The grocery store is seven blocks from my house and I know exactly how to get there. But when my wife started driving there she took a wrong turn. To be fair, it was not so much a wrong turn as a different turn. You see, we were still heading in the right direction. We covered the correct number of blocks east and south, we just covered them in the wrong order. Her route got us to the store without incident, but it felt astray to me.

This moment intrigued me. Why did it feel bad to go a different route, even if we were still heading in the right direction? An instant after I asked her where the hell she was going, I realized she probably knew what she was doing. After all, she had been to the store enough that she knew how to get there, too. But it was too late. The fight was on.

So what was going through my head in that instant that made me sure she must have been mistaken? Although this precise scenario remains unexplored, proxy situations from experiments help explain my mental jump to conclusions. Most likely, my anterior cingulate cortex, or ACC, became excited, and sent a signal to other parts of my brain that something was amiss. Action needed to be taken.

The ACC lies at the front of the brain, at the middle boundary of each hemisphere. A series of fMRI experiments show it becomes activated when you make an error. During the error awareness task, participants watched as a series of color names appeared on a screen. They were supposed to press a button if the color of the font was different than the name. If they saw the word “blue” in green font, they could press the button and earn points. There were two situations when they were not supposed to press the button: if the same color name appeared twice in a row (blue, blue), or if the color name matched the font color. “Green” in green font? Hold your horses.

If they pressed a button when they were supposed to refrain, they could still earn some points by acknowledging their error and pressing a second button. This was an aware error. Otherwise, it was an unaware error and they got no points.

fMRI studies over the past decade have shown that when someone makes an error, more blood flows to the ACC. This indicates that the ACC is consuming more energy, presumably because it is hard at work. Since ACC activation occurs when someone makes an error, researchers surmised that it might be the brain’s signal that you’ve made an error. It’s your red squiggly line beneath a misspelled word.

When my wife turned left where I usually went straight, my ACC likely fired a warning shot. This was unexpected.

Is ACC activation enough to explain the shock I felt that we were going an unusual route? A recent analysis by Catherine Orr and Robert Hester suggests not. Participants had more ACC activity when they were aware of an error than when they were unaware of it. But they also had higher activation in several other regions, including the insula and supplementary motor area.

If the ACC completely explained error awareness, Orr and Hester thought there should be a strong relationship between ACC activity and behavior related to error-awareness. For example, most people become more cautious after making an error, slowing their responses to ensure accuracy. But when Orr and Hester looked at reaction time after an error and ACC activity, they found no relationship. ACC activation wasn’t directly linked to post-error caution.    

None of the other regions with greater activation during aware errors had higher activity in proportion to slower response time following an error. Based on Orr and Hester’s analysis, it may be impossible to determine which region is directly responsible for error awareness without further studies.

When we went a different route to the store, I was certainly aware that we were going a different way. This awareness was most likely initiated by ACC activity.

The ACC serves a crucial function in alerting you that things are going awry. Whereas Google maps may send you into a lake without even warning you to hold your breath, the ACC shouts, “This is wrong!” This likely sets off a series of signals that brings the error to your awareness and helps you change course.

So the next time you’re in a car and you tell your wife she’s going the wrong way, you may be able to prevent a fight. Even if it turns out her way is totally valid and you should have trusted her judgment, you can say, “Hey, at least I’m making sure we don’t drive into a lake.”

Image credit: marshallsegal

Reference: Orr C, Hester R. Error-related anterior cingulate cortex activity and the prediction of conscious error awareness. Front Hum Neurosci. 2012;6:177. doi: 10.3389/fnhum.2012.00177. Epub 2012 Jun 19. PubMed PMID: 22723775

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