Biological approach
Canli et al. (2000)-
AIM:
To demonstrate that images causing high arousal levels will be remembered better than those
that are less emotive. To investigate whether the amygdala is sensitive to varying degrees of
emotional intensity to external stimuli and find what level of intensity affects the memory of
the stimuli.
• Is the amygdala sensitive to varying degrees of individually experienced emotional intensity?
• What degree of emotional intensity affects the role of the amygdala in enhancing memory of
emotional stimuli.
BACKGROUND:
There are two types of medical scans: structural – take detailed pictures of the brain structure;
functional – show the location of activity in the brain. The study used an fMRI machine
(functional magnetic resonance imaging) which detects changes in blood flow in the brain to
illustrate how the brain works during different tasks. The individual is placed in a scanner which
sends a magnetic field and affects the spinning of the hydrogen molecules in the brain and
enables the scan to create a detailed picture of the brain. The amygdala has been shown to
have an association with the processing of emotion and storing of memory.
LeBar & Phelps (1998) suggested that emotional arousal aids the process of memory
consolidation and therefore emotional experiences are memorized better.
Canli et al (1999) found strong amygdala activation to result in improved memorization for the
causing stimuli. He wanted to replicate his study with repeated measures design rather than
independent to make sure that the initial results were not due to chance.
RESEARCH METHOD:
Participants were required to lay in an fMRI scanner, which is a big and heavy apparatus,
therefore the study was conducted in a laboratory and was a laboratory experiment.
EXPERIMENTAL DESIGN:
This was a repeated measure design experiment as the participants were unexpectedly asked to
repeat the procedure again three weeks after.
VARIABLES:
The independent variable can be considered the level of arousal of each picture shown to the
participants.
The dependent variable was the effect that this arousal level had on the memory of each
picture which reflected on the ability of the participants to recognize the images at a 3 week
follow up.
SAMPLE:
Participants were recruited by means of volunteer sampling and consisted of 10 healthy, right-
handed women. Women were chosen specifically as it was believed that they would be more
likely to show physiological reaction to stimuli.
RESULTS:
There was an appropriate correlation between the subjective valance rating of the pictures and
the valence of the pictures, with correlational coefficients of -0.66 and 0.68. Additionally,
amygdala activation was also found to correlate with the emotional intensity reported by the
participants – the more emotionality intense the picture was, the higher the amygdala activity
of the participants while viewing it – perceived arousal is associated with amygdala activation.
At the follow-up, the emotionally intense pictures were remembered significantly better.
Pictures rated 0 to 2 had a homogenous distribution of forgotten, familiar or remembered
labels while pictures rated with 3 were more likely to be labeled as ‘remembered’. For pictures
rated a 3, the amygdala activation could almost always predict correctly the label the
participants would give it at follow up.
CONCLUSION:
There is an association with the perceived emotional intensity of stimuli and the memory of it –
the higher valance a picture has, the more likely it is to be remembered. High levels of arousal
can produce more vivid memories. The amygdala has been found sensitive to emotional
intensity, predominantly the left amygdala’s activity during information encoding being an
indicator for the formation of the memory.
PROCEDURE:
Informed consent was collected from the participants and they were informed about the aim of
the experiment.
While the participants lay in a 1.5 Tesla fMRI scanner, they were shown 96 pictures with various
valence ratings from the International Affective Picture System, projected over their head and
mirrored for convenient viewing. The picture order was randomized and each picture was
viewed for 2.88 seconds, with an interval of 12.96 seconds between two pictures in during
which a fixed crossed was projected. The participants had to view the pictures the entire time
they were projected and when the cross appeared, they had to rate the emotional arousal the
picture triggered in them by pressing one out of four buttons with their right hand; the buttons
ranged from 0 to 3 with 0 being ‘not emotionally intense at all’ and 3 ‘extremely emotionally
intense’.
While the participants were laying in the scanner, the fMRI machine collected information
about the activity in the brain during the picture viewing.
After 3 weeks, the participants were asked to return to the laboratory, where they had to
undergo an unexpected task. It consisted of them viewing the same 96 pictures plus 48
additional foils and asked to judge if the pictures were forgotten, familiar or remembered.
