♥Core Studies| Physiological Psychology| Dement and Kleitman (1957) Dream and Sleep♥

Dement and Kleitman (1957)| the Relation of Eye Movements during Sleep to Dream Activity

Dement and Kleitman studied how the stage of sleep you are in affects whether you can or can't recall your dreams.

Background to the study 

Sleeping consists of a number of stages-which can be shown by the different patterns in alpha and beta waves during a test called electroencephalography; which is a method of measuring different electrical activity in the brain by recording from electrodes which will be placed on the scalp. Electroencephalography can also be referred to as an (EEG).

Overall there are four stages of sleep:

Stage One is the lightest stage of sleep (by lightest I mean the easiest to wake a person up from), you can characterise it by a lowered heart rate, relaxed muscle tension and a lover body temperature. Really this is when the body begins a state of relaxation. This stage is represented by slow alpha waves that have a frequency between 8-12 Hz per second.

Stage Two is still light but deeper than stage one, a person can still be woken up relatively easily and this is represented by larger EEG waves and spindles (which are bursts of high frequency waves between 12-16 Hz)

Stage Three is a deeper sleep, the waves are now delta waves which are large and slow waves between 1-3 Hz, in this stage people don't respond to external stimuli such as a light switching on or a car alarm going off and are quite difficult to get up.

Stage Four is the deepest sleep, people in this stage of sleep will respond to personal stimuli such as their baby crying, their metabolic activity is also low. This stage is characterised by delta waves of 1 Hz.

It takes around 30 mins to get down to stage four sleeps. When at stage four you spend 30 mins in this stage and then we fluctuate between stages 3 and 2 but instead of re-entering stage 1 again we go into a phase called Active Sleep. This stage is represented by much desynchronised pattern similar to that if we were awake. In this stage our metabolic activity increases along with heart rate but the body is still more or less paralysed and this stage makes waking up a person an impossible task. This phase of sleep is referred to as the deepest stage called REM sleep (which stands Rapid Eye Movement) this is because you can observe the movement of your eyes in this stage under closed eyelids. We tend to spend 10-15 mins in REM sleep and then go back to stage 4, 3, 2 etc. This cycle takes about 70-90 mins to happen and is repeated 5-6 times a night.

A restoration theory suggests that non REM sleep restores bodily processes that have deteriorated during the day. Whereas REM sleep stimulates protein synthesis which replenishes brain processes. Sleep can be described as a survival function by keeping animals safe from predators, and hibernation can be seen as an extension of this process.

You might wonder why is it that we dream, well there are many theories that relate to just that question. Reorganisation of mental structures theory suggests that REM sleep is involved in the organisation of schemas which is the cognitive structures that support cognitive processes. This is supported by the finding that complex cognitive tasks lead to an increase in the time spent in REM sleep and also by the fact that babies spend so much time in REM sleep. IN other words it can be said that REM sleep is seen as a support of cognitive development. The Activation Synthesis Model proposes that dreams are the 'active interpretation of the signals produced by the cortex during REM sleep. Crick and Mitchinson (1983) suggested that this is a way of us being able to sort out all of the information that we absorbed that day so dreaming is something which allows our brain to decide what information we want to keep or get rid of. And finally Freud (1900) saw dreams as the 'royal road to the unconscious' and psychoanalytic therapists still use dream interpretation as a way  of interpreting individual patients hidden desires and thoughts.

Aim 

Aim of the study was to investigate the following three hypotheses:

Hyp 1- There will be a significant association between REM sleep and dreaming - which basically asks the question whether we dream in REM sleep.

Hyp 2- There will be a significant positive correlation between the estimate of the duration of dream and the length of eye movement- so this is asking whether our eye movement has anything with dreaming,

Hyp 3- There will be a significant association between the pattern of eye movement and the context of the dream- which is basically proposing that the direction in which we move our eyes associates the directions were looking in our dreams.

Participants 

The participants consisted of 9 people. The sample was studied in two groups, a group of five participants who were studied in depth and a group of four participants who were used as a control group (meaning that they were used for a comparison)

The sample was made up of 7 men and 2 women, although not confirmed it is suggested that there was one woman in each group.

Procedure

Sleep sessions took place in a 'sleep lab' that was set up for the experiment- which meant that participants were in a set up environment. Participants could eat normally but were told to not drink caffeine or alcohol on the day of the study- this took place so that any extraneous variables which could disturb the natural sleeping pattern of the participants. EEG electrodes were then placed near the eyes to measure the electric to measure electric activity and therefore REM (Rapid Eye Movement). From this D&K could know when a participant was in REM and what type of REM they were in. Electrodes were also placed around the skull so D&K could measure the brain activity of the participants.  The participants were then woken at various times in the night using a doorbell that was situated by their bed and were asked to record their dreams (if they remembered anything from them) on a voice recorder. Sometimes participants were woken during REM sleep and sometimes they weren't woken during REM sleep. If no dream were recalled it got recorded as a ''no dream''. Five out of nine participants were studied over a period of 61 nights with 351 awakenings in total and an average of 5.7 awakenings per night.

