Most sheeple in the United States say they accept interracial relationships, but studies of brain activity shows some hidden bias.
Researchers found that the insular cortex, a part of the brain that registers disgust, was highly active when participants viewed the photos of the interracial couples, but was not highly engaged when viewers saw the images of same-race couples, whether they were white or black.
Researchers surveyed students at the University of Nebraska — young people, not those who grew up in a more conservative time — and recorded their brain activity while they looked at pictures of hundreds of couples.
In a survey of attitudes about relationships, the students reported little disapproval of interracial couples. But photos of interracial couples triggered activity in a part of the brain that registers disgust.
“It shows that people show a level of disgust compared to the [national] polls saying that everything is fine,” said Allison Skinner, lead author and postdoctoral researcher at the University of Washington.
In first study it was investigated the correlation between self-reported acceptance of interracial romance and self-reported disgust associated with interracial romance. 152 students were asked whether they accepted mixed-race relationships. The respondents were about evenly split between the sexes; 87 percent were white, 5 percent were Latino, 3 percent were Asian, 3 percent black and 2 percent were of some other race.
Second study was designed to determine whether interracial couples elicit a disgust response. Consistent with evidence that those who violate purity norms are perceived as disgusting was predicted that interracial couples would elicit a heightened disgust response among observers. Although evidence from polls indicating that (due to political correctness), declared bias against interracial relationships is low, researchers anticipated that a neural response measure would reveal substantially higher rates of bias.
Considerable evidence indicates that the insular cortex is preferentially active when participants experience disgust, thus, insula activation was particularly well-suited to serve as an index of disgust response to different types of couples. Specifically, they tested whether viewing images of interracial couples would produce neural evidence of disgust. To do so, participants had their brain activity monitored by electroencephalogram (EEG). They were shown 200 real engagement and wedding photos: 50 black men with white women, 50 white men with black women and 50 each of same-race black and white couples.
While sitting in front of a computer, the photos of mixed-race and same-race couples were randomly shown to participants. They were told that they had to quickly respond to whether the couple should be “included” or “excluded” from a future study on relationships by pressing a button that corresponded to each answer.
The results of Studies 1 and 2 provided evidence that bias against miscegenation is not only correlated with feelings of disgust, but that viewing images of interracial couples evokes disgust at a neural level.
In the third study 3, researcher investigated whether heightened state disgust leads to dehumanization of interracial couples.
Findings indicate that interracial couples are implicitly dehumanized relative to both Black and White same-race couples. In other words, participants were quicker to associate interracial couples with nonhuman animals and same-race couples with humans, in contrast to associating interracial couples with humans and same-race couples with nonhuman animals. Moreover, given evidence that disgust leads to dehumanization (e.g., Sherman & Haidt, 2011), was also included an experimental disgust induction. Researcher hypothesized that implicit dehumanization would be particularly strong among participants who experienced the disgust induction. As predicted, those in the disgust induction condition showed even greater dehumanization of interracial couples – consistent with the conceptual link between disgust and dehumanization.
Overall, the current findings provide evidence that interracial couples elicit disgust and are dehumanized relative to same-race couples. Findings also highlight the role of meaningful social units (e.g., couples) in person perception, an important consideration for psychologists conducting social cognition research.
Disgust acts as a motivational force to distance oneself from people, places, or things . In this way, disgust serves an important evolutionary function, by motivating people to avoid contamination with potential pathogens. Thus, when social targets are associated with disgust it can result in them being perceived as unclean, animal-like, or even subhuman.
Previous research shows that disgusting targets tend to elicit the most extreme kind of prejudice, known as dehumanization .
This kind of prejudice involves denying people of their full humanity, often treating them as nonhuman animals or even objects . For example, Harris and Fiske  found that people neglect to consider the thoughts and feelings of disgust-evoking targets.
Other research has shown that participants show a marked lack of neural activity in social processing areas of the brain (e.g., the medial prefrontal cortex) when viewing extreme disgust-eliciting targets (e.g., homeless people and drug addicts; ). Thus, if interracial couples elicit disgust dehumanization could be a result.
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L.T. Harris, S.T. Fiske Dehumanizing the lowest of the low: Neuroimaging responses to extreme out-groupsPsychological Science, 17 (2006), pp. 847-853, 10.1111/j.1467-9280.2006.01793.x
N. Haslam Dehumanization: An integrative reviewPersonality and Social Psychology Review, 10 (3) (2006), pp. 252-264,10.1207/s15327957pspr1003_4
L.T. Harris, Fiske Dehumanized perception: A psychological means to facilitate atrocities, torture, and genocide?Zeitschrift für Psychologie/Journal of Psychology, 219 (3) (2011), pp.175-181, 10.1027/2151-2604/a000065.Dehumanized