SUMMARY Four dream reports, collected from each of 16 subjects in an experimental night, were analysed using the criteria of Mandler and Johnson's story grammar. The experimental night was the first of the four nights where subjects had spontaneously given a dream report after each of the four awakenings planned in REM sleep. A multivariate analysis of covariance, taking the order of the nights where the experimental night occurred and the order of reports as factors, the number of stories per report as covariate and the number of statements in the setting, the number of statements in the event structure and number of episodes per story as dependent variables, showed that the greater length and complexity of reports collected in the second half of the night depends on a greater effectiveness of the dream production system rather than on a greater accuracy of recall. This increase concerns the organization of individual stories rather than the number of stories developed in a given time. These findings raise the issue of how dream production is re-triggered during REM sleep. To cast light on this issue, it seems important to establish whether and how the themes of the various stories developed in a given dream experience are interrelated. dream experience, mechanisms of dream production, REM sleep, story structure, thematic progression
INTRODUCTIONOn the basis of both theoretical arguments (Foulkes 1982(Foulkes , 1985 and empirical evidence (Cipolli and Poli 1992; Cipolli Psychophysiological investigations on dreaming have shown et al. 1992a), at least three levels of functioning need to be consistently that dream experience, as reported after provoked posited in a model of dream production which can account awakening (mainly in REM sleep), is not only usually for the apparent coherence and complexity of many dreams: perceptually vivid and sometimes bizarre in content, but also (a) Recruitment of information relevant to the ongoing dream organized in a relatively lengthy and coherent narrative of quite experience, given that in almost all dreams various kinds plausible and complex events. Such a prominent characteristic of information (such as episodic memories and semantic suggests that dream experience is the result of a much more knowledge) appear to be processed in generating contents. complex production system than supposed in early studies. As postulated by multilevel models of dream production (for (b) Insertion of contents on a moment-by-moment basis, example, that of Foulkes 1982), the mechanisms supposedly providing for the sequential character of the ongoing operating at a higher level are in principle responsible for the dream. thematic progression of the dream experience, that is for the (c) Hierarchical organization of contents, providing for the organization of its contents into both linearly and hierarchically dream's coherence. ordered sequences of events linked by related characters and settings.A number of insights into the functioning of the mechanisms of the first and second levels ...