Dement and Kleitman (1957) – Quick but Complete Revision Notes

the background to the study

• Study of dreams subjective as it requires relying on reports by participants;
  • Need felt for objective measure of dreaming;

• One previous study used EEG technology to objectively measure which stage sleeping occurs in;
  • Present study employed more rigorous method –
    • no contact between experimenter and participant during dream reporting;
    • establishment of correlation between duration of eye movements and reported length of dreaming;
    • investigation of relation between reported dream activity and direction of eye movement to investigate meaningfulness of activity in dreams

the aim(s) of the study

1. to investigate in which stage of sleep dreaming occurs – REM or nREM stage;

2. to investigate the relationship between duration of sleep and duration of dreaming;

3. to investigate the relationship between direction of eye movement during sleep and direction of activity in dreaming

experimental design –

• repeated measures design

strengths –

• elimination of individual differences;
  • same participants exposed to both stages of sleep, various durations of REM sleep and dream activity of different directions;
  • increased validity

• requirement of lesser number of participants;
  • difficult to find participants for EEG based experiment demanding that participants sleep in the lab for several days;
  • practically more viable

• requirement of lesser number of participants;
  • difficult to find participants for fMRI based experiment;
  • practically more viable

limitations –

• possible fatigue effect;
  • participants had to abstain from coffee and alcohol and sleep in the lab for several nights, being awakened from time to time;
  • this could have disturbed sleep quality or reporting performance with time;
  • possibly reduced validity

• possible demand characteristics;
  • slight possibility of participants understanding the difference between awakened from deep or superficial sleep and reporting dreaming accordingly; 
  • possibly reduced validity

independent variables –

1. stage of sleep;
2. duration of sleep;
3. direction of eye movements

operational definitions

1. measurement of stage of sleep using EEG at two levels –
   1. nREM stage of sleep
   2. REM stage of sleep

2. measurement of duration of sleep using EEG at two levels*-
   1. five minutes of REM sleep;
   2. fifteen minutes of REM sleep

3. measurement of eye movement direction using EOG at two levels-
   1. vertical eye movement ;
   2. horizontal eye movement;
   3. vertical and horizontal eye movements;
   4. little or no eye movements

strengths –

• highly standardized
  • all measurements done precisely with the help of sophisticated EEG and EOG technology;
  • fixed patterns and durations measured for every participant;
  • therefore, highly reliable measurement

• high internal validity
  • measurements done by technology like EEG and EOG have minimum error;

limitations

• difficult to establish cause-effect relationship
  • none of the IVs manipulated by researchers;
  • possibly all only correlates and not determinants of dream related activity

• human error possible in measurement
  • measurement by EEG and EOG machines but recording done by experimenters;
  • possible reduction in validity

*initially, participants were asked to estimate exact duration of dreaming. But since this proved to be too difficult, five and fifteen minute periods were selected which were randomly selected to awaken participants

standardization (selected examples)

• all participants made to abstain from alcohol and caffeine;

• all participants placed in a quiet and dark room for sleeping;

• all participants awoken with a bell;

• all participants made to report having had a dream or not first and then to guess duration of dreaming and narrate dreaming content

the conclusions of the study

the conclusion(s) the psychologist(s) drew from the study

1. dreaming occurs more commonly during the REM stage of sleep than during the nREM stages of sleep;

2. there is a positive correlation between duration of sleep and duration of dreaming;

3. there is a positive correlation between direction of eye movement during sleep and direction of activity in dreaming

consideration of how the study relates to psychological issues and debates

nature versus nurture;

nature

• sleep patterns i.e. nREM and REM stages found in all people;
  • appear to be inherited

• all participants of the study showed at least some dreaming behaviour;
  • same pattern of dreaming and non-dreaming in REM and nREM stages found in all participants

nurture

• differences between participants regarding dream duration, sleep patterns, sleep activity, etc. could be because of personal experiences, health and development, lifestyle, etc.

use of animals in psychological research

• dreaming activity research not possible with animals because of need for self-report;
  • more ingenious research methods required

• EEG sleep pattern studies can be done for simple comparison of human and animal sleep behaviour;
  • to study whether sleep patterns of REM and nREM sleep are unique in humans are found in animals as well