Experimental Studies on Galvanic Skin Response

Abstract

One of the most outstanding characteristics of GSR is adaptation, or diminution of the response upon repeated stimulation. There are, it must be added certain experimental designs in which the investigators are obliged to administer a stimulus repeatedly to make their investigations. Therefore the investigators who utilize GSR for any purpose and very often required to take into their consideration the effect of repeated stimulation upon the response. The present studies were undertaken to investigate some aspects of this fact and divided into two parts:
1) Selection of the appropriate unit for use in the measurement of GSP, especially in the situation where repeated stimulation is employed.
The investigation ig the appropriate unit was most recently undertaken by Lacey, Haggard et al., who successfully selected conductance as the most proper unit-the same conclusion reached in the physiological observation by Darrow some ten years ago, but those researches did not cover the occasion above mentioned. Then our problem is to examine whether the unit selected by Lecey et al. and other conceivable units can be adopted in our case.
The raw data were obtained by giving each subject a loud noise ten times and then converted to several sorts of the conceivable units including conductance proposed by Lecey et al. The results lead to the following conclusion. As for the basal level, conductance is the most desirable unit from the viewpoint of normality of distribution (Table 1). As for GSR, change in conductance, % change in conductance and % change in resistance are the most acceptable units in view of both normality of distribution and independence of the basal level (Table 1, Table 2).
2) Analysis of the nature of GSR's diminution.
A slight observation could make clear that diminution of the response has many aspects. First, individual differences may attract observers' attention. Another aspect is that the variabilities of the response are partiallu due to the kind of stimulus used. For example, if an investigator employed a series of words as stimuli, he would easily be convinced that every word has a different effect upon the response of his subjects. Moreover, if he changed the position of words in the series, he might observe that the changed position produces a different response. Thus diminution of GSR is complicated by many factors en bloc, among which these three are perhaps the most important ones.
To analyse the nature of diminution, then, experimental designs in statistics are required. Our investigation in this part was to ascertain this fact statistically in hope of marking a step to make further progress on the studies of GSR and included two experiments, of which each was undertaken in different design.
In one experiment, each subject was given a loud noise twelve times individually and the data obtained were analysed by Randomized Block Experiment (Table 4). The result shows that difference for diminution and for individuals are also significant.
In another, each subject was given a series of twelve words selected from Japanese vocabulary as comparatively indifferent ones and randomized in their position. The data obtaind were analysed by Latin Square Design (Table 6). It can be concluded then that differences for stimuli, for individuals and for position are also significant.