How does the culture you grow up in reflect in your brain?
We are all different. We each have a different genetic lineage, a different upbringing, We live in different geographies, speak different languages, observe different social codes. That is our cultural diversity. Our humanity.
But how easy is it to use techniques such as EEG to show these kind of cross-cultural differences at the level of the brain? And can a relatively small number of self-selected participants recruited for these kind of studies do justice to the diverse array of individuals that represents a particular culture?
Yourself. As represented in your brain.
“Self-referential processing” is the term that neuroscientists often use to refer to studies of the self. fMRI experiments have shown that self-referential processing activates a network of regions along the midline (see here for a recent discussion on the topic). This is similar to the network activated when the brain enters it’s “default mode” – the mode associated with mind wandering and imagination (rather than attending to external, sensory stimuli).
Although fewer studies have explored self referential processing using EEG (see here for a review), the fact that alpha oscillations are associated with this “default mode” makes them a primary candidate for self-referential processing, and therefore a good place to search for cross-cultural differences in self perception.
In a collaboration between the Russian Academy of Medical Sciences and the Institute of Statistical Science Academia Sinica in Taiwan, Gennady Knyazev and colleagues explored cross-cultural differences in self referential processing on group sizes ranging from 48-60 participants. They used high density continuous EEG recordings together with sLORETA source analysis and related this to data from self-report questionnaires.
The results showed that thinking about yourself activated a network of brain regions which could be divided into a posterior “hub” – including the posterior parietal cortex, occipito-parietal junction, posterior cingulate, and precuneus, and an anterior “hub” – including the superior frontal gyrus and anterior cingulate cortex. Both these “hubs” were primarily associated with alpha band oscillatory activity.
By comparing across Taiwanese and Russian participants the researchers also showed significant cultural differences. Whilst Russian participants showed greater alpha activity in posterior “hub” regions when engaging in self-referential thought, Taiwanese participants showed greater activity in anterior “hub” regions.
This striking difference at first glance seems to suggest possible evidence for cross-cultural differences in the way the people think about themselves. A fascinating insight. But can 160 people from Taiwan and Russia really tell you how a whole population thinks?
Another recent study has also examined cross-cultural differences, this time looking at social norm judgements, and comparing participants in China versus the United States. The collaboration between researchers at the University of Michigan and University of Maryland, and Shihui Han from the University of Peking, explored whether your cultural upbringing influences the way your brain responds when you are presented with a scenario of a person violating a social norm. For example, performing a behavior which is considered inappropriate in that particular environment, such as dancing in an art museum.
The researchers used event-related potentials (ERPs) to examine how the amplitude of a particular evoked potential – the N400 – differed in the context of a social norm judgement task across the two cultures, testing on groups of 25 participants from each country.
Analysis of the data revealed that the brain response to social norm violations across central and parietal regions was equivalent across Chinese and American participants – both showing a significant N400 response to an inappropriate social behaviour versus an appropriate one. However Chinese participants also displayed this same N400 response across lateral frontal and temporal regions, whilst American participants did not.
To try and make sense of this difference, the researchers included other attitudinal and behavioral measures. Using this information, they suggested the broader N400 response to social norm violations in Chinese participants could be related to a greater belief of cultural superiority, increased levels of self control and cautiousness, and lower levels of creative thinking (as shown by the alternative uses task).
Again, a really interesting insight into differences between two groups of people from different countries, opening a door for further exploration of cross-cultural diversity.
Culture in the Brain
Can we truly understand how culture manifests in brain activity? Results from a small samples from different populations may provide provocative hypothesis but simply can’t be sufficient. It doesn’t get to the heart of what we really want to achieve when comparing across people from different cultural backgrounds.
Take the 25 Chinese people used in the study above. As a comparison, China has a population of well over 1 billion, spread over a geographically diverse terrain spanning nearly 10 million square km. You don’t even need to do the math.
To find true correlates of culture would require large scale EEG studies (think 10,000, even 100,000 or 1,000,000 participants). that takes participant profiling to a new depth to make sure we know as much as we possibly can about the people we are wiring up to the EEG.
That is the challenge. That is the opportunity. That is what the Human Brain Diversity Project is all about.