Memory sources of dreams: the incorporation of autobiographical rather than episodic experiences

Abstract

SUMMARYThe present study aimed to explore autobiographical memories (longlasting memories about the self) and episodic memories (memories about discrete episodes or events) within dream content. We adapted earlier episodic memory study paradigms and reinvestigated the incorporation of episodic memory sources into dreams, operationalizing episodic memory as featuring autonoetic consciousness, which is the feeling of truly re-experiencing or reliving a past event. Participants (n = 32) recorded daily diaries and dream diaries, and reported on wake-dream relations for 2 weeks. Using a new scale, dreams were rated for their episodic richness, which categorized memory sources of dreams as being truly episodic (featuring autonoetic consciousness), autobiographical (containing segregated features of experiences that pertained to waking life) or otherwise. Only one dream (0.5%) was found to contain an episodic memory. However, the majority of dreams (>80%) were found to contain low to moderate incorporations of autobiographical memory features. These findings demonstrate the inactivity of intact episodic memories, and emphasize the activity of autobiographical memory and processing within dreams. Taken together, this suggests that memories for personal experiences are experienced fragmentarily and selectively during dreaming, perhaps in order to assimilate these memories into the autobiographical memory schema.

The effect of time of night on wake–dream continuity.

“…These differences in the composition of dreams across the night likely relate to the memory sources of dreams, and as such can be interpreted in light of previous research in this area: for example, that, episodic memory sources are relatively prevalent in NREM dreams and semantic sources in REM dreams (Baylor & Cavallero, 2001; see also Malinowski & Horton, 2014).…”

“…Continuity between waking life and dreams may exist that cannot be highlighted by identification of memory sources, since continuity extends beyond the mere incorporation of episodic memories (Fosse et al, 2003;Malinowski & Horton, 2014). Similarly, elements such as bizarreness and/or discontinuity may change over the night, which may provide insights into continuity.…”

The effect of dream report collection and dream incorporation on memory consolidation during sleep

“…At first glance, memory reactivations might provide an obvious link to dreaming activity (Schredl, 2017;Stickgold, Hobson, Fosse, & Fosse, 2001). The incorporation rate of autobiographical memories in later dreams is relatively high (Malinowski & Horton, 2014;Stickgold, Malia, Maguire, Roddenberry, & O'Connor, M., 2000;Wamsley, Perry, Djonlagic, Reaven, & Stickgold, 2010). Dreaming occurs during both NREM and REM sleep stages, although NREM dreams are less frequent (38%-67% versus 75%-83% in REM), shorter, less emotional and less vivid (McNamara et al, 2010;Montangero, 2018;Stickgold, Paceschott, & Hobson, 1994).…”

Time‐of‐night variations in the story‐like organization of dream experience developed during rapid eye movement sleep

“…The fact that episodic memories, i.e. recent and remote events, are rarely reproduced integrally in reported dreams (in fewer than 2%; Fosse et al ., ; Malinowski and Horton, ) implies that the story‐like structure of dream experience is constructed during sleep. Accordingly, the multi‐level view of dreaming (Foulkes, , ) postulates that the characteristics of story‐like structure reflect the functioning of high‐level cognitive processes involved in dream production, specifically providing for the coherence of dream experience as narrative.…”