The Function of Dreams and Dreaming
Moving towards an integrated understanding
Lena Sayed
A thesis for the Professional Programme,
The Department of Psychology
UNIVERSITY OF OSLO
April, 2011
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Understanding Dream Research: A Look into Theories, Definitions, and Functions, Thesis of Psychology
The complex field of dream research, discussing the lack of consensus in theories, definitions of dreams, and their potential functions. It covers topics such as dream phenomenology, problem-solving, and dreaming as a simulation of threatening events. The document also evaluates major dream theories and their implications.
What you will learn
- What are the implications of dream research for psychology and cognitive science?
- How does dream research define dreams and dreaming?
- What are the major theories in dream research?
- How can dream research be integrated to better understand neurophysiology?
- What are the functions of dreams according to various theories?
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The Function of Dreams and Dreaming
Moving towards an integrated understanding
Lena Sayed
A thesis for the Professional Programme,
The Department of Psychology
UNIVERSITY OF OSLO
April, 2011
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Abstract
Author: Lena Sayed Title: The Function of Dreams and Dreaming: Moving towards an integrated understanding. Supervisor: Professor Bruno Laeng This theoretical essay investigates theories concerning the function of dreams and dreaming starting with the contributions made by Freud (1900) to the present day. Several theories within psychodynamic, evolutionary and neurocognitive perspectives are presented and discussed in light of relevant empirical research. These include theories which postulate that the function of dreaming is to guard sleep (Freud, 1900) and theories which propose that dreaming poses an adaptive advantage either by allowing for the simulation and rehearsal of threat avoidance behaviours (Revonsuo, 2000), practicing social skills (Franklyn & Zephyr, 2005), solving emotional or intellectual problems (e.g. Barrett, 2007; Hartmann, 1996) or aids us in the consolidation of memories (Paller & Voss, 2004). Theories that view dreaming as being functionally epiphenomenal are also discussed, such as proposals that dreaming is a by- product of the development of specific cognitive abilities (Domhoff, 2010) or merely a reflection of sleep-related changes which occur in the brain (Hobson, Pace-Schott & Stickgold, 2000). It appears that the theories presented in this essay are limited in accounting for much of the empirical evidence derived from the content analysis of dreams and the study of related neural correlates, and few attempts have been made at integrating some of the perspectives to provide a more comprehensive understanding of the nature and function of dreams and dreaming. Possible reasons for this are discussed, as well as proposals for how several theories may be integrated, followed by suggested avenues for future research and concluding remarks.
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Foreword
Last summer I was struggling with my initial research project when the last participant dropped out of my study. After almost a year of work I realised that I had no choice but to start again with another thesis topic. I considered several fields of study to centre a theoretical essay around but none seemed to re-spark my enthusiasm, when one morning I awoke from a dream that I wrote my thesis on the function of dreaming. Dreaming has fascinated me since I was young and I was surprised after studying psychology for several years that the topic had hardly been broached. After completing this thesis I realise that there is probably little focus on this area of study due to the lack of a comprehensive understanding of why we dream. It has been a pleasure spending the last semester of my studies immersing myself in theories of dreaming and contributing with my own suggestions as to how an integrated understanding of the function of dreams may be developed. I would like to thank my supervisor, Professor Bruno Laeng, for invaluable help and feedback, and my friends and family for providing encouragement and support. Finally I would like to express gratitude to my lovely man for providing comfort and patience throughout the process.
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3.2.3! Dreaming as problem-solving .............................................................................. 30! 3.3! Neurocognitive theories............................................................................................... 34! 3.3.1! A new cognitive approach to dreaming................................................................ 34! 3.3.2! Activation-Synthesis hypothesis and the AIM model .......................................... 37! 3.3.3! Dreaming as memory consolidation..................................................................... 41! 3.4! General Discussion...................................................................................................... 45! 3.4.1! A proposed framework for integrating dream function........................................ 46! 3.4.2! Avenues of future research................................................................................... 51! 4! Conclusion.......................................................................................................................... 54! References ................................................................................................................................ 55!
