Dement and Kleitman

#rem by ariana grande

Psychology being investigated:

* Sleep is an altered state of consciousness
* Dreams are vivid sequences of imagery that occur during sleep
* EEGs measure brain wave activity - they measure the amplitude and frequency of brain waves
* REM: a phase of sleep where someone is paralysed
* There are 4 stages of sleep (1 is the lightest, 4 is the deepest)

Background:

Aserinsky and Kleitman:

* Using an EEG to explore the relationship between sleep and dreaming
* Ppts woken from REM were more likely to report a vivid, visual dream
* REM sleep changes brain waves, reduces body muscle activity, increases breathing and heart rates

Aims

To investigate the relationship between eye movements and dreaming:


1. Does dream recall different between REM and nREM stages of sleep?
2. Is there a positive correlation b/t subjective estimates of dream duration and the length of the REM period before waking?
3. Are eye movement patterns related to dream content?

Hypotheses:

1. There will be a significant association between REM sleep and dreaming.
2. There will be a positive correlation between estimated dream duration and REM period length.
3. There will be a significant association between eye movement patterns and dream content.

Research method:

Lab experiment

* Self-reports (for Q3)

Research design for Q1

Repeated measures design

IV: whether the ppt was woken from REM or nREM

DV: whether they recalled a dream or not

Research design for Q2:

A correlational study

IV: waking ppts after 5 or 15 mins

DV: ppts guess on dream duration

Research design for Q3:

Repeated measure design

IV: eye movement patterns

DV: dream content

Sample

7M and 2F - opportunity sampling

* 5 studied in detail and 4 used to confirm these results
* 5 main ppts spent b/t 6-17 nights in lab (approx. 50-77 awakenings)
* 4 spent only 1-2 nights (10 awakenings)
* Ppts identified by initials

What were ppts not allowed to consume?

Caffeine-containing drinks and alcohol

The ppt arrived at the lab just before..

their normal bedtime

All ppts slept in a:

dark, quiet room

Where were electrodes attached to ppts?

Beside the eyes and only the scalp, which fed into the experimenter’s room

* The wires were gathered together into a single cord - like a ponytail, which allowed them to move easily

Ppts were woken by a…

doorbell at various time during the night when an eye movement pattern lasted for a least a minute, then they returned back to sleep within 5 minutes

For Aim 1, how was waking ppts from nREM or REM decided?

1. Random # table (PM and KC)
2. In groups of 3 REM, then 3 nREM (DN)
3. Telling the ppt they’d only be woken in REM, but waking them randomly in nREM or REM (WD)
4. No specific order, experimenter chose (IR)

After being woken, the ppt stated…

whether or not they were having a dream and described its content into a recorder

* When the ppt had finished, the experimenter sometimes entered the room to ask further questions about the dream (only communication b/t experimenter and ppt)

Dreams were only counted…

if the ppt had clear recall of the dream

How was ppts’ estimations of sleep duration first attempted to be measured?

Ppts were told to estimate the time they’d been dreaming to the nearest minute, and weren’t given a fixed choice

What happened when testing Aim 2?

The ppt was woken after either 5 or 15 minutes into REM sleep

* They then guessed this duration of REM
* The # of words in dream narrative after each duration was counted

What happened when testing Aim 3?

The direction of eye movements was detected using EEG electrodes around the eyes

* Ppts woken after a single eye-movement pattern had lasted for over 1 minute + asked to report dream

What were the eye-movement patterns?

1. mainly vertical
2. mainly horizontal
3. both vertical and horizontal
4. very little/no movement

General findings:

All ppts dreamed every night

Dream stages last 3-50 minutes (mean of 20 mins)

* They were typically longer later in the night
* Showed intermittent bursts around 2-100 REMs

How long was the cycle length b/t dream stages?

92 minutes was the average time gap; the range was 70 - 104 minutes.

