CANLI et al study (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

• 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,

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.

Strengths:

- The experiment was conducted in a laboratory, as all the participants were tested via fMRI
machines and thus it was highly standardized.

- The research has high internal validity, as all variables such as time intervals for example,
were operationalized.

- This controls the influence to confounding variables that may distort results.

- The use of a scientific apparatus such as an fMRI machine produced highly objective,
quantitative data which is high in validity.

- This enables a comprehensive statistical analysis to be conducted which leads to better

- No demand characteristics were projected off participants.

Weakness:

- The task has low ecological validity due to the fact that it was conducted in a laboratory
environment.

- We also need to take into account the difference in levels of emotional intensity
experienced in a lab setting and that in the real world. Some participants may already be
emotionally aroused. And thus, the baseline itself maybe flawed.
- The researchers also need to be considering the fact that there are certain
biological, cerebral anomalies that a mere fMRI scanner can never fully represent all
behaviours exhibited by different and specific parts of the brain.

- This was a gynocentric study (based on only female participants). This may make
it difficult to be representative and thus, generalized.