Sleep and Dreaming - Lecture 14: Theories of Dreaming

Theories of Dreaming

Functional Theories of Dreaming

• Several theories propose that dreaming serves a specific function.

Hartmann's Making Connections in a Safe Place Theory

• Hartmann E (1995). Making Connections in a Safe Place: Is Dreaming Psychotherapy? Dreaming, 5: 213-228.
• Dreaming and psychotherapy both involve freeing associations without acting them out, providing a safe environment facilitated by muscular paralysis.
• Associative Function After Trauma:
  • Hartmann suggests that the associative function of dreams is most evident following trauma.
  • Dreaming and psychotherapy facilitate connections between trauma and related memories.
  • Dreams initially replay the trauma and then evolve to incorporate related material through metaphor.
  • The dominant emotion remains consistent throughout this transformation.
  • In both dreaming and psychotherapy, the trauma and associated disturbing affect are eventually integrated into the individual's life.
• Broad and Peripheral Connections:
  • Hartmann posits that dreaming establishes broader and more peripheral connections compared to waking thought.
  • Dreaming is hyperconnective, characterized by a wider spread of excitations than the more focused thought processes of waking life (Hartmann, E. (1996). Outline for a theory on the nature and functions of dreaming. Dreaming, 6, 147-170).
• Contextualizing Emotion:
  • Dreaming contextualizes emotion, metaphorically explaining the dreamer's emotional state, a process considered functional.
  • Example: A new mother concerned about her children might dream of them being lost in a storm, reflecting her emotional state.
• Thin-Boundary State:
  • Dreaming is considered a thin-boundary state, varying within individuals between sleep and wake.
• Forgotten Dreams:
  • Although most dreams are forgotten, cross-connections can still occur without conscious recollection of the connection made during sleep.
  • This aligns with memory enhancement views of sleep, particularly REM sleep.

Revonsuo's Threat Simulation Theory & Social Simulation Theory

• Revonsuo's (2000) Threat Simulation Theory is presented as a virtual reality theory, contrasting with mnemonic or emotional processing theories.
• Core Concept: Dreaming is a selective simulation of the waking world and its threats, allowing individuals to practice overcoming these threats.
• Evolutionary Basis: The theory suggests that dreaming evolved as a biological defense mechanism, rehearsing threat perception and avoidance to increase reproductive success.
• Empirical Evidence: Studies on traumatized children support the theory, showing that those in threatening environments have more frequent and severe threatening events in their dreams (Valli et al., 2005).
• Social Simulation Theory (SST): Revonsuo et al. (2015) expanded the theory to include the simulation of social reality, not just physical threats.
  • SST posits that dreams simulate social skills, bonds, interactions, and networks engaged in during waking life.
  • Tuominen et al. (2019) tested the Sociality Bias and Strengthening hypotheses of SST, finding that dreams overrepresented social events compared to waking reports, supporting the Sociality Bias hypothesis.

General Considerations for Functional Theories

• What Defines a Function:
  • Dreaming having a function implies that humans evolved to have specific types of dreams that provide a reproductive advantage.
  • Even dreams not remembered upon waking or occurring during sleep are considered beneficial.
• Memory Consolidation:
  • Dreaming has also been linked to memory consolidation by Wamsley and Stickgold.
  • During sleep, the brain processes new memories, consolidates them into long-term storage, and integrates new information with past experiences.
  • Dreaming is viewed as reflecting functional neural processes during sleep.
  • Quote: “Dreaming is the poor man’s fMRI!” - Bob Stickgold, 2012

Arguments Against Dream Function

• Specificity of Content: Dream content is often abstract and not directly related to what is being learned.
• Sleep Stages: Declarative memory processing occurs mainly in Slow-Wave Sleep (SWS), where dreaming is less frequent, while skill learning happens in REM sleep, but dreams rarely involve skill learning.

Competing Perspectives

• Nielsen & Levin: Dreams extinguish fear memories by simulating waking life.
• Revonsuo: Dreams allow us to practice overcoming threats.
• Hartmann: Dreams facilitate connecting memories by processing emotional events from waking life.
• Wamsley & Stickgold: Dreams reflect the processing of recently acquired memories.

The Null Hypothesis

• The null hypothesis suggests that we simply dream of waking life without any specific functional purpose.
• Versions of the Null Hypothesis:
  • Continuity Theory (Domhoff & Schredl): Dreams mirror waking life and reflect our waking thoughts.
  • Activation-Synthesis Theory (Hobson): Dreams are a scrambled version of waking life memories.
• Flanagan's (1999) book, Dreaming Souls, supports the null hypothesis.
• Spandrels: Dreams are considered decorative 'spandrels,' non-functional by-products of evolution that are not harmful and thus not selected out.

