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.