Biological Approach (Dement And Kleitman)


Psychology 9990

Biological Approach (Dement And Kleitman)

Biological Approach (Dement And Kleitman)

Biological Approach (Dement And Kleitman 1957)

An Objective Method For The Study Of Dreaming” The Relation Of Eye Movements During Sleep To Dream Activity:

While investigating the topics of sleep and dreaming have been difficult throughout the times because of factors such as no communication with the researcher and thus no control over what becomes of the data. This is evident as the only way to actually collect data is self-reports, but these have hindered validity due to them being merely anecdotal evidence and highly subjective. 

The study became more scientifically rigorous with new inventions and innovations of physiological techniques that measure brain activity that indicates that dreaming is happening and allowed the electrical documentation of eye movements rather than their direct observation.  These techniques were utilized by Dement and Kleitman to track and monitor the cyclical changes that happen in brain activity and eye movements during a sleep period in a night. 

It was in 1955 that the usage of an ‘electroencephalograph’ was applied to record brain activity and eye movements that showed that we have several stages during the night where we alternate between REM (Rapid Eye Movement) and nREM (Non-Rapid Eye Movement). It was reported that participants waking up from a REM sleep were more likely to report a vivid, visually visceral dream as compared to waking up in different stages. 

This device (an EEG machine) detects and records minuscule electrical charges associated with nerve and muscle activity.  Th EEG machine produces a chart that shows changes, brain waves in the chart record to indicate the sleep stage a person is in. These change with the frequency and amplitude of electrical output from the brain over time. An EEG can also be used to detect activity in the muscles that move the eyes, measuring eye movements. 

EEG patterns in REM sleep are low voltage, high amplitude waves. Whereas in, nREM sleep has either high-voltage or slow waves or sometimes what is commonly known as “sleep spindles”, which are short-lived high-frequency waves. 

The EEG electrodes/machines can also be used to record eye movements. The input is however called an electrooculogram indicates the presence or absence of eye patterns, cycles and movements. Factors to consider are: size, direction, duration, etc. 

Explaining The Sleep Cycle: 

Throughout the sleep cycle progresses into different stages throughout. Aspects such as heart rate and brain activity. In a night of normal uninterrupted sleep, we venture through these stage about 4-5 times and the normal estimated time for a cycle to be completed takes 90 minutes. 

There are apparently 5 stages of sleep, with first 4 stages being n-REM: 

N-REM 1: 

- This is the stage between wakefulness and sleep, being the lightest stage. 
- Alpha waves (which are low voltage waves) are produced, this is found out via EEG scanning. 
- It is possible for an individual to experience strange sensations, that aren’t physically present. Sensations such as bells ringing, name calling are common. 
- Sensations of previous experience are also likely to reoccur. Such as an instance if a person was rowing or swimming all day, the person is likely to experience that movement in the sleep cycle. 

N-REM 2:

- This is the deeper level where the possibility of waking a person up in harder. 
- Sleep waves are shown by EEG scans in the form of ‘sleep spindles’ (bursts of rhythmic brain activity) and k-complexes (large waves that are distinct and occur due to atmospheric stimuli such as loud noises).
- These sleep waves are the reason why sleep is deeper. 

N-REM 3 AND 4:

- During these stages the breathing rate, heart rate and brain activity decrease substantially. 
- Consists of large amplitude waves.  Also known as “Slow-wave sleep”. 
- Consist of waves known as ‘Delta waves’.
- No possible consciousness. People usually walk and talk in this stage of sleep. 

REM Stage: 

- This is the stage where our eyes move very rapidly underneath our eyelids. 
- Dreaming occurs in this stage, exclusively. 
- Muscles are physically paralysed, which is a positive sign. The brain is most active at this point, whereas the body as at total rest. 

The Psychology Being Investigated: 

- This study investigates the sleep stage and the dreams that occur. 
- The duration of a dream during REM stage. 
- The patterns of eye movement during REM.
- The direction of movement and the correlated content of the dream. 


While in essence the aim of the study is to investigate dreaming in a more objective way by looking for relationship between eye movements in sleep and the recall of the dreamer. 

