抄録
It was reported in the previous paper that pressure on the skin lowers the sensitivity of pressure sensation in another area. In this paper, the author reports a peculiar fact revealed by successive measurements of pressure sensitivity with and without skin pressure alternately.
The sensitivity was measured by the number of pressure spots within a given area of the dorsal side of the right forearm, and the conditioning pressure was given on the forearm, proximally to the test area. A measurement group consists of a pair of sensitivity measurements: such as M1·M2, pM1·pM2, M1·pM2 and pM1·M2 (see Table 1: Abbreviations). Each pair of measurements is made at the interval of 5 min. in series (Table 2).
The results were as follows:-
1) M1·M2 series showed almost steady sensitivity (Table 3 & Fig. 1).
2) pM1·pM2 series showed the decrease of sensitivity to 20-30% of the normal value. After the release of pressure, the sensitivity recovered gradually to the normal value within about 90min. (Table 4 & Fig. 2).
3) In M1·pM2 series (conditioned series), the sensitivity was nearly normal in M1, but in pM2 it lowered to 20-30% of M1. Consequently, in this experiment, each group showed a pair of high and low sensitivities. When M1·M2 series (as a test series) was given after this, the decreasing effect remained only in M2, and this after-effect gradually disappeared within about 90min. (Table 5 & Fig. 3). So in this case, the sensitivity pattern formed in M1·M2 group after M1·pM2 series is a pair of high and low ones. It may be said that the after-effect takes place as a group-pattern of high-low.
4) It seemed that the duration of the after-effect on M1·M2 was proportional to the number of conditioned group of M1·pM2 series (Fig. in note).
5) If no test series was given after M1·pM2 series, the after-effect as group-pattern disappeared earlier than in the case in which M1·M2 series followed.
6) When the single sensitivity measurement (M) was made after M1·pM2 series, the after-effect as group-pattern could not be recognized (Fig. 4). And when the test group and the conditioned group took the same interval, the after-effect had the maximum value (Fig. 5).
7) The after-effect as group-pattern could be extinguished by the reversal combination (pM1·M2) of conditioned pattern, and various stimuli such as touch, sound, light, etc. (Fig. 6).
8) If the pM1·M2 series followed M1·M2 series, the sensitivity decreased to 30% in pM1, and 60-80% in M2. Then the after-effect was found, not as the group-pattern of low-high but as the simple decrease (Fig. 7).
9) To form the after-effect as group-pattern, the pattern in the preceding conditioned series must have clear contrast of high and low.
The phenomenon described as “the after-effect as group-pattern” would be considered as a conditioned response, in which the unconditioned stimulus is a pressure on the skin, and the conditioned stimulus is the situation of the pressure in the conditioned group. For there are reinforcement and extinction of the response, and generalization of unconditioned stimulus and quasi-secondary reinforcement are also found.
It may be considered that this conditioned response is formed in some level of the central nervous system with spatial extension.
