following.
Normal time (tN)=BZ1(or BZ2)+PN, and variable time (tV)=BZ2(or BZ3)+Pv, where BZ1, BZ2, and BZ3 are equal resting periods of B1, B2, and B3 upon the skin respectively. PN is the constant pause between B1 and B2, and Pv is the variable pause between B2 and B3. All experiments were done with both orders of B1→B2→B3 and B3→B2→B1
3. Experiments
I Experiments on the S-effect
The purpose of the following experiments was to investigate whether the S-effect took place upon the skin or not. Only a forearm was used. Tables 1-3 show the following facts.
If Sv was longer (shorter) than SN, tV appeared longer (shorter) than tN.
If Sv was equal to SN, tV appeared approximately equal to tN.
So it was confirmed that the S-effect took place upon the skin
II The illusion of tactual space and the temporal perception
The purpose of the following experiments was to see what kind of space was crucial in determining apparent time inteval upon the skin. Both forearms were placed as in Fig. 4. If Ss closed their eyes, B2 B3(=SV) appeared longer than B1 B2(=SN), even though SV was physically shorter than SN. Such a illusion had been shown by Madlung's experiment (1934). Tables 5-7 show the following results:
If physically SV was equal to SN, while apparently SV was longer than SN, then tV appeared longer than tN (Exp. 1).
If physically SV was shorter than SN, while apparently SV was longer than SN, then tV appeared longer than tN (Exp. 3).
If physically SV was shorter than SN, while apparently SV was approximately equal to SN, then tV appeared approximately equal to tN (Exp. 6).
If physically SV was longer than SN, while apparently SV was shorter than SN, then tV appeared shorter than tN (Exp. 7).
These results lead the author to the assumption that apparent time interval does not correspond to the physical space, but to the apparent one. This assumption will be justified by the results of Exps. 8-10.
If physically SV was equal to SN and apparently also SV was approximately equal to SN, tV appeared approximately equal to tN (Exp. 8, cf. Fig. 5).
Since physical distances in Exp. 8 were ecual to those in Exp. 1, and besides, the stimulated loci remained nearly same in both experiments, the discrepancy between both results must be