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1 Introduction
1.1 Objectives
Dreams and the process of dreaming have fascinated mankind since ancient civilizations to modern times, although its systematic and scientific study is only a recent development (Hobson, 2009). As early as in 350 B.C. Aristotle stated that “We must inquire what the dream is, and from what cause sleepers sometimes to dream, and sometimes do not; or whether the truth is that sleepers always dream but do not remember, and if this occurs what is its explanation” (para. 2). Since then 23 centuries have passed and a plethora of theories have been proposed as to the nature of dreaming. Within the realm of psychology and psychiatry, interest in the topic was first sparked by Sigmund Freud (1900), who proposed that dreams act as ‘the guardians of sleep’ by providing a protective role which allows the expression of repressed unconscious wishes without disturbing sleep itself. Consequent theories pertaining to the function of dreaming reflect a wide range of diverging perspectives including psychodynamic theories (e.g. Solms, 1997) evolutionary models (e.g. Revonsuo, 2000 ) and neurocognitive models (e.g. Hobson, Pace-Schott and Stickgold, 2000) The lack of consensus between theories in the field of dream research may be partly attributed to dreams being innately difficult to study due to their subjective nature. As of yet, dream content cannot be directly observed and it is difficult to manipulate dreams experimentally making it nearly impossible to predict the contents of specific dreams (Arkin & Antrobus, 1991). As a result contemporary dream research has made a shift from investigating dream content of specific dreams to investigating neural activity of the collective properties of all dreams, thus moving from content to form (Nir & Tononi, 2009). Despite this shift, promising work has been done attempting to link dream phenomenology to neurophysiology although there is still little consensus between dream researchers and few attempts have been made to integrate diverging perspectives (Barrett, 2007). The aim of this theoretical essay is to examine the major psychological theories related to dream research in an attempt to provide an integrated framework under which the function of dreams and dreaming can be understood. Firstly, a definition of dreams, dreaming and function will be presented along with a brief explanation of the physiology of sleep and dreaming. This will be followed by the theoretical background, which provides an outline of major theories concerning dream function, ranging from the psychodynamic to the
neurocognitive. These theories will consequently be discussed in light of relevant empirical research, followed by a suggested framework under which several of these theories can be integrated. Finally possible avenues of future research will be discussed along with concluding remarks.
1.2 Definitions
1.2.1 Dreams and dreaming
The lack of consensus in the field of dream research is also reflected in the lack of a widely accepted definition of dreams and dreaming. According to the American Heritage Dictionary of the English Language (2000) dreams are “a succession of images, ideas, emotions and sensations occurring involuntarily in the mind during certain stages of sleep”. In psychology and neuroscience Hobson (2002) offers a simpler definition of dreams and dreaming as “mental activity occurring during sleep” (p. 7). Some definitions of dreaming also include a component relating to consciousness. For example Revonsuo and Tarkko (2002) define dreaming as “a subjective phenomenon of consciousness produced by the brain with absent or only minimal contributions from external sensory stimulation” (p. 4). Other definitions within research on dreaming often focus on the proposed function of dreams and thus vary in accordance with what perspective is emphasized. For example, Hobson (2002) provides a definition of dreams and dreaming based on their proposed biological substrates: “The experience during sleep caused by selective activation of brain circuits underlying emotion and selective inactivation of brain circuits and chemicals underlying memory, directed self- reflective awareness and logical reasoning” (p. 6). However, researchers who attribute dream experiences to other processes or neural networks would most likely not accept this definition (e.g. Solms, 2002). For the purpose of this essay the definition of dreams and dreaming as “mental activity occurring during sleep” (Hobson, 2002, p.7) will be employed due to its simplicity.
