Canli et al Flashcards
Aim of the study
To investigate whether the amygdala is sensitive to different levels of experienced emotional intensities
To investigate whether the degree of emotional intensity affects the role of the amygdala in enhancing memory
Hypothesis
When amygdala is activated in response to emotional stimuli, memories of that emotional stimuli will tend to be stronger.
Sample
- Ten right-handed healthy female volunteers were scanned in a 1.5T magnet.
- Women were chosen in this study because they are more likely to report intense emotional experiences and show more physiological reactivity in concordance with valence judgments than men.
- Volunteer/self-selected sampling method
- Right handed women were chosen because activation in the left amygdala was being measured and also right handed people are a majority.
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 an experiment but correlational analysis was used.
Experimental design
This was a repeated measure design experiment as the participants were unexpectedly asked to repeat the procedure again three weeks after.
Procedure: (1) Exposure
Exposure:
1. Participants saw neutral and negative scenes
2. There were 96 images presented
3. They were presented through a mirror/projector;
each with a normative rating for valence and arousal, from the International Affective Picture System (IAPS) stimuli set.
4. For the scenes used in this study, normative ratings for valence ranged highly negative to neutral.
5. Normative ratings for arousal ranged from tranquil to highly arousing.
6. Arousal and valence (degree of negativity) were highly correlated.
7. Each picture was presented for a period of 2.88 sec (2-3s)
8. They had to view them the entire time;
9. There was a 12–13 s gap between each image,
10. The order of scenes was randomized across subjects,
11. Head movement was minimised via a bite-bar.
Data collection: (2) Emotional intensity
- They indicated how they experienced the emotional intensity of each scene.
- During the interstimulus interval of 12.96 sec, subjects viewed a fixation cross.
- Subjects were instructed to view each picture for the entire time that it was displayed, and after its replacement with a fixation cross they were
- They had to indicate their emotional arousal;
- By pressing a button (with their right hand);
- They had to choose from one of four buttons;
- From 0 (not emotionally intense at all) to 3 (extremely emotionally intense)
Data collection: (3) Brain Scans
- A separate fMRI response was recorded in the amygdala for each such emotional experience.
- Equipment used:
MRI / Magnetic Resonance Imaging/Imagery;
the purpose is to look at the structure of the brain
fMRI / functional Magnetic Resonance Imaging/Imagery - The purpose is to show the location of brain activity.
- 11 frames were captured per trial.
- Head movement was minimized by using a bite-bar formed with each subject’s dental impression.
Test: (4) Recognition Tests: Three weeks later, participants’ memories for the scenes were assessed.
- The participants were given an unexpected recognition test;
- They viewed all previous (96) seen scenes;
- They viewed 48/new/never seen before foils;
- The foils were chosen to match the previous scenes on valence/arousal;
- During the recognition test, participants were asked if they had seen the picture before;
- Forgotten, familiar, and remembered trials were encoded in a numerical format (as 1, 2, and 3, respectively) to construct correlation maps.
- No rating was asked for if they stated that they had not seen it before.
- Thus, each amygdala response could be related to the participants’ report of their experience of emotional intensity at study, and to long-term memory for that experience.
Results 1. Emotional intensity
- There was a negative correlation between emotional intensity and valence. The r value was –0.66
- There was a positive correlation between emotional intensity and arousal. The r value was +0.68.
Results 2. Amygdala activation:
- There was a positive correlation between emotional intensity and (left) amygdala activation.
- The red line charts the percentage activation of the amygdala which is far greater than the other lines,
- especially compared to the green line which represents the percentage of activation for emotional intensity rated 0 which was for not ‘emotionally intense at all’ responses.
Results 3. Memory recall
‘Remembered’ scenes
- The scenes which had higher emotional/intensity ratings were remembered more than those with a low emotional/intensity rating
- 42% of scenes rated 3 were ‘remembered’
- Those rated 0–2 had similar levels of % remembered. And were less than those rated 3;
Conclusion
- The activity in the (left) amygdala during encoding could predict subsequent memories (2 marks)
- Memory recall better for emotionally intense scenes
Level of left amygdala activation was a predictor of recall/subsequent memories
Strengths
- Sample: As they were volunteers there was no issue around giving informed consent.
- An fMRI scanner was the main piece of apparatus used. It is a highly reliable piece of scientific equipment which gives accurate and quantitative data.
- The environment was highly standardised ensuring that the conditions were the same for all.
- The carefully applied controls gave the study internal validity because there was a reduced chance of extraneous variables coming in.
Weaknesses
People may act differently when having a scan compared to real life so the emotional intensity scores may have been different in a real-life situation rather than on a screen. This might reduce the ecological validity of the study. (2 marks)
People may feel stressed/anxious whilst having a brain scan (1st mark) and this could have affected how they rated the emotional intensity of each picture/scene (reducing validity) (2nd mark);
Only left-handed people and women were used; this could arguably affect the generalisability of the results to left handed people and men.