The aim of the study can be dissected into 3 parts: 
- Aim 1: Does the dreamer’s recall differ during the stages of nREM and REM?
- Aim 2: Does a positive correlation exist between the subjective estimates of dream period and the span of the REM cycle? 
- Aim 3: Does the occurrence of difference in patterns of eye movement in REM relate to the content of the dream? 


- The study was conducted in a laboratory with varying designs: 
- 3 approaches were used to test the given aims. 
- For Aim 1: 
- IV: REM AND NREM Stages.
- In this, participants were woken either from REM or nREM sleep, but they were not informed as to in which sleep state they had been woke from. They confirmed if they were dreaming, with them giving a descriptive account of the dream into a recorder. 
- For Aim 2:
- IV: 5 minutes or 15 minutes.
- In this, participants were woken in after either 5 minutes and 15 minutes in REM sleep. The participants in question were asked to estimate if they had dreamt for 5 minutes and 15 minutes. (Longer REM periods were also examined). They were again asked to record the account of their dream and the number of words in the dream account was counted. (This was because qualitative result would increase qualitative valence). 
- For Aim 3: 
- IV: Directions – 1. Mainly vertical, 2. Mainly horizontal, 3. Both vertical and horizontal, 4. Very little or no movement. 
- In this, participants were investigated upon the basis if the patterns in dreams, directions (vertical or horizontal) represented visual experience of the content of the dream or if they were just randomized, investigating the activation of CNS (Central Nervous System) during sleep. The direction of the eye movements were recorded using electrodes. Participants were then woken up if a single patterned eye movement was occurring for more than 1 minute. They were again asked to give an account of their dream. 


Sampling of participants: 
- Sample size: 9 adult participants – 7 males and 2 females (making it an androcentric sample) 
- 5 participants were studied in detail while the remaining 4 were used to confirm the data obtained from former 5. 
This experiment was carried out via 3 respective studies:

Study # 1: This was natural experiment in a lab setting. 
- IV: Whether participants woke up from REM sleep/nREM sleep. 
- DV: If a dream was reported. 
- A repeated measures design was used. 

Study # 2: Relationship between dream period and duration of REM timespan as a correlation. The comparison between estimates of dream period (5 minutes or 15 minutes was another repeated measures design). 
- Experimental analysis:
- IV: Participants waking up either 5 mins or 15 mins.  
- DV: Participants choosing to say either 5 mins or 15 mins. 
- Correlational analysis:
- Number of words in the dream narrative. 
- Participant’s time estimate. 

Study # 3: 
- IV: Eye movement pattern
- DV: Dream content. 
- A self-report measure used. 


- The 5 important participants utilized, had to spend 6-17 nights in the laboratory, with a total of 60-77 awakenings taking place throughout the procedure. 
- The 4 non-important participants utilized, had to spend 1-2 nights in the laboratory, with a total of 4-10 awakenings taking place throughout the procedure. 
- Each participant was identified via a pair of initials, maintaining confidentiality. 
- Pre-requisites taken to control variables before entering the experiment: 
- Complete avoidance of alcoholic or caffeinated beverages. 
- A normal diet pattern. 
- The experimental setup consisted of the participants arriving before their usual bedtime and were fit with apparatus that would record data. With the electrodes attached near the eyes and the scalp. 
- This was conducted in a quiet, dark room.
- This however also exposes the study to low mundane realism and low ecological validity. 
- Logistical adjustments such as allowing freedom of movement for the participants was done by gathering the wires from the electrodes into a “ponytail”. 
- The EEG ran constantly throughout the night to monitor the sleep stages of each participant. 
- They were proceeded to be woken up by a doorbell which was loud enough to wake them from any stage of sleep, with the researcher not having to enter the room, avoiding unnecessary contact. This prompts standardization. 

Does The Dreamer’s Recall Differ During The Stages Of nREM And REM?

Procedure for Study # 1Results of Study # 1

  • Participants were either woken up from REM and nREM sleep but were not informed from which. 

  • This was decided in a variety of ways for different participants, revolving around standardization. 

  • The participants were also labelled via their initials in an effort to maintain confidentiality. 

  • A random number table was used, where participants PM and KC were allocated. 

  • In groups of 3 nREM and 3 REM participant DM was allocated. 

  • In a randomized fashion, experimenter allocated participant IR. 

  • Deception – Participant WD was told he/she would be woken up in REM but in actuality was woken up randomly. 

  • After the participants had been woken up, they were asked whether or not they had a dream. If yes, they were asked to describe the dream and give a detailed account of it into a recorder. 

  • It is important to note that the number of words used, had significance because the larger number of words determined the account to be more detailed and in-depth (qualitative data). 

  • While there was primarily no contact between the experimenter and the participants (in an effort to reduce researcher bias and subjectivity), there was occasionally some questions that were asked by the experimenters to the participants. 

  • Participants described dream more often when they woke from the REM stage of sleep. 

  • Participants described dreams rarely when woken from nREM stage of sleep. When they did describe dreams, it was more emotions/feelings rather than dream content/cognitive visuals. 

  • This was a consistent pattern. The waking pattern however did not affect recall. 

  • For instance, participant WD was accurate despite being misled. Whereas, participant was no more accurate, even if he/she might have had guessed the pattern of the awakenings schedule. 

  • When the participants were woken during REM stages 3 & 4, (which is a high voltage, slow-wave period) - they looked bewildered/ confused. 

  • They also said they ‘might’ have been dreaming, but they could not remember the content of their dream. 

  • When the participants were woken from nREM stages, they tended to retract into nREM stage, with the next stage of sleep being REM with no delay. 

  • The exception here was when a participant was woken from their final REM phase of the night. If so, they tended to fall back into REM after the awakening. 

  • Therefore, it could be concluded that REM and nREM stages differ. 

  • In REM visual, vivid and clear dream content was reported. During the awakenings and a little while after it.

  • Whereas, in nREM it was it was vague. 

Does A Positive Correlation Exist Between The Subjective Estimates Of Dream Period And The Span Of The REM Cycle?

Procedure for Study # 2
Results of Study # 2
  • The participants were woken up after either 5 minutes or 15 minutes. 
  • This was during REM stage.

  • The participants had to guess actually how long they think was the duration of their dream. 
  • The number of words in their account of the dream, was counted. 

  • The participants were woken up after several REM periods and were asked to estimate the length of these. 

  • It did however prove quite tedious and difficult for the participants. 
  • The task for them then was reduced to pick their answer as either 5 minutes of REM or 15 minutes of REM, which proved to increase the accuracy and volume of answers.
  • For 5 minutes – 88% were accurate in their task. 
  • For 15 minutes – 78% were accurate in their task.
  • While most were accurate, one wasn’t - participant DN. He only was able to recall the end of his dream, and thus the dream itself was shorter as per account. 
  • DN thus chose 5 minutes more frequently and consistently which raised a question to the findings’ validity. 
  • However, this did prove that DN was accurate on estimates of 5 minutes instead of 15 minutes, in REM.
  • In total narratives from 152 dreams were collected.  (26 were however not used because they were poorly recorded.)
  • Word count was maintained (standardization and reliability factors in.)
  • While the variable of the participant being articulate/expressive did exist and vary respectively – a significant positive correlation was found between number of words in the narrative/account by the participant and the duration of the REM. 
  • R values varied on a scale of 0.4 - 0.7 for different participants. 
  • The account of the dream narratives for very prolonged dreams were not much longer or extensive than those for 15 minutes. 
  • The participants reported however, feeling as if they had dreaming for quite a long time, with a vagueness in recalling the earlier part of the dream. 
  • The sleep duration for these participants was around 4.2-7.5 hours.

Does The Occurrence Of Difference In Patterns Of Eye Movement In REM Relate/Represent To The Content Of The Dream?

Procedure for Study # 3
Results of Study # 3

  • EEG electrodes were placed around the eyes, to detect and document the direction of eye movements. 

  • Participants were woken up after a particular/single pattern of eye movement had lasted for more than 1 minute and then they were asked to report their dream in detail. 

  • The patterns of eye movement were:  

             1.  Mainly vertical

             2. Mainly Horizontal 

             3. Both vertical and horizontal 

             4. Very little or no movement 

  • The researchers found that participants’ accounts were not adequately accurate to be matched exactly to the changes in the patterns of eye movement. 

  • A total of 35 awakenings were analysed further. 