1.2.2 Function
According to Tooby and Cosmides (1995) the only relevant standard of functionality when attempting to determine why brain and cognition are organised in a certain way is the
4 sleep has a higher proportion of such waves (more than 50 %) than stage 3 sleep (20-50%). In 2007, these stages were combined by the American Academy of Sleep Medicine to form a single stage due to their lack of distinction (cited in Schulz, 2008). Following 90 minutes of sleep onset a sudden change occurs where the eyelids start to dart back and forth between the closed eyelids, the EEG becomes mostly desynchronized and the EMG indicates a profound loss of muscle tonus. This is referred to as rapid eye-movement (REM) sleep and includes a small amount of theta waves along with beta activity, which is usually seen during wakefulness or stage 1 sleep. REM-sleep lasts for 20 – 30 minutes whereby the sleep cycle starts again alternating between REM and NREM-sleep. Each cycle lasts for approximately 90 minutes, thus an 8-hour long sleep will contain four or five periods of REM-sleep, which become more prolonged for each cycle. Most of the slow wave sleep occurs in the first half of the night and subsequent bouts of NREM-sleep consist increasingly of stage 2 sleep (Carlson, 2004).
1.3.2 The discovery of REM-sleep
In the early 1950s Aserinsky and Kleitman attempted to systematically investigate the possibility that REM-sleep was somehow associated with dreaming. In their observations of sleeping infants, and later adults, they hypothesised that the physiological changes which occur when entering REM-sleep suggest an emotional ‘disturbance’ which may indicate dreaming. Aserinsky and Kleitman (1953) and later Dement and Kleitman (1957) awakened subjects from the midst of their REM-sleep and discovered that on average 70% of these awakenings yielded dream reports. This discovery linking the phenomenon of dreaming with the physiological occurrence of REM-sleep has now been confirmed in numerous studies and marks one of the first and most groundbreaking findings in dream research (Franklin & Zyphur, 2005). Although subsequent studies have demonstrated that dreaming may also occur in NREM-sleep (e.g. Foulkes, 1962), the theories that form the basis of this theoretical essay invariable differ as to the importance they give dreaming in NREM. Some dream researchers such as Solms (2000), actually use the lack of focus on dreaming in NREM as the basis for their critique of competing theories. The occurrence of dreams in NREM-sleep and its implications for theories of dream function will be further elaborated in the following section, as well as in the Discussion.
2 Theoretical background
There is a wide spectrum of theories pertaining to the function of dreams and dreaming (Dallett, 1973) and for the purpose of this essay is it not possible to review them all. However, there is a great deal of overlap among the various theories and it is possible to provide an outline of some of the most representative perspectives on dream function in the psychology literature. In the current essay, these have been divided into three main subsections: Psychodynamic, Evolutionary and Neurocognitive theories. Although some specific accounts may intersect into more than one category they have been placed in the subsection considered to most accurately reflect their central tenets. Each perspective to be outlined here will be expanded upon and evaluated in the Discussion in light of relevant empirical research. Some theories which have previously garnered much attention and stimulated the debate on dream function (e.g. Crick & Mitchison’s, 1983, “reverse learning” hypothesis) will not be included in this theoretical essay if they have subsequently been rejected by the majority of current dream researchers due to a lack of empirical support.
2.1 Psychodynamic theories
2.1.1 Freud
We begin in chronological order, with theories that emerged from the psycho-analytic movement. At the end of the 19th^ century it was generally thought that dreams are reactions to external or internal stimuli that they most often occurred during the process of waking and were brief in duration (Domhoff, 2002). Some writers, such as Alfred Maury (1853), emphasized the role played by waking experiences and insufficiently-inhibited emotions in the process of instigating dreams. Sigmund Freud (1900) tried to bring some of these perspectives together in his influential book “The Interpretation of Dreams”, combining them with his ideas about the role of the unconscious and his novel theories of neurosis. This was the first attempt in the field of psychology and psychiatry at providing a systematic theory pertaining to the function and processes involved in dreams and dreaming (Fisher & Greenberg, 1996). Freud (1900) viewed a neurotic symptom as a product of trying to satisfy both a conscious wish and a conflicting, unconscious, repressed wish. He posited that, during
A further elaboration on the aspects and processes Freud proposed to be involved in dreaming will be provided in the discussion when presenting relevant empirical research.
