Could lessons in genetic variation help reduce racial prejudice?

Richard Dawkins called it "the curse of the discontinuous mind" - our tendency to lump things into discrete categories. Nowhere is this more apparent than in our perception of ethnic races, which we tend to see as reflecting absolute dividing lines in the human population. Do mistaken folk beliefs about genetics play a role in this? A new study by Jason Plaks and his team suggests so. What's more, their findings have interesting implications for an anti-prejudice intervention based around genetics lessons.

The background to this work is that people often mistakenly assume that superficial ethnic characteristics are a reliable sign of significant genetic difference. In fact, each of us is about 99.9 per cent similar genetically to the next person. And the genetic variability that does exist in the human race tends to be greater within ethnic groups than between them.

Plaks and his colleagues devised an ingenious memory test to expose the tendency of their 84 student participants to see black and white races as clear-cut categories (the students were from various ethnic backgrounds, but the majority were white). The stimuli were faces morphed from real photos of black and white people to consist of seven degrees of prototypical blackness and whiteness (including: all black, all white, 50/50, 16.67 per cent black, 16.67 per cent white, 33.33 per cent black and 33.3 per cent white).

These faces appeared in sequence on-screen interspersed with numbers. The participants' task for each number and each face was to say whether it was the same as the last seen number or face. For people who see ethnic races as distinct categories, the racial profile of the faces ought to have interfered with their memory performance. That's exactly what was found.

After the task, the participants were asked how much genetic overlap two random people on earth would be expected to have (the average answer was 56 per cent). Those participants who said there would be less overlap tended to be the same ones who were affected by the racial profile of the faces. That is, they were more likely to say mistakenly that the current face was the same as the last face, if the two faces had a similar racial profile. This suggests they were using racial cues to remember the faces. By contrast, participants who believed there is more genetic overlap between strangers tended to be unaffected by the racial profile of the faces. Presumably they used more idiosyncratic features of the faces to remember them by.

If belief in genetic variation is correlated with people's tendency to categorise faces according to race, then what if people are educated about human genetic variation - might that change their proclivity for prejudice? The next stage of the Plaks' study suggested so.

Half of 95 participants read a passage of text (adapted from a real American Psychologist article) that correctly stated the 99.9 per cent genetic overlap between random individuals, and drew an analogy between ethnic groups and social clubs. The other half of the participants read a version that said genetic overlap between individuals is low (21.4 per cent) and drew an analogy between ethnic groups and families. Again, the participants were from various ethnic backgrounds, but most were white.

Afterwards the participants had to rate words (e.g. "disgusting", "delightful") as either positive or negative as fast as they could. A crucial twist was that the words were preceded by a face prime with varying degrees of racial black or whiteness. For the participants who read the low genetic overlap text, the racial profile of the face prime made a difference - they were quicker to categorise negative words after a face that was 25 per cent black or more. By contrast, the racial profile of the face primes made no difference to the performance of the participants who read the text explaining the high genetic overlap between humans. In other words, being educated about the genetic overlap between humans seemed to reduce participants' sensitivity to, and discrete categorisation of, racial colour, thereby reducing their implicit prejudice in the word recognition task.

Plaks and his colleagues said this result suggests people's beliefs about genetic variation are malleable and could therefore be a useful target for anti-prejudice interventions. "People without a strong motivation for prejudice - and even those with professed egalitarian ideals - frequently display signs of racial stereotyping," the researchers concluded. "We suggest that people with egalitarian ideals may still exhibit stereotyping at least partly because they harbour particular assumptions about genetic variation."
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Plaks, J., Malahy, L., Sedlins, M., and Shoda, Y. (2011). Folk Beliefs About Human Genetic Variation Predict Discrete Versus Continuous Racial Categorization and Evaluative Bias. Social Psychological and Personality Science DOI: 10.1177/1948550611408118

This post was written by Christian Jarrett for the BPS Research Digest.

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Debunking people's belief in free will takes the intention out of their movements

Undermining a person's belief in free will alters the way their brain prepares for a voluntary movement. Davide Rigoni and his colleagues, who made the finding, aren't sure what the precise mechanism for this effect is, but they speculated that bursting the free will bubble somehow causes people to put less intentional effort into their movements.

Rigoni's team tested thirty participants on a version of Benjamin Libet's classic task from the 1980s. This requires that participants watch a dot proceed round a clock face, that they make a voluntary finger movement at a time of their choosing (the current study had participants press a button), and then make a mental note of the position of the clock at the time they made their decision to move. Libet's controversial discovery, replicated here, was that the brain begins preparing for the finger movement several hundred milliseconds prior to the conscious decision to move, as revealed by electrical activity recorded via electrodes on the scalp. The finding implies that free will is illusory.

For Rigoni's task, an additional detail was that half the participants read a passage debunking our sense of free will (see comments for the text) before they completed the Libet task. The other half acted as controls and read a passage about consciousness that didn't mention free will.

The new finding was that the earliest phase of preparatory brain activity known as "the readiness potential" differed between the two groups. This early component (around 1300 to 400 ms prior to the voluntary movement) was weaker in the brains of the participants who'd had their belief in free will diminished. Moreover, a questionnaire administered afterwards showed that this effect on brain activity was greater among the participants who reported having less belief in free will. In contrast, later phases of the brain's preparatory brain activity were not correlated with belief in free will.

What do we know about the early phase of preparatory brain activity that was affected? Quoting Lang (2003), Rigoni and his colleagues said that this early phase is associated specifically with movements that are executed with the "introspective feelings of the willful realisation of the intention to move at a particular time." In English, this means the early phase of preparatory brain activity is associated with just the kind of movement under study - a deliberate movement initiated at a consciously chosen time. The implication is that undermining someone's sense of free will leads them to invest less intention into an intentional movement. Exactly how one does that, and what it means, remains unclear. Rigoni's team conceded in their conclusion: "How disbelief in free will affects intentional effort is an open question."

They added: "In sum, our results indicate that beliefs about free will can change brain processes related to a very basic motor level, and this suggests that abstract belief systems might have a much more fundamental effect than most people would expect."

The study builds on past research showing how undermining people's belief in free will affects their social behaviour, for example encouraging them to cheat.
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Rigoni, D., Kuhn, S., Sartori, G., and Brass, M. (2011). Inducing Disbelief in Free Will Alters Brain Correlates of Preconscious Motor Preparation: The Brain Minds Whether We Believe in Free Will or Not. Psychological Science, 22 (5), 613-618 DOI: 10.1177/0956797611405680

Previous Digest reports featuring Libet's classic task: Libet Redux: Free will takes another hammering and Exposing some holes in Libet's classic free will study.

This post was written by Christian Jarrett for the BPS Research Digest.

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