Review: Canli (Brain Scans and Emotion)
Psychology Being Investigated /- The study wanted to examine the link between amygdala activation in the brain and long-term emotional memories.
- Researchers wanted to show that event-related functional Magnetic Resonance Imagery (fMRI) scanning techniques can help us to understand emotional behavior.
AIM / Cambridge
- Canli et al. aimed to show that emotive images will be remembered better than those that have little emotional impact on an individual
- The central question addressed by this study were whether the amygdala is sensitive to varying degrees of emotional intensity to external stimuli and whether the level of intensity enhances memory for the stimuli.
- To investigate whether an area of the brain called the “amygdala” is sensitive to different levels of intensity to emotions based on subjective emotional experiences
- To investigate whether the degree of emotional intensity affects the role of the amygdala in aiding memory recall of stimuli classed as being “emotional.”
Hypothesis / N/A
Research Method/ Design / Lab Experiment
Variables:
IV & DV / IV- Intensity of emotional arousal to each of the 96 scenes presented to each participant.
•Had to choose from 4 buttons to indicate emotional arousal on a scale of:
Zero (0) Not emotionally intense at all to
Three (3) Extremely emotionally intense
DV:
- Level of activation of the amygdala measured by fMRI during the 1st stage of the experiment when participants were exposed to each of the 96scenes. During functional scanning, 11frames were captured per trial. Therefore, for each of the 96 scenes, there were 11 fMRI measures of neural activity.
- Measure of memory when participants had to recognize the images 3 weeks afterthe initial experiment
Sampling Method / Volunteer
Sample / •Ten (10) Right Handed healthy female volunteers were scanned (recruited).
•Chosen because it was thought that they are more likely to report intense emotional experiences and show more physiological reactions to the stimuli than men
Procedure / Materials:
•fMRI- GE Signa MR imager 1.5 Tesla fMRI scanner
•Projector with 96 scenes
•Emotional Arousal Scale
•Projector with 96 scenes and 48 foils
Scenes:
•Series of 96 scenes presented via overhead projector and mirror to participants during scanning to allow them to see it while in the fMRI scanner
–All 96 scenes were from “International Affective Picture System” stimuli set.
–Average ratings for valence (attractiveness or aversiveness of an event, object, or situation).
•Ranged from highly negative (1.17) to neutral (5.44) and from tranquil (1.97) to highly arousing (7.63)
–Order of scenes randomized across participants. Each picture presented for a period of 2.88 sec.
–Interval of 12.96 sec where participants viewed a fixation cross
•fMRI data- Collected by the scanner pictured to your right. (Used to measure activity in the brain) and blood-oxygen level-dependent contrast.
•Contrast imaging is a method used in fMRI to observe different areas of the brain found to be active at any given time.
•During all scans Ps head movement was minimized via a bite bar.
•Structural Image- 8 slices were obtained for each participant
•Functional image- 11 frames were captured per trial per participants
Each frame was assigned either as a baseline image (frames 1,2,10, and 11) or an activation image (frames 5,6,7, and 8)
Procedure Stage 1:
•Participants instructed to view each picture for entire time displayed.
•After its replacement with a fixation cross, they were to indicate their emotional arousal by pressing a button with their right hand.
•Choose from 4 buttons to indicate emotional arousal on a scale from 0 (Zero) not emotionally intense at all to 3 (Three) extremely emotionally intense.
Stage 2:
•3 weeks after 1st stage- Ps were tested in an unexpected recognition test in a lab. Ps viewed 96 previous scenes and 48 new scenes (foils)
–Foils- Selected to match previously presented scenes in their valence and arousal characteristics.
•Ps asked if they had seen the scene before
–If yes- they were asked whether they remember the scene with certainty (remembered) or has less certain feeling of familiarity (familiar)
–# of forgotten scenes was also records
Data Collection / Strengths:
•Use of an fMRI scanner to measure one of the DVs provided the researchers with vast amounts of quantitative data relating to the activation of the amygdala, enabling them to carry out statistical analyses such as correlational analysis about the level of activation and subsequent memory of the scene.
•Using fMRI scanners to measure the biological response on the brain of the different images gives an objective finding for each participant as it does not need the research to interpret any results.
•Although the task of being scanned in an fMRI scanner is hardly ecologically valid, it would not be possible for the participants to respond to demand characteristics, which increases the validity of the data collected and allows for sophisticated analysis.
Quantitative data- Canli collected a large amount of quantitative data. This has the advantage that statistical analyses to look for trends and differences are easy to conduct
Weakness:
•We need to be careful that we do not infer too much from fMRI results as there are still many unknowns about locations of specific behaviors in the brain.
•There is insufficient knowledge of the physiological basis of the fMRI signal to interpret the data confidently with respect to neural activity and how this maps onto specific behaviors.
•Although most fMRI research uses contrast imaging as a method to determine which parts of the brain are most active, because the signals are relative to individuals rather than measuring against a baseline, some question the validity in comparisons across individuals.