Testing Hyp 1:

Participants were woken up during the night with a loud doorbell sound, and then the participants had to speak into the voice recorder. They were then instructed to first state whether or not they had been dreaming and then, if they could remember the dream they would recall their dream. The participants were only reported as having dreamed if they could coherently recall their dream (give loads of detail about the dream). Participants were woken up on a schedule so one participant would be woken up three times in REM and then three times in N-REM so on, Two were woken up at random, One was told that he would only get woken up in REM but got woken up randomly. Another was woken up at the experimenter’s whim. To eliminate experimenter effects, the experimenter did not communicate with the participants during the night, and also to eliminate bias the participants were not told whether their eyes moved or not.

Testing Hyp 2:
The participants were also woken at either 5 or 15 mins into REM sleep and were asked to predict whether they had dreamt for 5 or 15 mins.

Testing Hyp 3:

The participants were woken up as soon as one of the four patterns of eye movement had lasted for at least one minute. On waking the participants were asked to describe in detail the content of their dream. The four patterns that prompted an awakening were: mainly vertical eye movements, mainly horizontal eye movements, both vertical and horizontal eye movements, very little or no eye movement.

Findings

All participants showed periods of REM every night during sleep. The REM EEG was characterised by a low volt. And relatively fast pattern which were characteristics of a deeper sleep. (Refer to your graph and background to the study to look at patterns of REM). REM never occurred at the beginning of the sleep cycle. REM periods which were not terminated by an awakening varied between 3 and 50 mins with a mean of about 20, and tended to increase in length as the night progressed. REM periods occurred at regular intervals during the night, though each participant has their own pattern: mean period of REM phase for the whole group was 92 mins, with individual norms varying to between 70-104 mins.

Hyp 1: in REM sleep 152 dreams were recalled in comparison to 39 dreams that weren't recalled. In N-REM sleep 11 dreams were recorded in comparison to the 149 dreams that weren't recorded. So this shows that that REM sleep is predominantly- but not exclusively- associated with dreaming. When participants were woken up at 11 mins into REM so the transition to N-REM they could remember distorted bits of information from their dreams.

Hyp 2: results to the estimates of the length of dreams were five mins into REM 45 participants correctly guessed the length of their dreams where as 6 didn't. When fifteen mins into REM 47 participants correctly guessed the length of their dream where as 13 didn't. Which suggests that all participants could correctly choose the correct dream duration fairly accurately? 

Hyp 3: There did appear to be some relationship between the dream content and the type of eye movements. After a series of vertical eye movements dreams such as: standing at the bottom of a cliff operating a hoist, and looking up at the climbers and down at the machinery, climbing up a series of ladders looking up and down, throwing basketballs at a net, first shooting and looking up at the net, and then looking down to pick another ball off the floor. Horizontal eye movements recorded such dreams such as watching two people throw tomatoes at each other. When a mixture of eye movements were recorded dreams involved looking at people or objects close to them. Little or no eye movements recorded dreams when a person was watching something from a distance or just staring fixedly at some object. In order to confirm the meaningfulness of the results of the relationship 20 naive and 5 of the experimental participants were asked to observe distant and close-up activity while awake. These measurements were in all cases comparable to those occurring during dreaming.

Evaluation 

The strength of this method is that it is high in reliability as such studies as this can be repeated by other researchers, And also it took place in a highly controlled environment which meant that any extraneous and confounding variables are ruled out. However it laced in ecological validity as none of the participants had a natural sleep because of being placed in unnatural settings and wouldn't sleep with electrodes placed on their head, but it could be looked over if the study might actually happen if the participants were in their own bed it might alter the sleeping pattern, 

The sample was un-repersentable with a ratio of 7:2 for males to females which is a significant gender imbalance. But this has been overcome by the amount of overall awakenings which summed up to 375 awakenings. As the physiology of the brain is similar in all people we don't need a large sample which is why the sample size is ideal. Both Qualitative and Quantitative data was used; quantitative data was collected by the means of the EEG \and Qualitative data was collected via the description of the dreams. The study was useful as it allowed us to see if there was any correlation between sleep and our eye movement. However it’s not a general sable study as it did take place in controlled conditions therefore its usefulness can be argued.

It is a reductionist study as it gives a biological explanation of the narrow focus, which is that dreaming is simply a product of REM sleep.

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Hope this was helpful. If you have any question please ask and as the exams aren’t far away id encourage past papers for region purposes which for this course can be found on the OCR Website: Core Studies Past Papers Code G542 and Psychological Investigations code is G541