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 # 1||Results of Study # 1|
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|
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|
Conclusions:- 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.