Left Brain, Right Brain, Red Brain, Blue Brain

[En español]

With the first presidential debate of 2016 quickly approaching, it’s a good time to consider whether your brain has already cast its vote. There is no shortage of articles that imply your political leanings are reflected in your brain’s structure and function (e.g. Is your brain liberal or conservative?Fox News, Experts say liberal and conservative brains are wired differently Huffington Post, Could neuroscience explain what Trump voters are thinking?ResearchGate). Understanding these differences is surely important for future political neuroconsultants who, as one press release speculates, may learn to exploit them in order “to make more effective, biologically targeted appeals to voters.” It’s reasonable to assume that, just like the rest of our thoughts and feelings on any topic, our political positions arise through complex neural processes. But could it really be that our politics are hardwired in the brain?

A crude summary of several studies suggests there are differences in key brain regions that show conservatives/Republicans* are rigid and driven by emotional responses whereas liberals/Democrats are more flexible and open to change. It’s awfully convenient how well this aligns with our stereotypes about these groups. Perhaps a little too convenient. Let’s break down some of the research and evaluate these claims.


What makes a brain red or blue?


Compared to conservatives, liberals reportedly have a larger anterior cingulate cortex (ACC) [1] and stronger ACC activity [2]. The ACC is involved in cognitive control—the processes that allow you the flexibility to adjust your behavior to meet your current goals. Activity in this region has been related to conflict monitoring (keeping track


The ambiguous “rat-man” picture [4]

of and avoiding potential conflicts in information processing), which may serve as one way to signal the need for an adjustment in order to perform a particular task [for a review, see 3]. To understand how your previous knowledge, expectations, or goals can influence your interpretation of conflicting information, consider the “rat-man” picture [4]. Whether you see this ambiguous image as a rat or a man will depend on whether you’ve just viewed other images of animals or faces. It has been argued that the differences in ACC structure and function indicate liberals are more sensitive to conflicting cues, perhaps making it easier for them to alter their “habitual response pattern,” which goes along with the notion that liberals are more tolerant of ambiguity and conservatives are more structured [2].



MRI showing the location of the (a) anterior cingulate cortex (ACC) (b) the amygdala, and the insula [5]


Conservatives have been found to be both particularly attentive to and have stronger physiological reactions to aversive stimuli (e.g., an image of a spider on a man’s face) [6] and are more likely to read ambiguous facial expressions as threatening [7]. Further, people who have a greater physiological response to both sudden noises and threatening images are more likely to support defense spending and other policy positions concerned with protection from presumed threat [8]. These strong physiological responses may be attributable to brain differences. Conservative leanings and republican party affiliation have been associated with a larger amygdala [2] that is more active in response to risk-taking [9]. The amygdalaknown for its role in emotional reactionsis thought to be critical for fear conditioning, suggesting that conservatives have brains that are more responsive to fear.

Being easily disgusted has also been associated with conservative views [for more, watch this TED Talk]. You can even take a short test that, based on your response to questions like “Even if I was hungry, I would not drink a bowl of my favorite soup if it had been stirred by a used but thoroughly washed flyswatter” will tell you how liberal or conservative your brain is. Disgust is one of the universally expressed emotions and may be a very good reaction to have in order to avoid getting sick from eating rotten food. However, some suggest that this evolutionary function has been co-opted such that people who are especially disgusted by unclean images have political leanings that oppose things they consider to be morally impure (e.g., gay marriage) [10]. Conservative views have been linked to a larger insula [2] which has been associated with feeling disgust [11]. One study even used brain activation while viewing disgusting images (e.g., a mutilated body) to predict liberal or conservative group membership [12].  

It is tempting to say that Republicans support Donald Trump because he plays into their predisposition to feel threatened and promises protection by banning all Muslims from entering the US and building a huge wall to keep out Mexican immigrants whom he repeatedly calls criminals, rapists, and killers. Surely emphasizing feelings over facts makes sense when appealing to a voter base whose brains have such strong emotional reactions. Newt Gingrich understands playing to feelings, arguing that “as a political candidate,” he’ll “go with” the average American who does not feel safe despite contradictory statistics. But, despite our tendency to find neuroscience-based explanations especially credible (for more, see this post on neuromarketing), these studies simply don’t provide enough evidence to make such assertions.


