Dehumanizing the Lowest of the Low

Neuroimaging Responses to Extreme Out-GroupsArticle 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

Envy6 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.