Challenges to the Functional View

• Wamsley et al. (2010) Study:
  • Dreaming of a learning task was associated with enhanced sleep-dependent memory consolidation.
  • However, it was also linked to poor baseline scores, suggesting those worried about their performance were more likely to dream about the task.
  • This raises the question of whether dreaming is causal in improving performance or merely a result of the previous day's experience.
• Wamsley & Stickgold (2019) Replication:
  • Found that pre-sleep training on a virtual maze navigation task was reflected in dreams and associated with improved next-morning performance.
  • However, dreaming of the task was again associated with poor initial learning performance before sleep, confounding the results.
• Language Learning: Learning French is related to language learning mistakes in dreams, which is unlikely to be cognitively helpful (De Koninck et al., 2012).
• Inverted Vision: Vertical inversion of the visual field and REM sleep mentation. Mistakes in dreams was associated with poor learning of the inverted vision. (De Koninck et al., 1996).
• Epiphenomenon: Dreaming may be an epiphenomenon, a non-functional by-product of neural processes, like noise from a factory.

Potential for Dream Function

• Dreaming may reflect higher-level learning, restructuring, or interpersonal emotional/social learning in REM sleep.
• Dreams could be related to social learning, such as reflecting on how one was treated or felt during the day.
• Dreams are often very social, involving many characters.

Key Questions

• Do dreams index (reflect or indicate) functional brain processes during sleep, such as those in the Default Network?
• Or are they the result of non-functional brain processes?
• If the latter, non-remembered dreams have no lasting effect on cognition.

Dream-Lag Effect

• The dream-lag, the delayed incorporation of waking life experiences into dreams, might suggest a function of dreaming, as it's hard to explain if dreams are just a residue of recent emotional life.

Uncertainty About Dream Function

• It is currently unknown whether dreaming has a function.
• There is also uncertainty about whether waking consciousness itself has a function.

Ros Cartwright's Research

• Cartwright (1991): Studied dreams of people undergoing divorce, finding that incorporation of the spouse in dreams was associated with less depression later on.
• However, this is a correlational study, making it difficult to establish causation.
• It's plausible that those better able to recover from the divorce were also more able to dream of the spouse during the divorce.

Methodological Challenges

• All studies relating dream content to waking life changes are correlational, making it impossible to demonstrate causation.
• Researchers cannot randomly assign participants to dream content conditions to observe the effects.

Siclari et al. (2017) Paper

• This paper may provide clues about whether dreaming has a function.
• Key Finding: Dreaming occurs in both NREM and REM sleep when the posterior hot zone is activated.
• The activation of the posterior hot zone is a pure measure of consciousness.
• Future research aims to determine why this zone is activated and whether virtual simulation is necessary for memory processing.
• The neural correlates of dreaming F Siclari et al,

Conclusion on Dream Function

• It remains unknown whether dreaming has a function.
• A potential function could be increasing self-awareness.

Dream Content, Creativity, and Insight

• This is distinct from the question of whether dreaming has cognitive, memory, emotional, or virtual reality functions.
• Distinguishing continuity/discontinuity, function, and insight when investigating dream content Commentary on "The continuity and discontinuity between waking and dreaming: A Dialogue between Michael Schredl and Allan Hobson concerning the adequacy and completeness of these notions" Mark Blagrove Int J of Dream Res, 2011, 4, 45-47
• It may be that all current data on the causes of dream content allow for the null hypothesis of dream function, that is, dreams do not have a function and dreaming has not been selected for during evolution.
• the experimental designs currently used are of necessity correlational rather than a random assignment to dream content conditions.

Evolutionary Function and Insight

• Flanagan and Domhoff suggest dreaming is an epiphenomenon, like factory noise, or a by-product of waking life imagination, though a complicated one.
• Domhoff (2011). Dreams are embodied simulations that dramatize conceptions and concerns.

Claims of Dreams and Insight

• Kekulé's Benzene Ring: The claimed insight of Kekulé about the circular shape of the benzene ring after dreaming of snakes eating their own tails.

Measuring Insight and Creativity

• Assessing insight and creativity is challenging due to difficulties in evaluating novelty and validity.

Karlheinz Stockhausen's Helicopter Quartet

• In 1991, Stockhausen was commissioned to compose a string quartet.
• He had a dream where he saw four string players in four helicopters, with the sound of the blades mixed with the strings.
• This led to his Helicopter Quartet, a unique musical piece.

Summary of Dreams and Insight

• Testing the hypothesis that dreams are a source of insight is difficult.
• Whether dreams can be a source of insight needs to be tested experimentally, similar to the Ullman dream group studies.