Science Fail Monday: How a dead salmon taught us about statistics

Any scientist knows the importance of a good negative control. A negative control in an experiment is a group of samples or subjects in which no response is expected to an experimental treatment. The experimental group can then be compared to the control group. Such negative controls are gold standards in science and are supposed to provide confidence in experimental results. However, occasionally, a negative control gives unexpected and hilarious results worth of an Ig-Nobel Prize, the highest honor for scientists who publish the silliest research. Such was the case in an experiment involving fMRI, human emotions, and an Atlantic salmon.

https://commons.wikimedia.org/wiki/File:FMRI_scan_during_working_memory_tasks.jpg

An example of an fMRI scan in a human. The red spots have higher brain activity when subjects are performing a memory task.

fMRI stands for functional magnetic resonance imaging. If you’ve ever had a knee injury or a concussion, you have likely experienced a normal MRI scan, which uses radio waves and a magnet to take a structural picture of the organ of interest. The “functional” in fMRI means that researchers can use MRI images to measure brain activity and take a snapshot of changes over time. When a strong magnet is turned on over the brain, the hydrogen atoms in all of the water molecules in the blood point in the same direction, like a compass needle next to a refrigerator magnet. When the magnet is turned off, the hydrogen atoms relax back to their original positions, which releases a signal. This signal changes based on how much oxygen is in the blood, so the end result is a picture of the brain with information about which regions have more oxygenated blood. Regions needing more oxygen are generally assumed to be more active. Researchers can even have study participants perform a task during an fMRI scan, such as viewing particular images or listening to music, and use the fMRI data to determine which areas of the brain are active during the task. These types of studies can tell us a lot about which brain regions are involved in everything from social situations to processing fear.

In the Ig-Nobel Prize-worthy experiment, researchers wanted to use fMRI to determine which parts of the brain were active in response to seeing human faces displaying different emotions. However, they needed a negative control for their human subjects just to make sure that any brain activity they saw in response to the faces wasn’t just due to chance. The ideal candidate for such a negative control? A four-pound Atlantic salmon, purchased by one of the researchers at the local fish market.

https://commons.wikimedia.org/wiki/File:Salmo_salar-Atlantic_Salmon-Atlanterhavsparken_Norway_(cropped).JPG

The authors of the IgNobel prize study used an Atlantic salmon like this one as their negative control.

The researchers put the dead salmon in their fMRI scanner and, for the sake of science, asked it what emotions it thought the humans were displaying in pictures flashed up on the screen in the scanner. The authors do not comment on the salmon’s responses, but it can be assumed that the salmon was not a model experimental participant and did not comply with the study directions. Expecting to see nothing, the authors analyzed the fMRI signal in the salmon’s brain before and after the salmon “saw” the photos of the faces. Imagine the shock in the room when a few spots in the salmon’s itty-bitty brain lit up like a Christmas tree, suggesting that it was thinking about the faces it saw. Duh duh duuuuuhh….zombie salmon?

Obviously, the salmon was not alive, nor was it thinking about the emotional state of humans. Luckily for the field of fMRI, instead of publishing a paper telling everyone they should use dead salmon to study human response to the emotions of others, the authors of this study delved deeper into why they were seeing “brain activity” in this very dead fish. In their original data, the researchers failed to correct for multiple comparisons: basically, because you are comparing so many brain regions to so many other brain regions, you’re much more likely to find a spot with significant activity in fMRI purely by chance (for more info on multiple comparisons, click here). The authors applied the appropriate statistical corrections to their data, and voila, no more zombie salmon. And then, because scientists have a funny sense of humor, they wrote up and published these results as a lesson to all on the importance of having a good statistician.

Peer edited by Claire Gyorke.

Follow us on social media and never miss an article:

Opening Our Minds to “Outsiders”

Who I am today is a reflection of all the sacrifices my immigrant parents made to achieve the American Dream. In the late 1970s, my parents fled the Communist takeover of Vietnam, leaving behind family and friends and spending weeks traveling by boat to come to the U.S. for a better future.

https://commons.wikimedia.org/wiki/File:35_Vietnamese_boat_people_2.JPEG

Vietnamese refugees traveling via boat.

Having arrived with little money and limited English fluency, my father worked long hours at a blue-collar job while my mother stayed home to take care of my younger sister and me. My parents always found ways to provide for my sister and me with what little resources they had, using their own hardships to inspire us to achieve more than they could have. I could not be prouder to be the daughter of “boat people,” refugees, and immigrants, a sentiment I hope the refugees and immigrants being turned away at our borders today due to the targeted travel ban will eventually share.

It may be easy for me to empathize with these affected refugees and immigrants because our shared experiences categorize us as part of the same in-group. In social psychology, an in-group is a social group arbitrarily defined based on similarities among its members (e.g., citizenship). And if you’re not an in-group member, then you’re likely to be denigrated as an out-group member, simply for your dissimilarities. Importantly, while there are often no objective differences between in-groups and out-groups, classic social psychology experiments show that minimally defined groups, such as being on a meaningless “blue” or “yellow” team, are sufficient for eliciting out-group bias, even in children as young as 6 years old. This “Us vs. Them” mentality results in people being more likely to help in-groups and discriminate against helping out-groups. While helping in-groups may promote social connection, choosing not to help out-groups may cultivate feelings of rejection or exclusion, reinforcing group boundaries in society.

During a time when Americans’ attitudes and behaviors are especially rife with out-group prejudices, how can we encourage aid and support for those less similar to us?

A recent study by Dr. Grit Hein and colleagues used neuroimaging methods to probe whether out-group biases that emerge implicitly in the brain can be changed through experiencing more positive interactions with out-groups. The researchers used a learning intervention in adults to examine whether attitudes and empathy toward out-group members would change after receiving help from an out-group member (experimental condition) just as often as an in-group member (control condition). Because it is more unexpected to receive help from an out-group member relative to an in-group member, the researchers hypothesized that experiencing more of this unexpectedly positive outcome would increase positive associations with out-group members.

Indeed, Hein and colleagues found that experiencing unexpectedly positive out-group interactions led adults to develop more positive attitudes towards out-group members, which in turn increased empathy-related processing in the brain (i.e., greater neural activation in the anterior insula) to out-group members. Especially promising, increases in out-group empathy were achieved after only two positive learning experiences with out-group members!

Thus, while our perceptions of out-group members — like refugees and immigrants — are often biased and may lead to negative societal consequences (e.g., intergroup conflict), the results of this study highlight just how malleable these arbitrary intergroup distinctions can be. By increasing how often we interact with people less similar to us — whether those differences are by race, citizenship, or whatever arbitrary feature that we think divides us— we can learn to be more accepting of every person’s unique and important contribution to the fabric of our nation. After all, we are each united in our pursuit for the American Dream.

Peer edited by Alissa Brown and Christine Lee. 

Follow us on social media and never miss an article: