Dement & Kleitman (1957)

Sleep Study

What was the overall aim of Dement and Kleitman?

To investigate dreaming in an objective way by looking for relationships between eye movements in sleep and the dreamer's recall.

3 aims of this study?

1. Does dream recall differ between REM and nREM sleep?

2. Is there a correlation between subjective dream duration and the actual length of the REM period?

3. Are eye movement patterns related to dream content?

EEG

A machine that measures brain wave activity through electrodes placed on the scalp.

EOG

A machine that measures eye movement through electrodes placed around the eyes.

REM sleep

The sleep stage where we have vivid dreams. Our eyes move rapidly under our eyelids, but our bodies are paralyzed.

nREM sleep

The sleep stages (1-4) where our eyes are still. Deep, dreamless sleep occurs here.

Circadian Rhythm

A daily biological cycle that repeats about every 24 hours. The sleep/wake cycle is an example.

Ultradian Rhythm

A biological cycle that repeats more than once a day. The 90-minute sleep cycle (going through REM and nREM) is an example

Internal Validity

How sure a researcher is that only the variable they changed (IV) affected the outcome (DV), and nothing else.

Amplitude

The "height" or power of a wave on a graph (like an EEG readout).

Frequency

How often something happens in a fixed time. For example, the number of brain waves per second.

Biological Approach

he assumptions of the biological approach are that our emotions, behavior, and cognition:

1. Are controlled by biological systems and processes such as: brain function, genes, the nervous system, and hormones.

2. Can be investigated by manipulating and measuring biological responses such as: eye movements, brain activity, and pulse rate.

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How it connects:

The biological process focuses on explaining our emotions, behaviors, and cognition through things such as physiological processes and brain functioning. Dement & Kleitman's study investigated our brain functioning, specifically measuring our eye movements and brain activity through an EEG machine. This was done so that we could have an objective way to measure dream recall.

What were the procedures?

1. Ps went to the sleep lab at bedtime.
2. Electrodes for EEG (scalp) and EOG (around eyes) were attached.
3. Ps were woken by a doorbell during REM or nREM sleep.
4. They reported their dreams into a tape recorder

List 3 controls used in the study to improve validity.

1. Ps avoided caffeine/alcohol.
2. Standardized doorbell sound for waking.
3. Ps were not told which sleep stage they were.

Psychometrics?

Sleep lab - at University of Chicago

• EEG machine - to measure sleep objectively

• Electrodes – gathered at top of P’s head into a single cord

• Doorbell – used to wake up P’s

• Tape recorder – used to record P’s recollections of their dream content

Who were the participants (Ps) in the study?

9 adults

Gender of Participants (7/2)

-7 males

-2 females

-5 studied in detail

-4 used to confirm data over 1-2 nights

(Study 1: REM vs. nREM) What percentage of dreams were recalled from REM sleep vs. nREM sleep?

REM: 80% recall
nREM: 7% recall

Study #1 (REM vs. nREM): What was the Independent Variable (IV)?

Whether participants were woken from REM sleep or nREM sleep.

Study #1 (REM vs. nREM): What was the Dependent Variable (DV)?

Whether a dream was reported and, if so, the details of the dream.

(Study 1: REM vs. nREM) What was the main conclusion?

Dreaming is strongly associated with the biological state of REM sleep.

(Study 2: Dream Duration vs REM Duration) How accurate were Ps at estimating if they dreamed for 5 or 15 minutes?

5-min estimates: 88% accurate
15-min estimates: 78% accurate

Study #2 (Dream Duration): What was the Independent Variable (IV)?

Waking the participant after 5 minutes or after 15 minutes of REM sleep.

Study #2 (Dream Duration): What was the Dependent Variable (DV)?

The participant's choice of whether they had been dreaming for 5 or 15 minutes.

Study #2 (Dream Duration): What two variables were correlated?

The participant's time estimate (5 or 15 min) and the number of words in their dream narrative.

(Study 2: Dream Duration vs REM Duration) What was the main conclusion?

Dreams happen in “real time”

The events in your dream unfold in real time. A 10-minute dream actually takes about 10 minutes to happen.

(Study 3: Eye Movement Patterns) What did a dream with vertical eye movements involve?

