Dreaming not only places us into an immersive (virtual) physical reality, but also immerses us into a (virtual) social reality: in dreams we are surrounded by close friends and family members, schoolmates, teachers and students, spouses, romantic partners, old crushes, colleagues and bosses, celebrities, politicians, acquaintances, strangers, and mobs as well as monsters and other fictitious characters from movies and video games. All are there in dream simulation with us as simulated characters—avatars—and we interact with these avatars in multiple ways: we perceive, recognize, and semantically classify them, we communicate and talk with them, we collaborate with them, help them, criticize them, fight them, escape them, fear them, and love them. At least intuitively, there is no doubt that in our dreams, we live rich and colourful social lives, even if only simulated ones.
If dreaming in general can be defined as a simulated world, the question arises whether the concept of “simulation” can also be usefully applied to describe the social reality of dreams. The first task for a theory that takes the concept of simulation seriously is to simply describe the social contents of dreams as simulations of human social reality. The descriptive questions can be formulated in more detail along the following lines:
What kind of social perception, social interaction, and social behaviours are simulated in dreams?
How frequently are different kinds of social perception, interaction, and behaviour simulated in dreams? How much variation is there in the frequency of different social simulations as a function of gender, age, culture, and as a function of the quality and quantity of social interactions during waking life?
It is possible to find answers to many of the above descriptive questions from the already-existing dream research literature where various aspects of the social contents of dreams have been reported, even if they have not been conceptualized as social simulations. In what follows, we will first briefly review some of the major findings in the literature that describe the quality and the quantity of social simulation in dreams. Once we have detailed empirical descriptions of the quality and quantity of social simulations in dreams, we may seek explanatory theories and testable hypotheses that could account for why we have social simulation in dreams.
From the already existing literature, it is possible to find statistics that describe the quality and quantity of social simulations in dreams. However, the theoretical concept of “social simulation” is rarely used in dream research literature for interpreting the descriptive results. Here, we will briefly summarize only some of the major findings.
The minimal criterion for a dream to count as a social simulation is that the Dream Self is not alone in the dream but in the presence of at least some other animate character or characters. In less than 5% of dreams is the dreamer alone (Domhoff 1996); thus, on this minimal criterion, dreaming seems to consistently simulate social reality. The other animate characters simulated in dreams are predominantly human (normative finding in adults is about 95% human, 5% animal), but the proportion of animal characters varies in different cultures and age groups, being highest (up to 30–40%) in young children and in adults in hunter-gatherer societies (Domhoff 1996; Revonsuo 2000). As human characters are reported in almost all dreams, and typically there are two to four non-self characters in a dream (Nielsen & Lara-Carrasco 2007), the presence of simulated human characters must be perceptually detected and registered in the dream by the dreamer. Thus, during dreaming, our neurocognitive mechanisms constantly simulate social perception.
The minimal form of social perception is to detect or register the presence of some human character. A more sophisticated form is the perceptual recognition and identification of the human characters who are present, first in terms of some basic perceptual and semantic categories (male/female; familiar/stranger), and then in terms of more detailed semantic and autobiographical information about the precise identity and name of the person. According to the Hall and Van de Castle norms, about 90% of simulated human characters have sufficiently definite characteristics to be semantically categorized, for example as male or female, or as familiar or unfamiliar (Domhoff 1996). Thus, social recognition and identification mechanisms are highly engaged in almost all cases of social perception in dreams. The dreamer knows, both during the dream and afterwards when reporting it, whether the simulated characters present in the dream are (or were) male or female, familiar or strange, friend or family; and in most cases, the familiar characters are identified as particular persons from real life.
Typically, a slight majority of dream characters are avatars for familiar persons, although there are well-established gender differences (Domhoff 1996) that might, however, partly depend on the gender distribution encountered in the real-world social environment (Paul & Schredl 2012). In a sample of five hundred REM dreams (Strauch & Meier 1996) familiar people (friends, acquaintances, and relatives) were simulated most frequently (44% of all characters), strangers represented about 25% of dream characters, and undefined people about 19%. In most dreams, both familiar and unfamiliar people were simulated, but in 30% only strangers and in 20% only familiar people appeared. The mixture of familiar and unfamiliar people was true also at the individual level—there were no participants who would have simulated only strangers or only familiar people in their dreams.
For the most part, the human avatars in the dream world are quite realistic simulations of their waking counterparts. The degree of realism, however, is difficult to express with accuracy by any single measure or quantity, as there are several features of human characters that may independently vary along the dimension of realism (Revonsuo & Tarkko 2002). The opposite pole for realism is called bizarreness, which in dream research refers to deviation from the corresponding entity in waking life.
