Unit 2: Biological Approach Assumptions of the Biological Approach Behavior ,cognitions and emotions can be explained in terms of the working of the brain, effects of hormones ,genetics and evolution. Similarities and differences between individuals can be explained in terms of biological factors and their interaction with other factors Core studies under the Biological approach Dement and Kleitman ( sleep & dreams) Hassett et. Al (Monkey Toy Preferences) Holzel et.al (Mindfulness & Brain Scans) Dement & Kleitman (Sleep &Dreams) Background Kleitman conducted sleep research using his relatives as participants for many years. In 1953, his student, Aserinsky, used an EEG to identify REM and NREM sleep. Kleitman and Aserinsky also found that people woken in REM are more likely to report dreams than those woken in NREM. Dement and Kleitman wanted to find a reliable and objective way(EEG) to measure whether a person is dreaming, using biological evidence rather than verbal self-reports THE PSYCHOLOGY BEING INVESTIGATED Sleep: During sleep, the body is inactive. Conscious awareness is temporarily halted. Five sleep stages have been identified using electroencephalography (EEG). Each stage is characterised by differing brain-wave activity. Stages 1 and 2: light sleep; easily woken. Stages 3 and 4: deeper sleep; brain waves have higher amplitude and lower frequency than brain waves in stages 1 and 2. Rapid eye movement (REM) sleep: lower amplitude/higher frequency brain waves, similar to wakefulness; the eyelids move quickly but other muscles are paralysed; dreaming is common. Ultradian rhythms Ultradian rhythms are bodily cycles that repeat more than once every 24 hours. During the night, we move through several 90-minute sleep cycles. Earlier in the night, the cycles include a higher proportion of nREM sleep. Later in the night, we spend more time in stages 1, 2 and REM sleep. Dreams:are subjective memories of our experiences during sleep(vivid sequences of imagery) Dreams are difficult to study as no machine can read our dreams. Aims of the study To investigate the following questions: 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? Research Method & Design ,IV & DV: Aim 1: Method: Laboratory experiment Design: repeated measures design IV : REM sleep & nREM sleep DV: Dream recall Aim 2: Method: Correlational study Design: repeated measures IV: duration between 5 or 15 minutes DV: participant’s estimate + number of words in dream narrative. Aim 3: Method: self –reports(interviews) IV: Eye movement pattern operationalized as (vertical, Horizontal, both V & H, Little or no eye movement) DV: Dream content Features of the sample Adults 9 in total 7 male 2 female 5 were studied in detail 4 were used to confirm the results Procedure(General) Participants arrived at the lab just before their normal bedtime. They slept in a dark, quiet room. Electrodes were attached beside the eyes and on the scalp. The wires fed into the experimenter’s room. They were gathered into a pony tail so that participants could move easily in bed. They were woken by a loud door bell at different times during the night. They were then asked to describe their dream if they were having one. They went back to sleep. They were not told whether their eyes were moving. Procedure(Aim 1) Participants were woken from REM or nREM sleep. They were not told which Immediately after being woken,they stated whether they had been dreaming or not. If dreaming, they described the content of the dream into a recorder. Once done,the experimenter occasionally entered the room to interview the participant. There was no other communication between the experimenter and participants to reduce the risk of investigator effects. Participants PM & KC were woken using a random number table. DN was woken in a pattern of 3 REM then 3 nREM periods WD was told he would only be woken in REM but was actually woken randomly either in REM or nREM IR was woken in no specific order Procedure(Aim 2) Participants were woken after a variety of REM durations They were asked to estimate how long they had been dreaming, being woken after either 5 or 15 minutes in REM sleep. The participant guessed the duration they had been dreaming for. Longer REM periods were also recorded. Number of words in the dream narrative was given. Procedure(Aim 3) Participants were woken after a single eye movement pattern had lasted for more than a minute and asked to report their dream Eye-movement patterns were: Mainly vertical Mainly horizontal Both horizontal & vertical Very little or no movement Controls Participants all: abstained from alcohol and caffeine on the day of the study reported to the laboratory at their normal bedtime. » The same loud doorbell was used for all awakenings. » The positioning and number of electrodes was standardized (2–3 near the eyes and on the scalp). The experimenter interviewed the participants after they had completed their recording to reduce the risk of investigator effects Results(General) Participants dreamed every night Uninterrupted dream stages: lasted 3-50 minutes Were typically longer later in the night No rapid eye movements were seen during the onset of sleep Results(aim 1) Participants described dreams when woken from REM but rarely from nREM sleep Participants recalled dreams from 79.6% awakenings from REM Participants did not recall a dream from 93.1 % of awakenings from nREM In nREM participants tended to describe feelings but not specific dream content. Partcipant DN was no more or less likely to report or not report dreams in REM or nREM than other participants Awakenings in REM sleep did not always produce dream recall especially in early in the night Results(aim 2) Participant’s choice of estimating dream duration was very high in accuracy:88 % accurate for 5 minutes and 78% accurate for 15 minutes There was a significant positive correlation of duration of REM period and number of words in the dream narrative: r=0.4 – r= 0.71 Narratives from dreams recalled after 30-50 minutes of REM were not much longer than those after 15 minutes Results (aim 3) Eye-movement patterns were found to be related to dream content Periods of only vertical or only horizontal movements were very rare. Conclusion Dreaming is experienced in REM but not in nREM sleep. Participants can judge the length of their dream duration. REM patterns relate to dream content. Dreaming is more likely at the end of the night, as REM stages are longer Strengths Since a laboratory experiment was used, the effect of some uncontrolled variables were limited. Therefore, we are more confident that it was the IV directly affecting the DV, thus increasing internal validity. For example if participants in different sleep stages had woken more slowly, they may have forgotten more of their dream, as a control, a loud door bell was used to wake them up instantly from any sleep stage. The definition of a dream was clearly operationalized as a recollection of content rather than just feelings and emotions. This helped in raising validity as the researchers could be sure that the details being recorded were of dreams EEG is an objective way to investigate dreaming as it is a biological measure. It is reliable because it is not affected by the experimenter’s personal view A standardized procedure including the consistent placing of electrodes ensured that recordings from each participant would provide same information. This can be replicated by other researchers to check for reliability. Participants were referred to by their initials, this followed the ethical guideline of confidentiality Weaknesses. Since the study used only 9 participants, the sample size was too small and therefore the findings had low generalizability.Furthermore,since they had chosen to take part in the study, they may have dreamed more frequently than the population in general, remembered their dreams better or even had more visual dreams. Sleeping in a laboratory, connected to machines and under observation differs from sleeping in normal bed. This task therefore lacks mundane realism. The study also had low ecological validity as the environment was artificial to the participants which could have made their sleeping behavior less typical. There was an ethical issue of deception as participant WD was told that he would be woken up in REM sleep but was actually woken up either in REM or nREM sleep randomly. This could have caused psychological distress as he could not give informed consent. Hassett et al. (Monkey toy preferences)