Looking up and down (e.g., at climbers on a cliff).

Study #3 (Eye Movements): What was the Dependent Variable (DV)?

The participant's report of their dream content

Study #3 (Eye Movements): Could the researchers manipulate the IV?

No. They could not control the participants' natural eye-movement patterns; they could only observe and categorize them

(Study 3: Eye Movement Patterns) What did a dream with horizontal eye movements involve?

Watching movement side-to-side (e.g., people throwing tomatoes).

(Study 3: Eye Movement Patterns) What did participants report dreaming about when they had little or no eye movement?

They reported staring at a single object or watching something still in the distance (e.g., staring at a rock far away).

(Study 3: Eye Movement Patterns) What did participants report dreaming about when they had mixed eye movements?

They reported looking at people or objects that were close to them (e.g., watching people fight or talking to a group).

(Study 3: Eye Movement Patterns) What was the main conclusion?

Eye movements during sleep correspond to where the dreamer is "looking" in their dream.

What approach was this study?

They showed that a specific biological state (REM sleep) physically causes dreaming, linking a measurable bodily process to a psychological experience.

What research method ?

natural lab experiment

What research design was used ?

A repeated measures design (all participants experienced all conditions, e.g., being woken from REM and nREM sleep)

(G)eneralizability: What is the weakness?

Results may not apply to everyone.

-sample was too small (only 9 people, 5 studied in detail)

- lacked diversity (mostly men)

results may not apply to everyone.

(R)eliability: Why is it a strength?

• Highly standardized procedure.

• Controlled diet (no caffeine/alcohol).

• Same waking method (doorbell).

• Easy for other researchers to replicate.

(A)pplication: Why is it a strength?

• Foundation for modern sleep medicine.

• Used to diagnose sleep disorders (e.g., insomnia) in clinics.

• EEGs are used to monitor sleep patterns

(V)alidity: Internal Validity Why is it a strength?

• High level of control over variables.

• Researchers could be confident that REM sleep caused dreaming.

Validity- Why is it a weakness.

LOW ECOLOGICAL VALIDITY

-Artificial lab setting.

• Unnatural to sleep with electrodes on your head.

• Being woken up to report dreams is not a normal task.

(E)thics: Why is it a strength?

Confidentiality

• Only participants' initials were used (e.g., PM, KC).

• Protected their identities and private dream content.

(E)thics: Why is it a weakness?

Weakness: Protection from Harm.

• Sleep was disrupted many times.

• This likely caused fatigue and stress the next day.

NATURE vs. Nurture: Which does the study support?

Primarily supports Nature

Nature: Shows REM sleep and dreaming are universal biological processes.

NATURE

The content of dreams (e.g., cliffs, tomatoes) could be influenced by personal experience. The uncomfortable lab environment may have also affected sleep patterns.

What was the core scientific purpose of using different awakening patterns for participants like PM, KC, WD, DN, and IR?

To rule out expectation bias (the placebo effect) and prove that the link between vivid dreaming and REM sleep was a physiological reality, not a psychological artifact.

What was the specific role of participants PM and KC in the experiment?

They were woken randomly. This established the baseline, unbiased link between REM sleep and dream recall.

What was the key manipulation with participant WD and why was it critical?

He was woken randomly but was told he would only be woken from REM. His low dream recall on actual NREM wakes proved expectation wasn't enough; the physiology was key.

How did the protocol for DN (repeating pattern of 3 REM/3 NREM) strengthen the findings?

It tested if a predictable pattern could influence reports. The consistent results showed the effect was robust and not based on participant anticipation.

Sampling method

Oppurtunity sampling They used whoever volunteered and was available - no random selection from a big population. Just grabbed 9 adults (mostly males) who were nearby/willing to endure the inconvenience.

Research design

Repeated measures-same participants tested in REM vs nREm awakenings

Ethics

• Protection from Harm: Violation - Sleep deprivation from frequent awakenings affected next-day functioning

• Right to Withdraw: Not available - Participants slept overnight in lab with electrodes, hard to leave mid-session

• Informed Consent: Violation - Not told full study purpose (dream recall testing)

• Confidentiality: Followed - Used initials only

• Debriefing: Not available

• Deception: Violation - Woken "randomly" but actually targeted REM/nREM