- BUT…..the use of a RMD strengthened this by minimizing the impact of this as participants’ scores were compared against themselves. (making this part a strength).
•Correlational aspects of the study- Analyses used correlational mapping which only shows that there was a relationship between the valence of pictures and the brain activation in the amygdala. Therefore, the cause and effect argument above may not apply.
Results /
- Participants’ experience of emotional intensity in the present study correlated well with average ratings of emotional valence and arousal.
–Ps ratings of emotional intensity reflected equally well the valence and arousal characteristics of the stimuli.
–Ps ratings of emotional intensity were equally distributed
•0=29%, 1=22%, 2=24%, 3=25%
•Amygdala activation was significantly correlated with higher ratings of experienced emotional intensity
•Amygdala activations is related to the subjective sense of emotional intensity and that the participants’ perceived arousal is associated with amygdala activation.
–Follow-up memory task- Indicated that memory performance was significantly improved for scenes that were rated as highly emotionally intense (3) than for scenes rated less emotionally intense (0-2)
–Scenes rated 0-2 had similar distributions of % forgotten, familiar, or remembered,.However those rated a 3 were remembered and were familiar with a higher frequency than those rated 1-2.
•Scenes rated highly emotional, the degree of left (but not right) amygdala activation predicted whether individual stimuli would be forgotten, appear familiar, or be remembered in a later memory test.
–Little amygdala activation when viewing a picture rated as highly emotionally intense was associated with the participant’s forgetting the stimulus.
–Intermediate and high amygdala activations were associated with a participant’s later report of familiarity or confident recognition.
Conclusion / •The amygdala is sensitive to individually experienced emotional intensity of visual scenes
•The activity in the left amygdala during encoding can predict subsequent memory
•The degree to which the amygdala activation at encoding can predict subsequent memory is a function of emotional intensity
•The more emotionally intense an image is, the more likely it will be remembered
•Evidence is provided here to explain why people remember emotionally intense experiences well.
•Exposure to an event causing this arousal, such as a car crash or witnessing a crime, memory trace will be more robust.
•Findings appear to suggest that the amygdala reflects moment to moment subjective experiences
•Other findings were that the amygdala is sensitive to individual’ experienced emotional intensity of visual stimuli with activity in the left amygdala during encoding being predictive of subsequent memory.
•Some of the Canli et al. findings are correlational, showing an association between the emotional impact on the participant and the subsequent memory for the item.
Evaluation: Generalizability /
- Volunteer Sample- Suffer from a lack of generalizability, researcher is unlikely to gain a wide variety of participants to allow generalization because this technique draws in one type of person
- Weakness- - Canli chose a specific sample of females for a particular reason. This means that the findings may ONLY be representative of females. The ways in which males and females process emotional information may be different, and therefore conclusions about the brain regions activated may only apply to females.
Evaluation: Reliability / •High level of standardization and can be replicated to test reliability:
–Standardised procedure- All Ps were tested in a standardized environment, the valence scores and the length of time each picture was viewed for and given same items to rate in each condition.
–Other researchers could easily replicate this study to test reliability
•High level of control, researchers can be more confident it is the IV directly affecting the DV
–High Control: all participants experienced the same conditions (the valence ratings and the unexpected recognition task) mean that for each part of the experiment, the researchers could be confident that is was the valence of the pictures seen that was causing activity in brain areas such as the amygdala.
Evaluation: Application to everyday life / Application to everyday life- Findings of this study may be useful for advertising agencies. If emotionally intense information is more likely to be recognized or recalled at a later date then advertisements that will appear on television or in magazines may be designed specifically to contain intense imagery.
Evaluation: Validity /
- Research has internal validity as the researcher can be more confident that there are fewer confounding variables affecting the variables that they are measuring.
- In lab experiments participants take part in tasks that are nothing like real-life ones, so the tasks lack mundane realism
- Environment in which participants were tested not comparable to everyday situation.
- Low Ecological Validity
- Use of fMRI scanners limits the realismthat can be introduced into a study as they are large machines and participants have to lie very still while the measurements are being taken
- Practice effects- participants get better at a task when they complete a similar one
- Fatigue Effect- the more tasks participants do the more tired they might become
- Boredom effect- repeating similar tasks can bore participant
Evaluation: Ethics / Strength
•Confidentiality- researchers did not release any specific information about Ps
•ALL participants gave informed consentto be involved in study. Aware of the nature of the experiment.
•Individuals operating fMRI scanner were fully trained and competent in safety arrangements that should be followed during a medical scan
Weakness
•(Protection) Ps were exposed to emotionally charged imagery which may have stressed some of them. There is no record of P’s then being exposed to “happier” imagery to alleviate any negative mental state they may have found themselves in.
Debates: Individual v. Situational / N/A
Debates: Nature v. Nurture / Some psychologists may argue that because the findings show that emotions are linked to brain function, the study supports a link to nature. However, as experiences were not taken into account in the study, it could still be nurture causing the results.
Debates: Use of Children / N/A
Debates: Use of Animals / N/A