2.1.2 Jung
The Swiss psychiatrist Carl G. Jung was considered one of Freud’s closest friends and most promising students until they had a falling out in 1914, partly as a result of their differing views as to the nature and function of dreaming (Homans, 1979). Jung opposed Freud’s theory that dreams intentionally disguise their meanings, arguing instead that dreams are a natural and direct expression of the dreamer’s current concerns (Jung, 1967). Jung claimed the nature of dreams is to present “a spontaneous self-portrayal, in symbolic form, of the actual situation in the unconscious” (Jung, 1967, Vol. 8, para. 505). He believed we have difficulties understanding dreams when conscious because they adhere to the language of our unconscious. This language involves the use of images, metaphors, and symbols (Jung, 1967). Jung (1967) distinguished between objective and subjective levels of a dream’s meaning. The objective level of a dream’s meaning is related to activities of the dreamer’s daily life in the external world such as people, events and activities. The subjective level of a dream’s meaning relates to the inner world of the dreamer such as thoughts and feelings, where characters in dreams may be personifications of these. Jung (1967) criticized Freud for only focusing on the objective level of a dream’s meaning, neglecting the subjective level. Jung believed that the true nature of dreams is to portray both these levels of the dreamer’s life. Jung (1967) believed that in addition to expressing personal content, dreams might also reflect collective or universal content in the form of archetypes. Archetypes, according to Jung, refer to primitive mental images which are inherited from the earliest human ancestors and present in the collective unconscious (Fordham, 1966). Jung claimed that archetypes reflect a natural wisdom buried deep in the unconscious which can serve to guide the dreamer towards achieving wholeness by providing insights. According to Jung (1967) dreams serve two functions. The first is to compensate for imbalances in the dreamer’s psyche by expressing content from the unconscious that the dreamer has actively repressed, ignored or depreciated. For example a person who is overly intellectual may have dreams which express the psyche’s emotion-oriented content in an effort to achieve greater psychological balance. For this to occur it is important that the
dreamer accepts and recognizes the unconscious content. Jung (1967) believed that the second function of dreams is to provide prospective images of the future. This does not imply that dreams predict the future but rather generate possibilities and anticipations of what the future might hold for the dreamer. Ultimately, Jung believed the true function of dreams is to unite the conscious and unconscious in a healthy and harmonious state of wholeness. Jung (1967) termed this process ‘individuation’ and regarded it as the most important developmental process in human life.
2.1.3 Solms
The psychoanalyst Mark Solms (1997) based most of his theory of dreaming on clinico- anatomical studies of patients suffering from a wide variety of brain injuries. Solms (2000) developed several hypotheses concerning which anatomical areas of the brain are necessary for dreaming, in an attempt to integrate findings from neuropsychology and psychoanalytic theory to create a new field called neuropsychoanalysis (Solms & Turnbull, 2002). In his research, Solms (1997) compared brain scans and psychological tests with changes in dreaming reported by patients following their brain injuries. Solms’ (1997) findings that dreaming is closer associated with neural networks in the forebrain rather than previous claims that dreaming is associated with neural networks in the brain stem (Hobson & McCarley, 1977) led him to a series of conclusions. Firstly, he suggested that the notion of dreaming as merely “an epiphenomenon of REM-sleep” (Hobson, Stickgold & Pace – Schott, 1998, p.12) was flawed, as dreaming was also found to occur during NREM-sleep and activity in the brain stem observed during REM-sleep (assumed to result in dreaming) was not present when dreaming in NREM-sleep (Solms, 2000). Secondly, the Freudian theory had wrongly been rejected on the basis of these previous, faulty, claims that REM-sleep and thus dreaming was a ‘mindless’ activity, due to their presumed connection with random signals arising from the tegmental region of the pons (this claim will be further elaborated on in the section concerning Hobson and McCarley’s, 1977 , activation synthesis hypothesis). According to Solms and Turnbull (2002) the functions Freud attributed to the ‘libidinal drive’ (the primary instigator of dreams) equates to the main function of the forebrain; that is “to motivate a subject to seek out and engage with external objects which can satisfy its inner biological needs” (Solms, 1999, p.5). Thus, he argues that the findings that dreaming is associated with neural dopaminergic networks in the forebrain can be taken as evidence for the Freudian theory of dreams. Solms (1999) summarises this as follows: