Psychology (9990) | Dement and Kleitman (sleep and dreams)

Welcome to the Core Study Notes: Dement and Kleitman (1957)

Hi there! This chapter takes us into the fascinating world of sleep and dreams. As part of the Biological Approach, Dement and Kleitman's study is revolutionary because it showed us, for the first time, that we can study the biology of dreaming objectively—not just by relying on unreliable memories.

By linking physiological activity (eye movements) to psychological experience (dreaming), this study provides crucial evidence for how our brain activity (biology) influences our behavior and mental processes (psychology). Get ready to learn about the hidden life of your brain while you snooze!

1. The Biological Context: Sleep and Ultradian Rhythms

Assumptions of the Biological Approach

Remember, the Biological Approach explains behaviour using physical mechanisms.

• Brain Function: All thoughts, feelings, and behaviours are explained by the working of the brain and nervous system.
• Biological Factors: Behaviour is influenced by factors like hormones, genetics, and evolutionary adaptations.

Dement and Kleitman focus on a key biological concept: Ultradian Rhythms.

What are Ultradian Rhythms?

An ultradian rhythm is a biological cycle that occurs more than once every 24 hours.

• The sleep cycle, which repeats approximately every 90 minutes, is a perfect example.
• Within the sleep cycle, we move through different stages, including REM (Rapid Eye Movement) and NREM (Non-Rapid Eye Movement) sleep.

Quick Review: The core psychology investigated here is sleep, dreaming, and ultradian rhythms. These are all processes primarily controlled by the brain.

2. Dement and Kleitman (1957): The Relation of Eye Movements to Dream Activity

Background to the Study

Before this study, researchers had a big problem: how do you know if someone is dreaming? They had to wake participants up and ask them, which led to poor reliability.
In the 1950s, researchers discovered that periods of sleep involved bursts of rapid eye movements (REM). It was hypothesised that this stage might be related to dreaming, offering a new, objective way to study dreams.

Aim(s) of the Study

The study had three main aims, testing different aspects of the relationship between REM sleep and dreaming:

1. To test whether dreaming occurs primarily during REM sleep or NREM sleep (i.e., is REM linked to dreaming?).
2. To investigate if the length of the REM period correlates with the estimated length of the dream (i.e., do we dream in "real time"?).
3. To see if the pattern of eye movements (e.g., vertical, horizontal, little movement) corresponds to the content of the dream (i.e., are the eyes following the action in the dream?).

3. The Procedure: How They Studied Sleep in the Lab

(i) Participants and Setting

• Sample: Nine adult participants (seven male, two female). Five participants completed many nights, four completed only one or two nights to check consistency.
• Setting: This was a laboratory experiment conducted in a dedicated sleep lab. Participants had to sleep with electrodes attached to their faces and scalp.
• Sampling Technique: The sampling technique was likely an Opportunity Sample (volunteers from the surrounding area, though not explicitly stated).

(ii) Apparatus and Measurement (The Key Biological Tools)

The researchers used objective, physiological measures:

• EEG (Electroencephalograph): This machine measures brain wave activity (used to determine if the person was in REM or NREM sleep).
  Analogy: Think of the EEG like a seismograph for the brain; it records electrical activity beneath the scalp.
• EOG (Electrooculogram): Electrodes were placed near the eyes to measure eye movements.

(iii) Experimental Design and Controls

The study used a Repeated Measures Design (participants slept multiple nights) and incorporated aspects of a Correlational Study (looking for relationships between REM duration and dream recall).

Key Controls:

• Participants avoided alcohol and caffeine (stimulants that affect sleep) prior to the study.
• They were woken by a door knock and immediately told to recall their dream into a recorder.
• The EEG was used to confirm they were in the correct stage of sleep before waking them up.

(iv) The Three Experiments (Connecting aims to procedures)

Experiment 1 (REM vs. NREM):

The researchers woke participants during both REM and NREM sleep, asking them: "Did you dream?" and "What was the content?"
The Independent Variable (IV) was the stage of sleep they were woken up in (REM or NREM).
The Dependent Variable (DV) was the recall of the dream.

Experiment 2 (REM Duration and Dream Length):

Participants were woken either 5 minutes into a REM period or 15 minutes into a REM period.
The IV was the length of the REM period (5 minutes or 15 minutes).
The DV was the participant's estimate of the dream length.

Experiment 3 (Eye Movements and Dream Content):

Participants were woken up after specific patterns of eye movement were observed (e.g., vertical, horizontal, or none). The contents of their reported dreams (Qualitative Data) were compared to the pattern recorded on the EOG.

4. Results and Conclusions

(i) Experiment 1: REM vs. NREM Dreaming (Quantitative Data)

• Dream recall was much higher when participants were woken during REM sleep (around 80%) compared to NREM sleep (around 9%).
• Dreams reported during NREM tended to be less visual and more related to general feelings, rather than detailed narratives.
• Key Quantitative Finding: The likelihood of recalling a dream is biologically tied to the REM stage.

(ii) Experiment 2: Duration of REM and Dream Length (Correlational Data)

• Participants were highly accurate when asked to estimate if they had been dreaming for 5 minutes or 15 minutes.
• The number of words in the dream narratives also showed a positive correlation with the length of the REM period before waking.
• Conclusion: Dreaming is experienced in real time. A 15-minute dream takes about 15 minutes of REM sleep.

Did you know? This finding was groundbreaking! Before D&K, some theories suggested that the entire dream was only formed in the brief moment of waking, like a quick memory flash. This study proved that dreams are an active, real-time process.

(iii) Experiment 3: Eye Movements and Dream Content (Qualitative Data)

The qualitative reports suggested a link between the direction of eye movements and the dream’s content:

• Vertical movements: Reported dreams involved vertical action, like climbing a ladder or looking up and down a cliff.
• Horizontal movements: Reported dreams involved looking side-to-side, such as watching two people throw tomatoes at each other.
• Little or no movement: Dreams often involved looking at distant, stationary objects, like driving a car for a long period.

Overall Conclusion:

Dreams are a biological phenomenon that primarily occurs during REM sleep and unfolds in real-time. The eyes moving during REM are not random, but reflect the activity or visual experience of the dream world.

Key Takeaway: Dement and Kleitman successfully provided an objective method (using the EEG/EOG) to study the subjective experience of dreaming.

5. Evaluating Dement and Kleitman's Methodology

Strengths (Why the Study is Good)

• Objective Measurement (Scientific): The use of the EEG and EOG provides physiological, objective data, which is highly scientific. This avoids the problems of relying purely on subjective, unreliable self-report.
• High Control (Reliability): The study was conducted in a controlled lab setting. Variables such as avoiding caffeine/alcohol, the use of a doorbell to wake participants, and strict monitoring of brain waves make the procedure highly reliable. Other researchers could easily replicate this study.
• Mixed Data: The study gathered both quantitative data (e.g., percentages of dream recall, minutes of REM) and qualitative data (the content of the dreams). This provides a rich and detailed understanding of the results.

Weaknesses (Why the Study is Limited)

• Low Ecological Validity: Sleeping in a lab with electrodes stuck to your head and face is not a natural environment. This artificial setting (and the knowledge that they would be woken up) may have affected participants' sleep patterns, making the results less generalisable to everyday sleep.
• Small Sample Size: Using only nine participants (and only five extensively) makes it difficult to draw definitive conclusions about the dreaming behaviour of the entire population. The results might be specific only to those nine individuals.
• Ethical Issues (Privacy/Withdrawal): Participants were constantly monitored, reducing their privacy. Although they could withdraw, being woken repeatedly may have caused temporary harm or discomfort.

6. Issues and Debates in Dement and Kleitman

Nature versus Nurture

This study strongly supports the Nature side of the debate.

• Nature Evidence: Dreaming is inherently biological. The fact that the REM stage (a physical, biological state) is consistently linked to dreaming suggests that dreaming is an innate, universal human function, genetically programmed into our biological sleep cycle.
• However, the *content* of dreams (Qualitative Data) is likely influenced by external experiences and learning (Nurture), suggesting an interaction between the two.

Application to Everyday Life

The findings have significant real-world applications:

• Sleep Disorders: By accurately mapping the stages of sleep using the EEG/EOG, doctors can now diagnose and understand sleep disorders (like insomnia or narcolepsy) more accurately based on biological irregularities in their REM/NREM cycles.
• Dream Research: The objective measurement technique laid the foundation for decades of further research into brain activity during various sleep stages.

Individual and Situational Explanations

The study leans towards a Situational (biological context) explanation.

• Situational (Biological) Factors: The stage of sleep (the situation the brain is in, i.e., REM vs NREM) dictates whether dreaming occurs and how vivid it is. This suggests the biological situation is key.
• Individual Differences: Despite the strong trends, there were still individual differences in dream recall and eye-movement patterns, showing that individual biology slightly varies.