The Emerging Neuroscience of Class Differences

"Empire State of Mind" by Julia Buntaine
“Empire State of Mind” by Julia Buntaine

Ever since the Occupy movement swept the globe in 2011, class has been in session. The ambient frustration with the economic and political consolidation of the 1 percent was injected with further analytical clout by Thomas Piketty’s Capital, driven home by a 2014 Princeton study that announced we’re living in an oligarchy, and most recently, featured as a central tenet of Bernie Sanders’ insurgent presidential campaign.

In the meantime, there’s also been a growing body of work in the social sciences examining how socioeconomic status is linked to how people think, feel, and behave. Much of this work has been purely behavioral, but the emerging trend across a multitude of studies (see references, below) is that lower socioeconomic status is correlated with greater empathic attunement to others, greater engagement during social activities, stronger physiological empathic responses, as well as greater self-reported empathy– with the implication, of course, that great socioeconomic status means less of all that.

This emerging literature on the psychology of class differences is undeniably provocative, yet its measures have been relatively indirect. So neuroscientist Michael Varnum and his colleagues Chris Blais and Gene Brewer at Arizona State University set out to develop a new line of work in hopes of tracing the neural underpinnings of class differences.

In the past two years, Varnum’s results have been starting to come in, and they are confirming– in eye-opening fashion– what the social sciences have been saying for over a decade now about class-based differences in empathic capacities and self-centeredness.

In a study recently published in the journal Social Neuroscience, Varnum measured the effects of socioeconomic status on a particular band of frequencies in the brain– the synchronous activity of a large swath of neurons– known as Mu-rhythms. Mu-rhythms are of particular interest to the issues at hand because their suppression is thought to be a hallmark of the activation of the mirror neuron system, a candidate for the neural basis of empathy. Mu-suppression is weaker in autistic minds, and it’s been shown to be stronger with direct perception/action exchanges, like watching oneself be mimicked. But to date, nobody has measured this system across a range of socioeconomic backgrounds and tried to explicitly correlate its activity with class differences.

Figure 1: MacArthur Scale of Subjective SES.
Figure 1: MacArthur Scale of Subjective SES.

So Varnum first had the participants in his study answer a series of questionnaires to get at their background and current class position, including the MacArthur Scale of Subjective Social and Economic Status, which asks people to rank themselves on their subjective status relative to other Americans by placing an “X” on a ladder with a series of ten rungs. Varnum then created a “composite socioeconomic (SES) score” which could be more clearly plotted against the neural data he would be collecting.

Using EEG measurements, Varnum’s group traced the Mu-rhythms while participants engaged in a series of basic motor exercises used widely to measure empathic responses: action observation (in this case, watching a hand opening and closing), action execution (doing the same, while watching their own hand), and a baseline control.

Figure 2: Scatterplots showing the correlations between composite SES and Mu-suppression factor scores. Higher scores = greater power in the Mu-band, indicating weaker Mu-suppression.
Figure 2: Scatterplots showing the correlations between composite SES and Mu-suppression factor scores. Higher scores = greater power in the Mu-band, indicating weaker Mu-suppression.

And when all was grasped and un-grasped, the correlation was evident, as seen in figure 2: lower socioeconomic status was associated with greater Mu-suppression, or greater empathic capacities.

As Varnum notes in the paper,

previous work using self-report and behavioral paradigms has suggested that working-class people are more attuned to others than are middle-class people. The present research provides the first neural evidence for a relation between Mu-suppression and social status.

So do higher-class people know they’re less empathetic than everybody else? A previous paper by Varnum and colleagues entitled Social class affects neural empathic responses suggested that they don’t. In that study, Varnum found that higher SES participants self-reported strong empathy, but in reality were again found to have lower results than those with a lower SES standing, suggesting that, according to Varnum, “those higher in status may not realize that they are actually lower in empathy.”

It may come as no surprise that a proper oligarchy runs on the fuel of its own delusions, but now we’re starting to see some of the early neuroscientific evidence.


  • Kraus, M. W., Piff, P. K., Mendoza-Denton, R., Rheinschmidt, M. L., & Keltner, D. (2012). Social class, solipsism, and contextualism: How the rich are different from the poor. Psychological Review, 119(3), 546–572.
  • Piff, P. K. (2014). Wealth and the inflated self: Class, entitlement, and narcissism. Personality and Social Psychology Bulletin, 40(1), 34–43.
  • Stellar, J., Manzo, V., Kraus, M. W., & Keltner, D. (2012). Class and compassion: Socioeconomic factors predict responses to suffering. Emotion, 12, 449–459.


About the author

Noah Hutton

Noah Hutton is a film director and curator, and was named a 2015 Salzburg Global Fellow in Neuroscience and Art.

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