Addendum: New Studies of Sleep-Talking (Heynick, 1980a, b)
While the present volume was in the process of final editing, two new articles on somniloquy written by F. Heynick ( 1980a, 1980b) came to my attention. Space limitations permit me to write only of the highlights of his work and the reader is referred to the original papers for details when they appear.
Heynick ( 1980a, 1980b) based his paper on 86 sleep talking episodes uttered by 15 native Dutch-speaking subjects sleeping at home. They were all unpaid volunteers chosen from over 150 people responding to radio and newspaper advertisements for "chronic sleep-talkers." They ranged in age from 12-83; 10 were female and 5 male. The research was carried out under the auspices of the Technische Hogeschool of Eindhoven in The Netherlands. No indication was given regarding the total population reached by the advertisements, nor the total geographic area surveyed, so we cannot use the data to hazard quantitative estimates about the prevalence of sleep-talking. The data do suggest, however, in conformity with findings described earlier in the book, that sleep-talking is indeed common.
Electro-encephalographic monitoring was not feasible. Subjects were supplied with cassette-tape recorders equipped with a voice-triggered microphone. About 2 weeks after home recording, subjects were asked, while awake, a series of 25 questions about their verbalizations. Heynick sought to compare sleep-speech with wakeful speech along a number of psycholinguistic dimensions, and to elicit subjects' comments about aspects of their somniloquy.