Replication of the Day-residue and Dream-lag Effect
Geneviève Alain, M.Ps.
Geneviève Alain completed her Bachelor and Master’s degree in psychology at Laval University in Quebec City. She is currently doing her Ph.D. program in psychology at the University of Montreal under the direction of Tore Nielsen, Ph.D. Her principal interests are dreams and personality, therapy with dreams, and nightmares in relation with PTSD.
Tore A. Nielsen, Ph.D.
Russell Powell, Ph.D.
Don Kuiken, Ph.D.
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Summary of Presentation
The present study is an attempt to replicate prior demonstrations of the
day-residue and dream-lag effects, which describe temporal factors in the
incorporation of daily events into dreams. Results from a between-subjects
design clearly support the existence of these two effects. Implications for
memory and adaptation to stressful events are discussed.
Introduction: The temporal relationship between daily events and dream incorporation seems to be defined by two types of effects: the day-residue effect, which refers to the incorporation into dreams of material from the immediately preceding day, and the dream-lag effect, which corresponds to the incorporation into dreams of daytime experiences occurring approximately one week prior to the dream. Previous studies demonstrating the dream-lag effect (1-4) involved some methodological problems and justified a replication of the phenomenon using a strategy allowing for memory limitations and for control of biases implied in repetitive tasks.
Methods: Four hundred and seventy students from Introductory Psychology classes were asked to keep written records of their dreams for a one-week period. They were then asked to select from their diary the most recent dream that they could remember well. To prevent subjects from discovering the study’s purpose, they were required to recall events that occurred on a specific day prior to the dream that was randomly determined by the experimenter. Considering that poor memory can affect incorporation ratings, subjects who indicated that they couldn’t remember well events from the specific day were excluded. Among the 212 remaining subjects (X=19.6 ± 2.10 years), 74.5% were female, 20.8% male and 4.7% unspecified. In total, fifty participants were assigned to day 1, 38 to day 2, 26 to day 3, 25 to day 4, 27 to day 5, 26 to day 6 and 20 to day 7. To measure the incorporation of daily events into dreams, students were asked to identify on a 10-point Likert scale the degree of correspondence between the most noticeable event from the specific day and the dream selected. Incorporation scores were entered into an ANOVA with number of days prior to the dream as a between groups independent factor. A U-shaped (quadratic) curve was predicted as were mean incorporation differences between Days 1-2 (Day-residue group), Days 3-4 (Control group) and Days 5-6-7 (Dream-lag group).
Results: As predicted, a significant main effect for day prior to dream was obtained (F(6,205)=2.228; p=0.042) (Figure 1). Of the two polynomial trends tested (linear, quadratic), only the quadratic was significant (F(1,205)=10.273; p=0.002). Comparisons between the three groups (Day-residue, Control, Dream-lag) revealed a significant difference between means (F(2,209)=4.412; p=0.013) with post-hoc analyses demonstrating differences (p<0.05) between the Day-residue and Control groups as well as between the Dream-lag and Control groups. The Day-residue and Dream-lag groups did not differ.
Conclusions: The results replicate the U-shaped pattern of incorporations of daytime experiences into dreams found in at least 4 previous studies (1-3). Causes of the day-residue and dream-lag effects remain unknown, although an influence from memory functions has been proposed (3,4) as has a process of adaptation to stressful events (5). Specifically, it may be that the U-shaped curve reflects: a) storage of new memories in the hippocampus (day-residue) followed by transfer from hippocampus to other brain networks (dream-lag effect), and/or b) an alternation of periods of coping dreams (day-residue and dream-lag dreams) and avoidance dreams (Day 3-4 dreams) in response to stressful events.
This research was supported by the Canadian Institutes of Health Research (CIHR) and the Fonds de la recherche en santé du Québec (FRSQ).
Alan Siegel, Ph.D.
Program Committee: Mark Blagrove, Ph.D.; Kelly Bulkeley, Ph.D.; Rita Dwyer; Nancy Grace, M.A.; Roger Knudson, Ph.D.; Richard Russo, M.A.; Richard Wilkerson; Lilith Wolinsky; Dave Pleasants
Conference Co-Hosts: Nancy Lund, M.A.; Steven Smith, M.B.A.; M.A.; Bob Hoss, M.S.
Host Committee :Marilyn Fowler (Volunteer Coordinator); Emily Anderson