The Pretty, Compelling Pictures of fMRI

They say a picture is worth a thousand words. And there’s a good reason we humans find an image so compelling — most of the information we gather about the world around is done visually, through our eyes.

For instance, when you’re chatting with your best friend over coffee, up to 80% of that communication is done through nonverbal means — the way you smile when she says something funny, a gesture of your hands to emphasize your point. For better or worse, people are visually-oriented organisms.

So it’s no wonder that humans love research that comes with pretty pictures. And not just pretty pictures, but compelling pretty pictures that seem to illustrate a direct, causative relationship. Even if one doesn’t exist. Or other data exist that water down the pretty-picture study’s findings.

The problem is an age-old one and simple — a lot of psychological research is dry, boring stuff. You don’t have to look very far to see how boring it is. The American Psychological Association’s monthly journal is so boring, they rotate the artwork on its cover to try and imbue some excitement into its contents (as do many academic journals). Beyond the boring tables of data and occasional graph, the only other graphic in a typical issue is a smiling picture of the study’s authors. It’s no wonder much of this stuff never makes it to mainstream news stories.

Enter a possible solution — measuring stuff, or more specifically, “brain stuff.”

Of course researchers have been measuring brain stuff for decades via EEG, EDR, response times, and numerous other objective, data-based methods. Many of these even produce potentially-colorful graphs with little spikes that could almost be seen as interesting by a few psychologists.

But whoa, what’s this cool-looking picture of our brains at work? MRI?? No, not just an MRI, but a functional MRI! That means they are taking pictures of your brain while you do stuff.

The Basics of an fMRI

What does an fMRI actually measure? The fMRI indirectly measures the flow of oxygenated blood in the brain. That’s all. Not “activity of the brain” as it is often referred to in short-hand by journalists (and even some researchers). How is a typical fMRI study conducted?

Experiments using fMRI take about 1 to 2 hours per participant and each scan costs approximately $1500. Subjects lie down on a narrow plank, within a tube, and remain as still as possible. Even a millimeter of movement can ruin the data.
— Christie Nicholson

Researchers then correlate the flow of this oxygenated blood to some activity the person performs (yes, usually within the narrow confines of that tube!). Notice that annoying little “correlate” word in there too. Yes, correlate. None of these studies can show a causative link between a thought or behavior and a specific brain region.

The most well known shortcoming of fMRI is its slow timing. The blood flow response takes about two seconds, but a thought can happen in milliseconds. So it’s difficult to say that a rush of blood is associated with a specific activity in the brain.

[…]
Unfortunately a timing issue comes up again when researchers attempt to study communication between [brain] regions [trying to study more complex or abstract constructs]. This high frequency connection can happen within a hundredth of a millisecond and blood flow is far too sluggish to mark it.
— Christie Nicholson

So there are some challenges in getting the pretty pictures to line up with actual behaviors or thoughts (or political preferences, as at least one researcher has attempted to show).

As any brain researcher will acknowledge, too, brain activity happens at the neuronal level (according to our best theories), not by blood flow. It’s akin to trying to understand the process of photosynthesis in plants by measuring how much sunlight a tree or plant is getting. You’ll see the tree grow or plant shrink based upon sunlight, but you’re still not really much closer to understanding the process of photosynthesis. And you may be missing other important, parallel processes you’re not even measuring (such as temperature, in our photosynthesis example).

So do these pictures tell us some piece of new information that other studies haven’t told us? Well, in many cases, no. In research where there’s a claim that one specific area of the brain is the answer to, well, any one thing — love, fear, anger, depression, you name it — the researchers are usually over-reaching, over-generalizing and just trying to get more press and more research grants. These studies are pop-psychology often at its worse, no better than measuring the bumps on our heads to tell us what’s wrong with us.

In these “lazy” fMRI studies, the press reports on the results as though something important has been discovered. But more often than not, it’s nothing more than a few new pretty pictures of someone’s brain doing something.

How Can We Be So Naive?

How can journalists, research grant review committees, editors, peer-reviewers, and everyone else just get so taken in by these studies?

It all goes back to the pretty, compelling pictures.

An action photo, as any photojournalist can tell you, is far more interesting than a shot of a static, unchanging subject. We’re more drawn to photos showing something happening. And while research data is often showing something interesting happening, it’s primary downfall is that it’s data, not a photo.

Data: boring. Photo: interesting.

Photo of our brains in action: really interesting.

Some researchers are getting it right, however, such as Adam Gazzaley’s research center at the University of California, San Francisco’s Mission Bay campus. This article describes his research in Wired magazine. Researchers have started embracing these new, more complex techniques for brain analysis, which will hopefully lead to more robust and generalizable conclusions.

The future of the usefulness of brain fMRIs is by conducting more careful, nuanced experiments that move away from the simple, “Think of X; Oh look, this is where X lives in the brain!” It is now understood that our brains are more complex than a simple blood flow analysis can demonstrate. So that while these pretty pictures of our brains remain, hopefully more emphasis will be given to the complexity of human behavior and what the prior ten decades of psychological research has found (even though it didn’t come with the pretty pictures).

Further Reading

I’m not the first to write a critique about the pretty, compelling pictures of our brains in action. For another take on this issue, I suggest Paul Bloom’s 2006 article in Seed magazine on the same topic. Bloom made the following insightful observation in that article:

The mind is what the brain does, and so every mental event, from falling in love to worrying about your taxes, is going to show up as a brain event. In fact, if anyone were to find an aspect of thought that did not correspond to a brain event, it would be the discovery of the century, as it would be the first ever proof of hardcore Cartesian dualism.

If you’re really interested in learning about all of the possible issues that come into play with fMRIs, I highly recommend fMRI for Newbies, especially the page, How to Lie with fMRI Statistics. It’s a very thorough look at all the challenges that face modern fMRI researchers.

Christie Nicholson’s article on fMRIs, Reading the brain, presents a nice, balanced explanation and description of the pros and cons of fMRI research today, and where it’s likely to go. Using a comprehensive battery of brain measuring tests (EEG with fMRI) seems to be the next big step in brain research, along with advanced statistical techniques.