Extrapolating beyond the data


A recurring problem in the studies mentioned above is the use of self-identified Republicans/Democrats or conservatives/liberals, often without any assessment of their political knowledge or even stances on key issues. Beyond the limits of using brain activation to explain behavior, many of these studies seem to pick and choose which of many functions of a given region to attribute to its involvement. As cognitive neuroscientist Martha Farah notes, the brain is complex and “the scattered spots of activation in a brain image can be like tea leaves in the bottom of a cup — ambiguous and accommodating of a large number of possible interpretations” [13]. It’s worth considering what alternative interpretations might be made if the results were reversed.

One study, reported on in 2004 by the New York Times, had data to suggest that the brains of Democrats had stronger amygdala activity in response to violent images in campaign ads. Ignoring the problem of evaluating results from research that has not undergone peer review, the authors argued that this was “a plausible outcome that matches some of our stereotypes about liberal values: an aversion to human suffering, an unwillingness to rationalize capital punishment and military force, a fondness for candidates who like to feel our pain.” This demonstrates how easily results can be framed to fit a narrative. Researchers also fail to point out findings that are seemingly incongruous when the overarching conclusion is consistent with their expectations. For example, increased activation in the insula was associated with liberals in the study that predicted group membership from activation in response to a disgusting image [12] despite research suggesting the link between conservative views and insula size explained conservative’s disgust sensitivity [2].

Unsurprisingly, studies like these have received a fair amount of criticism. In response to another piece published in the New York Times that suggested the authors could glean insight into the 2008 presidential election based on the brain activity of 20 self-described swing-voters, an editorial in the scientific journal Nature warned of the dangers of making sweeping claims based on brain activity in a given region. “That insula activity did not necessarily mean the subjects were disgusted. Insula activity has also been associated with drug craving, the taste of chocolate, pain and the quality of orgasm. Not necessarily such bad news after all” [14]. Further, it is all too easy to fall into the trap of confounding correlation and causation. Even if all of the described differences were real, there is no evidence to suggest that having an active ACC makes you liberal any more than your experience as a liberal affects the activity of your ACC.


What do we know about your brain in the voting booth?


If we can’t rely on these studies, what do we know about how we choose a candidate? You may have heard that things like facial appearance [15], height [16], and even voice pitch [17] all influence the way we vote. brainballotIn a study comparing simulated voting behavior in patients with damage to the lateral orbitofrontal cortex (OFC) to healthy individuals and those with other frontal damage, researchers found that damage to the OFC led subjects to use only information about attractiveness to make their choice, rather than incorporating information about competence [18]. This suggests that the OFC may play a role in bringing together multiple sources of information to make a decision. Despite this, our brain uses shortcuts all the time to make decisions easier, and we develop unconscious biases. This may lead you to wonder, as one CNN segment did, “Could it be that your unconscious brain actually chooses political candidates for you?” Implicit biases are certainly real (you can test your own biases in a range of areas here), but do we necessarily act on them? In a 2007 study, researchers found that despite a majority of subjects saying they would vote for Obama, their performance on an implicit association test suggested they preferred Clinton – and we know how that turned out. While it is important to recognize these implicit biases, they may not be the best predictor of our actions—sorry budding neuromarketers!

As the debate nears, it’s worth noting that another type of bias is alive and well in politics. Confirmation bias is our tendency to look for and interpret evidence to support what we already believe. In one study, when partisan subjects were presented with information that went against their candidate, researchers observed greater activity in several brain regions involved in emotional processing, but noted the dorsolateral prefrontal cortex—typically associated with logic and reasoning—was not particularly engaged in this task [19]. Unless you are one of the often-mocked undecided voters, chances are you are going into this debate with a few strong opinions. It may be wise to be a bit more skeptical, especially when something seems to fall exactly in line with what you already believe, and be critical of any grandiose claims—like that something as complex as political ideology can be readily revealed with just a peek at your brain.  



*An important caveat for interpreting this research: most of it took place in the United States and focuses on differences between the brains of people who a) are members of the Republican or Democratic parties or b) classify themselves as conservative or liberal.


Title image adapted from DonkeyHotey and pixabay



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