Incidence of Threat in Dreams: A Response to Revonsuo's Threat Simulation Theory.

Abstract

A. Revonsuo (2000b) proposed an evolutionary theory of dreaming, stating it is a threat simulation mechanism that allowed early humans to rehearse threat perception and avoidance without biological cost. The present study aimed to establish the proportion of dreams containing physical threats to the dreamer, whether these represent realistic life-threatening events, and whether the dreamer successfully and realistically escapes. It also examined incidence of threatening events in real life. A sample of most recent dreams was collected (N = 401). Only 8.48% of dreamers reported realistic life-threatening events in dreams and a realistic escape subsequently occurred in only one third of these reports. Actual severe life-threatening events were experienced by 44.58% of the sample. These findings contradict key aspect so f Revonsuo’s theory. The authoritative journal Behavioral and Brain Sciences recently published a special edition containing new theories and extensive peer commentary on the nature and function of sleep and dreaming. Among the theories advanced was Revonsuo’s (2000b) threat simulation theory (TST). This theory postulates that dreaming serves the biological function of enhancing perception and avoidance of real-life threats, thus bestowing an adaptive advantage. TST is expressed in six propositions. Proposition 1 states that dream content is not random or disorganized but is a simulation of the perceptual world. Proposition 2 states that dream consciousness is specialized for simulating threatening events. From this, Revonsuo (2000b) made three predictions: First, if we define a category containing all threats, these threats will be overrepresented in dreams; second, severe or mortally dangerous threatening events will be included in dreams more frequently than in waking life; and third, if triggered by real events, the threat simulation mechanism should generate rehearsals of ancestral threats (e.g., animal attacks, direct physical aggression) more easily than modern threats (e.g., traffic accidents, explosives). Proposition 3 states that exposure to real threatening events activates the threat simulation mechanism. Proposition 4 states that the threat simulations produced by the fully