If any kind and degree of deviation from a waking counterpart is counted as a bizarre feature of a simulated person, then over half of the simulated humans in dreams (over 60% according to Kahn et al. 2002; 53% according to Revonsuo & Tarkko 2002) are not perfectly realistic simulations. In contrast to other dream characters the Dream Self is rarely distorted in any way (Revonsuo & Salmivalli 1995). Revonsuo & Tarkko (2002) also found that in the vast majority of cases (around 90% of dream characters), non-self dream characters are perceptually entirely realistic—they look the same as their counterparts look in real life. Where they deviate from their counterparts is most often their verbal and nonverbal behaviour. Thus, although the perceptual simulation of human characters is nearly flawless in dreams, the simulation of expected or predicted behaviours deviate from waking norms relatively often, though still at least a slight majority of behaviours by dream characters are no different from waking life.
Dream characters are also spatially and temporally quite stable and continuous within the dream, although transformations and discontinuities sometimes do happen (Nielsen & Lara-Carrasco 2007). A simulated person sometimes appears from nowhere, is magically transformed into someone else, or suddenly disappears without a trace. But these kind of discontinuous features account for less than 5% of dream character features (Revonsuo & Salmivalli 1995; see also Revonsuo & Tarkko 2002).
By contrast, the behaviours expressed by dream characters are relatively often to some extent odd or unpredictable. Thus, the simulated social reality in dreams is less predictable than the corresponding social reality during wakefulness. However, it is unclear how this unpredictability should be interpreted: does it simply reflect the difficulty (and consequently failure) of simulating complex human behaviours and interactions realistically by the dreaming brain, or is there some other more functional explanation as to why the avatars in our dreams tend to behave in more erratic ways compared to their waking-life counterparts? We will come back to this question when we consider the possible functions of social simulation in dreams.
The Dream Self and other dream characters are simulated in almost all dreams, but how often are they engaged in mutual social interactions? According to Strauch & Meier’s (1996) data (140 REM dreams in which a Dream Self was present and had an active role), in nearly 50% of these dreams the Dream Self and characters interacted, in an additional 20% they acted together, and in 20% they acted independently of each other. In the rest, the Dream Self acted alone. Thus, social interaction or acting together is typically simulated in dreams where the Dream Self is present together with some other dream characters. When social interaction takes place, there is almost always verbal communication or conversation between the Dream Self and the other characters, which tends to be focused on concrete topics (Strauch & Meier 1996), and it is understandable and something that would be sayable in waking life (Heynick 1993).
The more detailed nature of social interactions has typically been categorized in terms of “friendly” and “aggressive” interactions. Friendly interactions are on average found in about 40% of dreams, whereas aggressive interactions are somewhat more common, and occur in about 45% of dreams in a normative sample (Domhoff 1996). Strauch and Meier, however, point out that in their sample, neutral interactions were also common, and only about half of the social interactions in their sample could be classified as particularly friendly or aggressive. The third category of social interactions that has typically been quantified in dream reports is sexual interactions, but they occur at a very low frequency—in Strauch & Meier’s (1996) laboratory data, in less than 1% of REM dreams, and in the normative Hall and Van de Castle (Domhoff 1996) data, in 4% of women’s and in 12% of men’s dreams collected in a home setting.
In sum, the simulation of dream characters occurs very frequently, the characters are perceived and recognized by the Dream Self, and the Dream Self actively participates in communication, social interaction, and joint actions with the characters. The simulated characters are also for the most part realistic, stable, and represent a variety of different kinds of people. Their behaviours, however, may sometimes be unusual or inappropriate, and not exactly what we would have expected from their counterparts in real life. The tone of the interactions may be neutral, friendly, or aggressive.
When this evidence is taken together, we may conclude that dreaming simulates a rich, variable, realistic, and concrete, but somewhat unpredictable social reality, inhabited by a mixture of familiar, unfamiliar, and undefined people. Therefore, we have solid grounds to state that dreaming is, among other things, definitely a social simulation. If this is a universal and ubiquitous feature of dreaming, what kind of theory could explain it? Why does dreaming simulate social reality at all? It is by no means self-evident that this should be the case. Dreaming could as well be only a simulation of some basic features of the physical world: space, time, objects, events, and the perception of and bodily interaction with the physical world. Or it could be a simulation of thought processes, a thinking-through of our problems, or of our emotional states and concerns. Moreover, simulation of physical objects and their behaviour, or a replay of thinking and emotions, would probably be a simpler task for the brain than the simulation of a complex social world. Simulation of human bodies and faces and interactive behaviours such as conversations seems to require a lot of energy and computing power—these are very complex phenomena to simulate realistically. Thus, why does the sleeping brain simulate social situations in such an intense and invariant manner? Is there any convincing theoretical answer to be found to this question?