When ppts were woken from nREM they returned to…

nREM

When ppts were woken from REM…

they typically went back into nREM, except during the final REM phase of the night

Results for Aim 1:

* Ppts were able to recall a dream in 152/191 awakenings from REM (79.6%)
* But, for 93.1% of nREM awakenings they did NOT recall a dream
* In 5/17 nREM awakenings within 8 minutes after the end of a REM stage, dream were recalled
* During awakenings in periods longer than 8 minutes after a REM stage, only 6/132 dreams were recalled
* nREM awakening = feelings not specific dream content
* Ppts least likely to remember a dream if they were woken at the stage of sleep where the EEG has ‘spindles’

For Aim 1, DN was…

no more or less likely to report/not report dream in REM or nREM than other ppts

* He often underestimated how long he was dreaming for

Absence of dreaming in REM was more common…

early in the night for the entire sample:

* 19/39 REM awakenings w/o dreams were within the first 2 hours of sleep

Results for Aim 2:

The estimation of REM duration was accurate:

* 5 mins (88%)
* 15 mins (78%)

The correlation of duration of REM period and # of words in the dream were all…

significantly positive correlations

* Ranged from r = .4 to .71

Narratives from dreams recalled after 30-50 mins of REM were…

not much longer than those after 15 mins of REM

Results of Aim 3:

Eye-movement patterns are related to dream content:

* Based on 35 awakenings:
* Mainly vertical (3 dreams):
* Standing at the bottom of a tall cliff and operating a hoist, while watching climbers on the cliff
* Mainly horizontal:
* Watching 2 ppl throwing tomatoes at each other
* Little/no movement (10 dreams):
* Watching something in the distance/staring at something
* Driving a car and staring ahead but he was startled by a speeding car to his left
* Mixed movements (21 dreams):
* Talking to a group of people or looking for something

There were more dreams recalled in the..

second half of the night compared to the first half for the entire sample.

Conclusions:

* Dreams occur during REM sleep only. Dreams reported from NREM sleep are from previous REM episodes.
* Estimated dream duration and REM period lengths are very similar, thus it shows that dreams are not instantaneous events but rather experienced in real-time.
* Eye movements correspond to where, and what the dreamer is looking at in the dream, hence, it explains that they are not random events.

Why was using a lab experiment a strength?

Possible to limit the effect of uncontrolled variables:

* If some ppts had woken more slowly they may have forgotten more of their dream - the loud doorbell woke ppts instantly
* Ppts weren’t told about their EEG pattern or whether their eyes were moving, eliminate potential demand characteristics

How was validity raised in the experiment?

* The definition of a 'dream' had been operationalised as a recollection that included content
* Asking participants to choose between 5 or 15 mins helped reduce participant variables such as differences in the ability to recall dreams

How was quantitative data collected?

Brain waves, eye movement patterns, and REM sleep duration was collected through the EEG and EOG.

* These measures are objective and provides a reliable measure since it helps eliminate researcher bias
* Consistent placing of electrodes ensured that recordings from each ppts collected the same info

Weakness of qualitative data collected?

It's subjective and can affect the validity since the narrative length is not only dependent on the REM phase length, but also on the participant's expressiveness.

Why is generalisability limited?

* Small sample of only 9 ppts
* More male than female ppts
* Since individuals chose to participate in the study on dreaming, they may have dreamt more frequently than the general population

How was ecological validity limited?

* People used to drinking coffee/alcohol could’ve have experienced dreams that were atypical for them
* All ppts slept in a lab, where they were connected to machines under observations (different than normally sleeping)

How was ppt WD deceived?

He was misled about the stage of sleep he was being woken in

* Could possibly result in distress and he was unable to provide informed consent

Was confidentiality maintained?

It was since only ppts initials were stated.

Physical protection was adhered to because…

EEGS don’t pose a risk to people

Everyday application:

The EEG allows psychologists to accurately detect dreaming, which can be used to assess people with sleep and dream disorders

Nature vs. Nurture

Nature:

* Collecting evidence from the EEG about brain activity provides direct evidence for the underlying biological processes
* The capacity to dream & underlying emotions in dreams are the product of brain and hormones

Nurture:

* Dream content relates to our experiences, which explains the differences in dreams b/t individuals

Individual vs. Situational

Individual

* Ppts had different success of estimating dream duration

Situational

* Being in the lab could’ve caused strange dreams