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 resulted 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.

PROCEDURE:
Informed consent was collected from the participants and they were informed about the aim of the experiment.
While the participants laid 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 wforgottenotte, familiar or remembered

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.