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of electrodes (containing the same gel but in opposite hands), the effect or ineffect of gel composition was measured as it affected the frequency and average amplitude of phasic responses. The Unibase prepara- tion was used as a ‘standard’ gel in one set of electrodes. It was found that both the frequency and average amplitude of phasic responses were signifi- cantly lower for the common Unibase preparation than for all other gels except KY Jelly. No other significant correlations could be drawn between gels, although simple gels using only cellulose derivatives fared consistently well. No correlation between phasic re- sponses and NaCl or KC1 as electrolyte was shown.
References 1. Fletcher, James E. (1984) The application of electro- dermal measurement to the evaluation of television advertising. Second International Conference of the International Organization of Psychophysiology. Lon- don. 2. Edelberg, Robert (1967) Electrical properties of the skin. In C.C. Brown (Ed.) Methods in psychophysiol- ogy (pp. 10-11). Baltimore: Williams and Wilkins. 3. Lykken, David T. and Venables, Peter H. (1971) Direct measurement of skin conductance: A proposal for standardization. Psychophysiology 8 (5): 655- 656. 4. Ibid., p. 656.
TRACKING OF SIMPLE RHYTHMICAL MUSIC SEQUENCES BY TAPPING
M. Fran&, T. Radii * and M. Indra * Institute of Theory and History of Art, *Institute of Physiology, Czechoslovak Academy of Sciences, Prague, Czechoslaovakia.
The method of tapping used in presented experiments allows a study of some basic questions of timing in musical context. In order to investigate systematic variations occuring currently in live musical perfor- mance two types of rhythmical stimulation sequences were presented, consisting of (1) regular and (2) non-regular rhythmical patterns. Regular patterns were based on continuously repeated equal temporal inter- vals. Non-regular patterns consisted of intervals of
different duration (ratios 1:0.7, 1:0.8, l:l.l, 1:1.4 were used). The patterns generated by means of a computer were of various complexity, there were 2, 3, 4 and 6 intervals in a pattern. They consisted of accented (long) and unaccented (short) tones of equal pitch, intensity and timbre. Each pattern was repeated many times in a regular way forming the stimulus sequence continued for 2.5 minutes. The subjects (musicians) were asked to synchronize the tapping with the stimulation sequences or to reproduce them.
The main aim was (1) to find out whether such irregularities which exist in live musical performance, will appear in simple acoustic rhythmical structure too and (2) to investigate the abilities of subjects to perform non-regular patterns.
It was found that the subjects performed regular rhythmical patterns with slight irregularity. Although in control pulse sequence subjects deviated randomly from strict regularity, in sequences consisting of pat- terns the systematic deviations were detected. Subjects systematically prolonged certain intervals of pattern and shortened others. The hierarchical structure of timing within the pattern consisting of accented and unaccented elements might be the factor affecting this timing behavior. The musical rhythm is based on hierarchical relationships. Our results demonstrate that the hierarchy is important not only in music but also in much simpler acoustic structures. This fact shows that the principles of hierarchical temporal relationships in musical rhythm are not based on specifically musical perception of time, but on more general rules of time perception and/ or time interval generation.
Although the subjects produced regular patterns with slight irregularity, correct performance of non- regular patterns occured exceptionally. Despite listen- ing constantly to stimulus sequence providing required rhythmical model, one group of subjects altered inter- val ratios of these patterns and assimilated them towards the ratio 1:l and second group transformed these ratios close to 2:l. Our findings in agreement with findings of other authors show that humans prefer certain rhythmical structures. However, the fact that this timing behavior was observed under condition of synchronization suggested that besides of rhythm pref- erence humans are uncapable of generating rhythmical patterns of certain proportions.
