That’s it! I’m never reading another imaging paper again, ever. OK, I might read one or two, and I might even post about them, but for now I’m telling myself, for my own sanity, that I’m never, ever, under any circumstances, going to read another imaging study. If you read my last post, or have been hanging around here for a while, you may have realized that I’m not a big fan of cognitive neuroscience. More often than not (I’d argue, always), you can learn the same thing and more by doing behavioral studies, and in most cases it’ll cost you several hundred dollars less per participant. For example, I recently saw a talk by a famous memory researcher, who’s written a couple popular books on memory and its infelicities. In the talk, he presented research supporting an interesting hypothesis about the relationship between memory and thinking about the future. He had really interesting behavioral and neuropsychological data that, as far as I’m concerned, provided ample support for his hypothesis. But for whatever reason (perhaps because these days some people need to see imaging data to be convinced?), the bulk of his talk was on imaging studies that, aside from being poorly controlled (how do you control for all the aspects of thinking about the past and the future in an imaging study? I mean, really!), didn’t tell us anything he hadn’t already told us with his behavioral and neuropsychological data. Ugh.
But a paper in the February issue of Psychological Science really takes the cake. The paper, by Krendl et al.(1), is titled “The Negative Consequences of Threat: A Functional Magnetic Resonance Imaging Investigation of the Neural Mechanisms Underlying Women’s Underperformance in Math,” and as the title suggests, uses fMRI to investigate where in the brain stereotype threat occurs, at least when women are doing math. In case you don’t know, stereotype threat is the term used to describe the detrimental effects that awareness of negative stereotypes can have on performance. So, for example, when African American students are aware of stereotypes that associate black students and poor academic performance, they tend to perform worse academically, and when women are made aware of stereotypes suggesting that they’re not as good at math as men, they tend to do worse in math.
There is a ton, a ton of behavioral data now demonstrating that stereotype threat is real and can have a significant impact on performance. I’ve discussed that evidence at length before (here and here, for example), so I won’t go into it again in this post. I’ll just note that, despite the many demonstrations of the existence of stereotype threat, we still don’t have a real good explanation for why it occurs. That is, we don’t know the mechanisms underlying the effect. Some recent evidence points to the important role of verbal working memory. Specifically, math problems that create heavy working memory loads are more effected by threat manipulations than problems that are less working memory intensive(2). Regulatory fit may also play a role, perhaps by affecting working memory, but who knows(3)? At this point, though, any study that sheds light on the causes of stereotype threat effects would be valuable.
What wouldn’t be valuable, though, would be an imaging study. Especially one like this. In Krendl et al.’s study, they induced threat in women by having them perform an Implicit Association Test (oh, brother!) that forced them to associate gender and math, and were told in the instructions that the experimenters were using this task because of the existence of gender-math stereotypes. So participants who took the gender-math IAT were in the “threat” condition, while another set of participants took an unrelated version of the IAT, and were thus in the “non-threat” condition. Next, the participants got into the fMRI machine, and took a math test that involved viewing equations (5 x 2 – 3 = 7), and indicating as fast as they could whether the equations were true or false. All the while, they were having pictures of their brain taken.
All that’s fine, I suppose, but the resulting data suffers from two serious problems. The first, and most important problem, is that they didn’t get the stereotype threat effect. Let me repeat that. They didn’t get the stereotype threat effect!!! OK, now if you’re going to an explain an effect, or at least argue that it occurs in certain regions of the brain, using imaging data, it would be a good idea to first get the effect. But no! Here’s a graph of their data (from Krendl et al.’s Figure 1, p. 171) :
This is the accuracy data, and the first thing to notice is that Krendl et al.’s participants sucked at this task. The highest mean accuracy in any condition was just over 20%. Who knows why this is, perhaps the task was really difficult, perhaps the five seconds they were given to respond wasn’t enough time, or perhaps they were anxious about being surrounded by a giant, super-powerful magnet, who’s to say? But that’s not really important. What’s important is that if you look at the two bars on the right, the bar on the far right is slightly lower than the one on the left. This indicates that participants in the threat condition performed slightly worse after the threat manipulation than they did before it. Unfortunately, however, this difference wasn’t quite statistically significant. In other words, the threat effect itself was not statistically significant! So, they’re basing their imaging data conclusions on a non-significant behavioral effect. Oops.
Now to the imaging data. Krendl et al. found that, relative to the non-threat participants, participants in the threat condition showed less activation the left inferior
prefrontal cortex, left inferior parietal cortex, and the bilateral angular gyrus, during the second test (i.e., the one after the threat-inducing manipulation). These areas, it turns out, are associated with doing math. So what they’ve found, in essence, is that people who do better on math problems (i.e., those in the non-treat condition) show more activity in math-related brain areas than those who don’t (in this case, those in the threat condition). That’s, well, not exactly ground-breaking. And it doesn’t tell us anything about stereotype threat. They did find greater activation for participants in the threat condition, relative to those in the non-threat condition, in the ventral anterior cingulate cortex. This area is associated with negative emotions. So, we know that when people are doing worse on a math test, they have more negative emotions. Again, we haven’t learned anything about threat.
So, to summarize, this study didn’t get a stereotype threat effect and only showed differences in brain activation associated with, well, the consequences of threat, rather than with the mechanisms by which threat produces them. In short, then, we’ve learned that stereotype threat happens in the brain, we’re just not sure where, or how, or when. I say again, ugh. I wonder how much time the imaging data for their 28 subjects cost, because the research was funded by the NSF, and therefore your tax dollars and mine. I’m never reading another imaging study again.
1Krendl A.C., Richeson J.A., Kelley W.M., &Heatherton T.F. (2008). The negative consequences of threat: A functional magnetic resonance imaging investigation of the neural mechanisms underlying women’s underperformance in math. Psychological Science, 19(2), 168-175.
2Beilock, S.L., Rydell, R.J., & McConnell, A.R. (2007). Stereotype threat and working memory: Mechanisms, alleviation, and spillover. Journal of Experimental Psychology: General, 136, 256-276.
3Grimm, L.R., Markman, A.B., Maddox, W.T., & Baldwin, G.C. (Under Review). Stereotype threat reinterpreted as regulatory mismatch. Journal of Personality and Social Psychology.