Dement and Kleitman (1957)-
AIM:
To find out more about dreaming, specifically, find answers to the following questions:
• Does dream recall differ between eye movement (REM) and quiescent (NREM) stages of
sleep? Meaning, will individuals remember their dreams differently in REM and NREM
• Is there a positive correlation between subjective estimates of dream duration and the length
of the REM period before waking? Meaning, would the real duration of the REM length coincide
with the individual’s assumption about its length
• Are eye movement patterns related to dream content? Meaning, is what we dream
influencing how our eyes move during sleep
BACKGROUND:
Aserinsky and Kleitman (1955) were first to use an EEG (a machine that detects the activity of
nerve muscles) to investigate sleeping and dreaming. They found that humans have several
sleep stages during the night, which alternate from REM (rapid eye movement) to NREM (non-
rapid eye movement). They reported that those participants woken up during the REM sleep
stage reported more vivid, visual dreams.
RESEARCH METHOD:
This was a laboratory experiment since participants had to sleep in a laboratory, away from
their usual environment, with electrodes from the EEG attached to them.
EXPERIMENTAL DESIGN:
The experiment had a repeated measures design since all participants underwent generally the
same procedure, however, to find answers for specific questions, there were sometimes slight
differences for some participants.
VARIABLES:
For question 1, involving the difference between REM and NREM, the independent variable was
whether participants were woken up in REM or NREM and the dependent variable was how
well they recalled their dream.
For question 2, involving the real and subjective estimate of the dream duration in REM, the
independent variable was whether participants were woken up after 15 or 5 mins in REM sleep.
The dependent variable was whether their subjective guess of the estimate duration was right.
SAMPLE:
Initially, 9 adults were recruited to participate in the study – 7 males and 2 females. However,
only 5 of those were studied in detail. The results from the other 4 were used to confirm the
reliability of the other 5.
RESULTS:
It was reported that dream stages last from 3 to 50 minutes with a mean duration of 20
minutes and they were typically longer in the night. There were bursts of around 2 to 100 rapid
eye movements.
No rapid eye movements were recorded at the beginning of the REM sleep.
Sleep cycles varied from 70 to 104 minutes, mean duration of 92 minutes.
Participants tended to return back to NREM when woken on NREM but usually when woken in
REM, did not dream until the next NREM stage.
• Results for question 1: 79% of participants woken up in REM produced dream recall and 93%
in the NREM didn’t. Absence of dreaming during REM was more common later in the night.
When woken in NREM, participants tended to describe rather feelings and no specific dream
content. Participants did not become more accurate over time – they didn’t learn the pattern of
their awakenings.
• Results for question 2: 88% of participants guessed the 5 minutes correctly and 78% the 15
minutes correctly. The dream duration and the number of words used to describe the dream
narrative were significantly positively correlated.
• Results for question 3: Periods of just vertical or just horizontal were not common. One dream
throughout which the participants had only vertical eye movement involved climbing up a
series of ladders and looking down as he climbed and in another, the dreamer was shooting at a
basketball at a net. An example of a horizontal eye movement dream was two people throwing
tomatoes at each other. In a little no eye movement dream, the participants dreamed of staring
at a distant object. In mixed eye movement dreams, participants reported looking at close
object or persons. The eye movements from the awake comparison participants were similar in
amplitude and pattern.
CONCLUSIONS:
Dreaming is reported in REM but not in NREM. Participants can judge the length of their dream
duration – dreams progress in ‘real time’. Eye movement patterns relate to dream content.
PROCEDURE:
Prior to the study, participants were instructed to abstain from drinking caffeinated beverages
and alcohol. They were expected to arrive at the laboratory just before their usual bedtime.
They had to sleep in a dark room with electrodes attached to their scalp and the wires gathered
in a ponytail. They were woken at various times during the night by a loud doorbell and had to
describe their dream in a tape recorder and go back to sleep. The reports were operationalised
as ‘dreams’ if the participants could actually recall its content and not just a feeling or
impression of it.
• For question 1, participants were woken either during their REM or NREM sleep stages, this
was decided using either a random number table, in groups of three, deceiving the participant
in which sleep stage they were woken up in or at experimenter’s choice. If necessary, after
recording their dream, the experimenter entered to ask further questions.
• For question 2, participants were woken during REM sleep, at either 5 or 15 minutes after
entering the stage. They had to guess the duration of their dream. The number of words used
to describe the dream narrative was also counted.
• For question 3, participants were woken after a particular eye-pattern movement was
recorded by the EEG for more than one minute. These included mainly vertical, mainly
horizontal, vertical and horizontal or little to no movement. The reports were compared to 20
others from woken participants instructed to watch distant and close activities.
