title.

May 11, 2005 11:49 AM

blacks and whites agree: black people are scary! Scientists measured the amygdala response in white and african-american subjects when shown expressionless white and black faces. Interestingly, when paired with the words "African American" the response didn't register.
posted by delmoi (20 comments total)

Also see here: Amygdala activation differs depending on social cognitive goals when perceiving other-race faces.

I must take issue, however, because the amygdala is not responsible for only fear. Saying that amygdala activation equtes to fear is reductive and misleading.

Also see countless posts about the IAT, implicit attitudes, etc. (Full disclosure: Psychology graduate student who just finished a paper on other-race face perception).
posted by trey at 11:56 AM on May 11, 2005

"Five out of eight African Americans..."

Yipes -- talk about a small sample size. There are almsot as many authors on the "study" fercrisakes. This kind of thing gets into Nature these days?
posted by Cassford at 1:00 PM on May 11, 2005

I've raised similar concerns in the past, Cassford, but many neuroscience studies utilize small sample sizes, partly in due to the time and expense involved in working with neuro-imaging equipment. I raised a similar concern in my cognitive neuroscience seminar last semester and was told that "If the effect is there consistently, the sample size is unimportant." I was unconvinced.
posted by trey at 1:04 PM on May 11, 2005

I didn't mean to say "raise similar concerns twice."
posted by trey at 1:05 PM on May 11, 2005

Man, if their sample size is really only eight and eleven, I would love to see how their statistical analysis concludes the result is significant.
posted by Anonymous at 1:08 PM on May 11, 2005

Well, let's consider the things that influence statistical power: sample size, alpha level, and effect size. If you have a big enough effect, you can obtain significant results with a small sample size.
posted by trey at 1:16 PM on May 11, 2005

dese bizzatchiz iz wack.
posted by quonsar at 1:30 PM on May 11, 2005

Here's a PubMed link for Dr. Lieberman and his team, and one for Lieberman in general*. Looks like he's done some interesting work over the years.


*(which probably includes more than one MD Lieberman)
posted by me3dia at 1:31 PM on May 11, 2005

trey:

do you (hell, does anybody reading) know how they measure the effect in neural imaging experiments? Do they put a value on the size and intensity of the activity, or do they just subjectively compare it to a baseline?
posted by iron chef morimoto at 1:38 PM on May 11, 2005

Iron Chef Morimoto: In the case of functional MRI, they first smooth & blur the brain image to fit it on top of a brain "map" that has specified coordinates for various brain regions -- since all brains are slightly different, you have to massage them a bit to get them to map onto something standard. Then they set certain tolerances (like setting an alpha of .05, kind of) for certain voxels (the word used to describe 3-D pixels). If the voxels in a certain area show levels of blood flow beyond pre-set tolerances, the area is considered to be active above baseline. They can then run statistical analyses to determine if the area is significantly active and not just due to random error during the presentation of a given stimulus.

This is grossly over simplified, but I am not an expert on brain imaging.
posted by trey at 1:45 PM on May 11, 2005

first of all, i thought the 5 out 8, 7 out of 11 figures were just statistics representing a larger group of participants...did i miss something?

but that aside, if these are the results of a large, legitimate study, it just goes to prove the power of culture and media to effect people at their core. i doubt native africans would have displayed this type of brain chemistry in the 1200s. probably quite the opposite.
posted by es_de_bah at 2:09 PM on May 11, 2005

es_de_bah, I considered that, but then I thought: why would you say 5 out of 8 (63 percent) and not just "63 percent" if the sample size were larger? And then I checked the actual study and supplemental notes, which stated:

The participants were twenty right-handed individuals (11 Caucasian-American and
9 African-American....

I didn't read closely enough to see why they threw out one of the African American's results (aka, I couldn't figure it out).
posted by Cassford at 2:49 PM on May 11, 2005

"amygdala response" ... there's a joke in there about natalie portman, i just know it.
posted by LilBucner at 2:54 PM on May 11, 2005

there's a joke in there about natalie portman

"She's in the attic!"
posted by tkchrist at 4:09 PM on May 11, 2005

That wasn't it.
posted by blag at 4:46 PM on May 11, 2005

Can this really mean they have equal fear from a black face?
Because, I'm wonder if it is possible for most people in a a race having similar fear levels between them?
Now which races do I use here to make my example of having a higher fear factor?
Basically, knowing your death would create a high fear level. We read about heroes that risk their lives or a person that is terminally ill, but face the situation and move on quickly. So it salso seems for pictures when a fear overcomes a person from seeing it.

I’ve worked many a Knott’s Halloween Haunt where people have said their race scare the easiest. I’m not trolling here, people like to be acknowledged and finding it funnier reading this post. boo!Now what was the scare here? race.
posted by thomcatspike at 4:49 PM on May 11, 2005

That's ridiculous that the sample size is so small. That so obviously means that the expeirment is quite meaningless.... I'd be curious to see if it can be replicated.
posted by josh at 5:07 PM on May 11, 2005

josh writes " That's ridiculous that the sample size is so small. That so obviously means that the expeirment is quite meaningless.... I'd be curious to see if it can be replicated."

As trey noted, it is possible to get a significant result from a small sample size, so it's not so obvious that this is meaningless.
However, if you think it is, why would you want to see if meaningless data can be replicated?
posted by me3dia at 7:11 PM on May 11, 2005

Currently, "The Boondocks" comic has its young protagonist forcing himself to watch African-Americans on TV, 'screaming, sweating and grimacing', and little else, which is making him ill.
posted by kablam at 9:20 AM on May 12, 2005

me3dia, the effect would have to be quite large to allow 8 people to be a relevant sampling of the 35.1 million people who self-identify as African American, wouldn't it?

Ah, I knew I should have taken statistics in college. It just seems counterintuitive that 8 people could represent all black folks.
posted by Cassford at 10:37 AM on May 12, 2005