Dement and Kleitman (1957)

• Dement and Kleitman (1957)

  Researchers who studied the relationship of eye movements during sleep to dream activity

  
• Independent Variable (IV)


  The variable that is manipulated or changed by the researcher
• Dependent Variable (DV)


  The variable that is measured or observed for change by the researcher
• Independent Variables


  • REM or nREM sleep
  • Length of REM period
  • Eye movement pattern

  
• Dependent Variables


  • Dream recall
  • Estimate of dream duration
  • Dream content

  
• Sample


  • 9 participants
  • 5 studied in detail, 4 used to confirm results
  • 7 males, 2 females
  • Recruited by opportunity sampling
• Detailed Sample


  • Stayed in laboratory for 6-17 nights
  • Tested/awoken 50-77 times
• Confirmation Sample


  • Spent 1/2 nights in laboratory
  • Tested/awoken 4-10 times
• Procedure


  1. Participants reported to laboratory before usual bedtime

  2. Avoided caffeine/alcohol on day of study

  3. EEG used to record brain activity and eye movements

  4. Participants woken by loud doorbell and asked to describe dreams

  5. Participants returned to sleep

  
• Procedure for Aim 1

  1. Participants woken in REM or nREM sleep (not told which)

  2. Confirmed if having dream and described content

  
• Procedure for Aim 2

  1. Participants woken after 5 or 15 minutes in REM sleep

  2. Chose which duration they had been woken after

  
• Procedure for Aim 3

  1. Participants woken after persistence of single eye-movement pattern for >1 minute

  2. Reported dream

  
• Technique used to measure brain activity was Electroencephalograph (EEG)
• Reason for using EEG

  To amplify and record signals from electrodes attached to face and scalp
• Dream reported with vertical eye movement

  • Climbing ladders and looking up and down
  • Standing at foot of cliff with hoist looking at climbers moving up and down
  • Playing basketball
• Informed consent, deception, confidentiality, privacy, right to withdraw, protection from harm, and debrief were ethical considerations
• This study supports both nature and nurture perspectives
• Findings are based on biological mechanisms, but there could be psychological mechanisms not investigated
• One way the study lacked ecological validity was the laboratory setting
• Two controls used were: participants avoided caffeine/alcohol, and participants were woken by a loud doorbell
• The laboratory setting was appropriate to allow high levels of control and standardisation
• The doorbell control was used to wake participants at specific times during sleep stages
• Two features of the sample were: 9 participants total, with 7 males and 2 females
• A weakness of the sample was the small size and gender imbalance, reducing generalisability
• An EEG measures electrical activity in the brain
• A limitation of using an EEG is that it only measures biological mechanisms, and may miss psychological factors involved in dreaming
• Specifically, they wanted to investigate:

  1. Does dream recall differ between REM and nREM stages of sleep
  2. Is there a positive correlation between subjective estimates of dream duration and the length of the REM period before waking?
  3. Are eye movement patterns related to dream content?
• Electroencephalograph (EEG)


  Machine that can detect and record minute changes in voltage associated with electrical activity in nerve and muscle cells
• Electro-occulograph (EOG)


  EEG used to record the frequency of eye movements
• Independent Variables


  1. Occurrence of Sleep Stage (REM or nREM)

  2. Duration of REM Sleep (5 or 15 minutes)

  3. Pattern of Eye Movement during REM Sleep (mainly vertical, mainly horizontal, both vertical and horizontal, very little or no movement)
• This study was a laboratory experiment

  • High levels of control over variables but may lack ecological validity
• The data collected was mostly quantitative


  • Relatively easy to collect and analyze statistically, but reduces complex qualitative phenomena to numbers
• The data collected about dream content was more qualitative


  • Gives richer and more interesting data but difficult to use for comparisons and hard to analyze statistically
• The sample was very small (9 participants, 5 studied intensively)
• The research studied participants who went to sleep in a laboratory with electrodes stuck to their heads, which is unlikely to bear much relation to normal sleep
• Participants were woken up several times during the night and asked about their dreams, which is unlikely to happen normally and may have had an effect on the way they slept
• The conclusions that were reached by Dement and Kleitman have been replicated by many other researchers
• Dement and Kleitman's research really did add new information to what was known about sleep and the use of EEG to record brain activity whilst sleeping was relatively new at the time