Dehumanizing the Lowest of the Low Neuroimaging Responses

Report
By Stephanie Clogg
Summary:
 Introduction
 Method
 Results
 Discussion
 My opinion on the paper
Introduction
 Aim: 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)
 High vs. low levels of perceived warmth and competence
 4 stereotype dimensions (Pity, Pride, Disgust, Envy)
 SCM predicts extreme out-groups (low warmth/low competence) will
be dehumanized
Competence
Low
High
Pity (elderly, disabled)
High
Pride (middle-class, athletes)
Warmth
Low
Disgust (homeless, addicts)
Envy (rich people, money)
Hypothesis:
 HYPOTHESIS: Extreme out-groups (low warmth/ low
competence) may NOT significantly activate the mPFC
 No social cognition - not perceiving
these groups as fully human???
Dehumanization!
No significant mPFC
activation
Extreme out-group
(disgust stereotype dimension)
Method:
Participants:
 22 Princeton undergraduates
 Included 6 ethnic minorities
Scanning parameters:
 3T Siemens Allegra head-dedicated MR scanner
 Participant responded with manual response pads
 Functional echoplanar imaging (EPI) sequence used
 Participants were familiarized with a similar
task before entering scanner
 Series of 6 runs of 10 photos
Image of social group
depicting 1 of the 4
SCM categories
Example of procedure for
Study Group 1
Response
screen
Pity
Pride
Baseline fixation task
Second image in
series...
Disgust Envy
6 seconds
2 seconds
12 seconds
6 seconds
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 quadrant
 Subtracted 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 1
 Significant 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: Disgust
 No 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 theories
 Weaknesses:
 Low number of participants all from
similar backgrounds and ages
 Further research:
 Use more people from different age
groups, demographic and racial backgrounds.

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