  • 3/9 participants showed periods of predominantly vertical eye movement, where each connected to a narrative about vertical movement.

       -  In one, the participant dreamed about standing at the foot of a tall cliff, using a hoist. The participant reported looking up at climbers at various levels on the cliff and down at the hoist machinery. 

       -  In another one, a participant’s dream revolved around them climbing up a series of ladders and looking up and down while climbing. 

       -  In a third dream a participant was playing basketball, shooting at the net and looking up to see if he had scored the looking downwards to pick up another ball. 

       -A single-dream followed predominantly horizontal movements – the participants reported dreaming about two people throwing tomatoes at each other. 

  • On ten occasions participants were woken up after little or no eye movement. They reported either watching something in the distance or staring with their eyes fixed on a singular object. 
  • In two cases, the participants had dreamed about driving. The movement of their eyes was very still and then made several sudden movements to the left just before being woken up. 
  • To configure mixed eye movements, 21 awakenings followed. These findings confirmed that, when awake our eyes are relatively stable when we are focused on objects in the distance and show movements of similar amplitude to when we are dreaming of viewing nearby objects. 
  • Few vertical movements were recorder except when the researcher threw a ball in the air for participants to watch.
  • Other findings/results suggested that REM durations lasted from 3-50 minutes with an aggregate of around 20 minutes.
  • The amount, pattern and size of REM phases ranged and varied from duration to duration. The REM periods were at fairly regular intervals but individually specific. 

       -  For example: 

       -  Participant DM averaged 1 REM phase every 70 minutes. 

       -  WD 1 every 75.

       -  KC 1 every 104. 

       -  The aggregate for the entire group was 1 REM phase every 92 minutes. 


- It is plausible that dreams occur regularly throughout each night’s sleep. 

- Dreams reported when woken up from an nREM episode are actually previous REM episodes. 

- As the REM phases are more prolonged in the night, dreaming is more likely to occur at this point in time. It is also important to consider how dreams do not necessarily occur every night. 

1) A, If previous recordings were not continuous/consistent, they may have failed to catch instances of dream sleep in exclusively every participant.  

2) B, The equipment might have missed out/neglected small movements that might be pivotal to the conclusivity of the results. 

3) C, Participants who ‘did not dream at all’ might have experienced dreams that simulated fewer and small-scaled eye movements, such as those of distant and stationary objects. 

- It is widely believed that dreams happen in an instant. Therefore, if the length of REM periods is proportional to subjective estimates. This would help strengthen the belief that the two are linked/related and would provide information about how the dreaming progresses. 

- The finding that the duration of an REM period and its estimation by the participant are very close shows that dreams are not instantaneous events but rather they are experienced in ‘real time’. 

- Eye movements during REM sleep correspond to where and at what the dreamer is looking in the dream. This propagates the notion that eye movements are not plainly random events caused by the activation of the CNS, but related directly to dream imagery and visuals.

- Moreover, they correspond in amplitude and pattern to those we experience when we’re awake. 



  • Measures to collect was objective and scientific, which increases validity. (EEG machines).

  • There was no significant stress, injuries or harm caused to the subjects involved. 

  • The study was highly controlled as variables such as researcher bias, undisturbed sleep atmosphere, etc.

  • The research method used (repeated measures design) was highly useful because each participant had different, various dream which if RMD had not been used would have been difficult to compare the occurrence of the dream and analyse them accordingly. 

  • The measure of self-report (account given by participants of the dream) was subjective and thus may have social desirability and demand characteristics. 
  • The sample size was small, androcentric (with only 2 females) and non-generalizable. 
  • Subsequent studies have found that there are large differences between individuals in the reports of dreaming during REM. 
  • There was no background check of the participants (may be ethnocentric.)
  • There may have been experimenter’s influence during the waking of the participants, which might have affected their ability to recall their dreams. 
  • Ethical regards are unknown – in regards to right to withdraw and informed consent. Deception also took place. 
  • The validity and credibility of the study is challenged when it is taken into perspective, the setting of the experiment - in a laboratory. 
  • This means low ecological validity and low mundane realism, which might have affected the study’s findings in the larger scale. This includes dream content, directions of eye movement, ability to recall dreams and duration of estimated subjective time periods of dreaming. 

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