by stephanie clogg
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Dehumanizing the Lowest of the Low Neuroimaging Responses to Extreme Out-Groups Article by Lasana T. Harris & Susan T. Fiske. By Stephanie Clogg. Summary:. Introduction Method Results Discussion My opinion on the paper. Introduction. - PowerPoint PPT PresentationTRANSCRIPT
Dehumanizing the Lowest of the Low Neuroimaging Responses to Extreme Out-Groups
Article by Lasana T. Harris & Susan T. Fiske
By Stephanie Clogg
Summary:Introduction MethodResultsDiscussionMy opinion on the paper
IntroductionAim: To investigate through neuroimaging
if extreme out-groups are perceived as less than human
Prejudice is not just a simple animosity!Out-group Infrahumanization Theory
Medial prefrontal cortex (mPFC): necessary for social cognition
Activated when thinking about a person or making social judgements
Stereotype Content Model (SCM)
Low High
High Pity (elderly, disabled) Pride (middle-class, athletes)
Low Disgust (homeless, addicts) Envy (rich people, money)Warmth
Competence
High vs. low levels of perceived warmth and competence4 stereotype dimensions (Pity, Pride, Disgust, Envy)SCM predicts extreme out-groups (low warmth/low competence) will
be dehumanized
Hypothesis:HYPOTHESIS: Extreme out-groups (low warmth/ low
competence) may NOT significantly activate the mPFCNo social cognition - not perceiving
these groups as fully human???
Extreme out-group(disgust stereotype dimension)
No significant mPFC activation
Dehumanization!
Method:Participants:
22 Princeton undergraduatesIncluded 6 ethnic minorities
Scanning parameters:3T Siemens Allegra head-dedicated MR scannerParticipant responded with manual response padsFunctional echoplanar imaging (EPI) sequence used Participants were familiarized with a similar
task before entering scannerSeries of 6 runs of 10 photos
Pity Pride
Disgust Envy
6 seconds
2 seconds
12 seconds
6 seconds
Example of procedure for Study Group 1
Image of social group depicting 1 of the 4 SCM categories
Response screen
Baseline fixation task
Second image in series...
Procedure: The details•STUDY GROUP 1 (n=10) •STUDY GROUP 2 (n=12)•Affective assessments of images of SOCIAL GROUPS
• Affective assessments of images of OBJECTS
•48 color images of 8 social groups • 8 images of objects
• Each image depicts 1 of the 4 stereotype dimensions• All images randomly sequenced for each run and run order was randomized
•Showed each image only once •8 images presented 3 times with 6 neutral filler photos each run
•Image shown for 6 seconds •Image shown for 4 seconds
•Response screen shown for 2 seconds •Response screen shown for 4 seconds
After response, black screen with green cross in the centre was shown for 12 seconds before the next image
•In fMRI scanner, asked to decide which SCM quadrant each image belonged to.
Results:Data analysis:
BOLD signal response recorded from each SCM quadrantSubtracted activation during exposure to image from
activation during black screen display (baseline task)Resulting contrast maps were averaged across participants
Study 1 participants evaluated predicted SCM quadrant of image well above chance (0.25)
Pride Envy Pity Disgust.70 .52 .83 .64
Brain regions involved: Study 1Significant mPFC activations was revealed for pride, pity,
and envy but NO significant mPFC activation for disgust Red circled areas indicate mPFC activation
R=Right
Brain regions involved: DisgustNo mPFC activation, supporting the hypothesis!Disgust images (in study) were associated with activation
in the right amygdala &left insula
Discussion and summary:Due to absence of mPFC activation in low-low social
groups, suggesting lack of social cognition, members of some social groups are dehumanized.
Low-low social groups also ellicit neural patterns of disgust (insula) and fear (amygdala) according to meta-analyses
The proof of neural mechanisms involved in dehumanization may help explain hate crimes
and genocide
My Opinion on this study:Strengths:
Using fMRI and EPI monitors activity in the whole brain, which allowed them to find activation in the left insula for disgust category. (This would not have been found if they were only looking at localized activation in the mPFC)
Provided neurological evidence for previous theoriesWeaknesses:
Low number of participants all from similar backgrounds and ages
Further research:Use more people from different age
groups, demographic and racial backgrounds.