Aim:
To investigate dreaming in an objective way by looking for relationships between eye movements in sleep and dream recall.
Method:
Three approaches used to test aim: REPEATED MEASURES DESIGN
1.Whether dream recall changes between REM and NREM sleep (Natural experiment in laboratory setting)
- IV = REM and non-REM sleep.
- DV = whether a dream was reported.
- Participants were woken up, not told what stage they had been in.
- They confirmed whether they had been dreaming and tell its content.
2. Whether subjective estimates of dream duration are related to length of REM period (True experiment)
- Experimental design: IV= waking after 5 or 15 minutes. DV= participant’s choice
- Correlational analysis: IV = participants’ time estimate DV= number of words in narrative of dream.
- PPs were woken up following 5 or 15 minutes in REM sleep, asked how long they thought they were sleeping for, report of dream content and number of words counted.
3. Whether eye movement patterns represent visual experience of dream content or whether they are random movements from activation of central nervous system.
- IV = eye movement pattern type (not manipulated by researchers, so natural experiment)
- DV = report of dream content.
- Eye movement detected using electrodes around eyes (EOG).
- PPs woken up after exhibiting a single eye-movement patter for no longer than 1 minute.
- Asked to report their dream.
Participants:
Nine adult participants (7 males and 2 females):
- 5 studied in detail, spent 6-17 nights in laboratory (50-77 awakenings).
- 4 used to confirm data, spent 1-2 nights (4-10 awakenings)
- Identified with initials.
Procedure:
Day prior to study, PPs could not drink alcohol or caffeine.
They arrived at laboratory before their bedtime – fitted with electrical recording apparatus.
Wires were gathered into pony tail to allow freedom of movement.
PPs woken up by a doorbell – said if they were dreaming and described the content into a voice recorder.
Returned to sleep within five minutes – Experimenter may enter the room to ask questions
Coherent, detailed description = dream
PM and KC – waking determined randomly.
WD – randomly woken up, but told he would only wake for dream sleep.
DN – woken up on patter of 3 REM followed by 3 NREM.
IR – chosen by experimenter.
Results:
Approach 1:
- Participants described dreams often (152 out of 191) when woken in REM but rarely from NREM (there were 11 of 158)
- NREM tended to describe feelings.
- Recall of dream after NREM was more likely if they were woken up soon after REM sleep ended.
Approach 2:
- 88% accurate for 5 minutes waking.
- 78% accurate for 15 minutes waking.
- Narrative from 152 dreams were collected – 26 too poor record.
- Positive correlation between REM sleep and number of words.
Approach 3:
- Participants’ narratives were not accurate enough to be matched to eye movement changes.
- 3/9 showed periods of vertical eye movements = narrative of vertical movement.
- 1 dream followed horizontal movement.
- 10 occasions – PPs woke up after little or no movement = watching something in the distance or staring.
- 21 waking after mixed eye movements – looking at things nearby.
When woke up from NREM, participants returned to NREM – next REM stage was not delayed.
When woken up from REM, they did not dream until next REM stage
Conclusion:
- Dreams probably occur only during REM sleep. Dreams reported from NREM are from previous REM stages.
- The length of REM periods is proportional to subjective estimates, this would help to confirm that they are related and would provide information about the rate at which dreaming progresses. Therefore, the findings show that dreams are not instantaneous events but they are experienced in “real time”.
- Eye movements during REM sleep correspond to where and what the dreamer is looking at in the dream. Therefore, they are not random events caused by the activation of the central nervous system during dream sleep, but they are related to dream imagery. Also, they match in amplitude and patter to those experiences when awake.
Strengths:
- High level of control – the researchers controlled many extraneous variables such as not drinking alcohol or caffeine before the experiment, waking up participants with the same doorbell sound and having participants in the same environment. This makes the results valid and reliable.
- Replicable – the procedures were standardised since it was a laboratory experiment and scientific equipment was used. This makes the study easier to replicate and check for the reliability of results.
- Ethics – researchers gained informed content from all the participants, who had the right to withdraw the experiment at any time if they felt uncomfortable or did not want to continue. Also, the identity of the participants was kept private, by using initials.
Weaknesses:
- Low ecological validity – the environment were participants were studied was artificial i.e. they slept in a laboratory with electrodes on their head and face and were woken up by a doorbell. This may have affected the results as it could have caused demand characteristics and the realism of the study was lowered.
- Low generalisability – the results cannot be generalised to the wider population because only 9 people were studied, therefore the sample was too small and the result may have been individual. Also, there was no diversity in age, ethnicity and sex.
- Correlation – the results were drawn up by using correlation, therefore the researchers cannot identify the cause and effect of them. Only a relationship was found, but the nature of it is unclear.
CIE A Level Psychology 