Schachter and Singer (1962)-
AIM:
To test the Two Factor Theory of Emotions – emotional experience is a result of both the
physiological arousal and the cognitive interpretation of a situation.
BACKGROUND:
Cognition – acquiring and processing knowledge and understanding through experiences,
senses, and thought. Emotion – body’s response to a particular situation. Schachter and Singer
suggested that our cognition about situations influences how we perceive our emotions and
therefore to label our emotion we use both our interpretation of physiological arousal as well
as the cognition about what is happening around us.
RESEARCH METHOD:
The experiment was a laboratory one as it was conducted in a controlled environment.
EXPERIMENTAL DESIGN:
The experiment had an independent group design as each participant took part in one of the
seven groups: epinephrine informed euphoria/anger, epinephrine misinformed
euphoria/anger, epinephrine ignorant euphoria/anger, and placebo.
VARIABLES:
The independent variables were the information the participants received about the effects of
their epinephrine injection – either they were told to correct symptoms – informed, told the
incorrect symptoms – misinformed or were not told about any symptoms – ignorant. Another
independent variable was whether the participants were placed in a room with a stooge in an
angry or euphoric condition.
The dependent variable was the reaction the participants exerted to the actions of the stooge
which was recorded by observers through a one-way mirror, as well as the results from the self-
report on their mood that they had to complete at the end of the experiment.
SAMPLE:
There were 185 individuals participating in the study, who were taking a course of introductory
psychology at the University of Minnesota. They were given course credit for participation.
RESULTS:
All 185 participants agreed to the injection, however, 5 of them had no physiological response
and therefore their data was dismissed. Another 11 participants were too suspicious and their
data was discredited, resulting in 169 data samples being analyzed. Individuals who received
the adrenaline injections showed more sympathetic arousal and had higher scores on the
questions in the questionnaire about palpitations and tremor. Therefore, those in the
adrenaline condition were more physiologically aroused than the placebo condition. Self-
reports showed that in the euphoria condition, the misinformed participants felt the happiest –
they used the happy mood of the stooge to explain their physiological arousal. The informed
euphoria group felt the least happy. In the anger condition, those in the ignorant group were
the angriest – they were more susceptible to stooge’s mood since they had no explanation for
their arousal.
CONCLUSIONS:
The results support the Two Factor Theory of Emotions which assumes that the physiological
arousal which we experience in relation to different emotions is the same and we label these
emotions based on available cognitions. All three proposed hypothesis were arguably
supported and found that indeed if there is a lack of explanation for a state of arousal the
feelings will be labeled based on available cognitions.
HYPOTHESIS:
• If a person doesn’t have an explanation to their state of arousal, they will label their feelings
based on immediate cognition.
• If a person has an explanation for their state of arousal they won’t necessarily take into
account available cognitions to label their feelings.
• If a person experiences a previously encountered emotional situation, they only react or feel
emotional if they are physiologically aroused.
PROCEDURE:
Participants’ medical records were checked to ensure the injection they were about to receive
could not have caused health problems; they were administered by a trained doctor. After the
participants arrived at the laboratory, they were deceived and were told the experiment
investigates the effect of the vitamin Suproxin on vision; in fact, they were injected with either
adrenaline or saline solution in the placebo condition. Participants were then split into the
informed, misinformed and ignorant conditions and being told different information about the
symptoms of the injection. In the informed condition, they were told the correct symptoms –
hands will shake, the heart will pound and blood will rush to the face. The patients in the
misinformed condition were told incorrect symptoms – the body will itch, feeling of numbness,
slight headache. Those in the ignorant condition were told to expect no symptoms. They were
then introduced to the stooge, who they were told was another participant and asked to wait
10 minutes for the injection to absorb in the bloodstream; the experimenter left saying the
participants were free to use the props in the room. The stooge, unaware of the participant’s
condition started performing their standardized routine. In the euphoria condition, he was
playing with hula hoops and pencils threw paper and invited the participant to join. In the anger
condition, the stooge made upsetting comments as well as asked the participant personal
questions such as ‘How many times a week do you have sexual intercourse?’. When the routine
was over, the experimenter returned to the room and measured participant’s pulse and gave
them the final questionnaire which included 4 questions: ‘How irritated, angry or annoyed
would you say you feel at present?’ or ‘How happy would you say you feel at present?’ to which
participants had to choose the mark most fitting their state: 0 – not at all, 1 – a little, 2 – quite,
3 – very, 4 – extremely. They were then debriefed, promised secrecy to and asked for consent.
