Cultural differences in human behavior have been evident for thousands of years. For equally as long, differences in cultural practices and values, such as self-construal style, or the varied manner in which individuals within specific cultures tend to view the self relative to others (as either individualist or collectivist) were attributed to or explained by differences in environment. Once the study of trait inheritance gained prominence in the mid-nineteenth century with the work of Mendel, genetic explanations added to environmental explanations of differences in behavior across cultures. However, it wasn’t until recently that researchers have come to realize that interactions across all levels of analysis – genes, brain, behavior, and environment or culture, provide the clearest understanding of and explanation for both cultural and individual differences (Han, 2012).
With the technological advancement of neuroimaging in general, and functional magnetic resonance (fMRI) specifically, recent studies have elucidated differences in neural substrates across cultures, and revealed that certain cultural values, such as self-construal, can in fact influence and shape the development of these neural substrates, in contrast to being passive expressions of them. Findings such as these have made evident the gap that exists in disciplines able to explain and appropriately house these issues. Subsequently, and in an effort to fill this void and further investigate the implications of these findings, elements of the fields of cultural psychology and cognitive neuroscience converged to form cultural neuroscience.
This essay provides an overview of cultural neuroscience, as well as some of its key conceptual and theoretical components. In addition, it will identify and discuss how culture can differentially affect the development of self-construal style to be either individualist or collectivist. Several differences in the neural substrates underpinning these behaviors and also affected by them will then be examined and discussed as well as the interaction of self-construal style and the specific portion of the Serotonin transported gene, 5-HTTLPR.
Most broadly, cultural neuroscience aims to investigate and describe the ways in which genetics and brain development affect culture, and equally so, how culture affects both brain development and gene expression (Chiao, 2013). In addition to its roots in cultural psychology and cognitive neuroscience, the foundational underpinnings of cultural neuroscience include certain theoretical and biological concepts essential to its understanding, two of which are neuroplasticity and culture-gene co-evolutionary theory (Han, 2012).
An intrinsic feature of the human brain, and a characteristic essential to cultural neuroscience is brain plasticity. Literature in both neuroscience and biology have shown that structural and functional changes occur within the brain as a direct result of environment, and that this malleability is the rule rather than the exception (Shaw & McEachern, 2001). Research has shown the occipital cortex, a brain region implicated in visual processing in sighted individuals, is activated and engaged during auditory processing in some blind individuals (Burton et. al 2002, Gougoux et al. 2009). Additionally, areas of the brain responsible for processing auditory information within hearing individuals are recruited for sign language for some individuals with auditory deficits (Nishimura et al. 1999). These findings imply the human brain has the ability to create functional and structural changes in order to accommodate an individual’s specific experiences and or environment pressures.
In addition to the concept of brain and neuronal plasticity, a key theoretical underpinning of cultural neuroscience is culture-gene co-evolutionary theory, also known as dual inheritance theory (DIT) or bio-cultural evolution. Culture-gene co-evolutionary theory posits that adaptive human behavior is a product of both genetic and cultural evolution and selection (Chiao, 2013). In the same way that genetic traits adapt and emerge within, and as a result of, specific environments, so do cultural traits. A widely used example of this phenomenon is the variance of lactose tolerance and intolerance across cultures. As a species, most humans are lactose intolerant (Laland, 1996). However, research has shown a strong correlation between lactose tolerance and the history of diary farming within certain populations (Laland, 1996). Within populations where dairy farming has had a significant historical presence, there is 90% lactose tolerance (Laland, 1996). In contrast, in cultures without this agricultural history, lactose tolerance is less than 20% (Laland, 1996). The implication is that as agricultural development progressed, and milk and dairy consumption by humans increased, so did genetic evolution within the familial lines of those consuming dairy, as more and more of them developed a tolerance. This example of the coevolution of culture and genetics culminates in a physiological presentation – being able or unable to break down lactose. Numerous other examples have been discovered in support of culture-gene coevolution theory, one of which highlights how culture influences the way individuals see themselves.
Individualism and collectivism are each cultural values, or schemas, that affect the way an individual views the self, others, and the self in relation to others (Chiao & Iidaka, 2009). This cultural characteristic is analyzed and measured using Hofstede’s cultural dimensions theory, a framework for cross-cultural analysis developed using factor analysis (Hofstede, 2001). Developed to examine the results of a worldwide survey of employee values by IBM in the 1960s and 1970s, the theory was one of the first that could be quantified, and is the tool most widely used to explain observed differences between cultures (Hofstede, 2001).
Differences in self-construal style, generally speaking, are evident across cultures and emerged from the divergent ancient philosophies of Socrates and Lao Tzu (Chiao & Iidaka, 2009). Many individuals from the United States and Western European cultures tend generally to possess a self-construal that is independent or individualist (Markus and Kitayama 1991). That is, they view themselves as relatively independent of others, as autonomous beings who are responsible for themselves, and who have loosely-knit ties to family, friends and larger, cultural groups. They prioritize their own value goals, ambitions, and beliefs over those of others, and place high value upon discovering and expressing their own unique, individual attributes (Markus & Kitayama 1991). Additionally, individuals with independent self-construals tend to describe themselves and others in relatively stable and general terms rather than with attributes that would change dependent upon the situation (Chiao & Iidaka, 2009). An example of this type of self-characterized description is, “I am faithful.” It implies a constant state, and does not allow for variation across circumstances.
In contrast, many individuals from Asian, African, and Latin American cultures tend towards an interdependent or collectivist self-construal, viewing the self as embedded in, or a part of, others. They emphasize attending to the group and its goals over the self and place high value on conformity, harmony and interdependence with others (Markus & Kitayama 1991). Individuals with an interdependent self-construal tend to refer to themselves and others using situation-specific attributes such as, “when I’m out of town for work, I am faithful to my wife” (Chiao & Iidaka, 2009). These descriptions of self-construal style and characteristics within east and west cultures refer to the statistical aggregate, and any one individual within any particular culture may have either an independent or an interdependent conceptualization of self-construal.
Self-construal develops, in part, as a result of the implicit and explicit messages dispensed from the culture within which one is raised and exists within, and greatly affects one’s experiential reality (Markus & Kitayama 1991). We know that self-construal directly and indirectly affects an individual’s physical, emotional, and cognitive behavior, and is implicated in regulating intra and interpersonal processes such as emotional regulation, self- relevant information processing, person perception, and social comparison (Markus & Kitayam 1991). Despite our fairly thorough understanding of the influence of culture on self-construal style and self-construal style on a wide range of behavior, the influence of self-construal style on brain and neural processes has been less clear.
Literature suggests medial prefrontal cortex (MPFC) activation varies when processing self-relevant information across differing self-construal styles (Chiao & Iidaka, 2009). FMRI research show subjects with individualist self-construal styles display greater MPFC activation when processing general self-descriptions as compared to collectivist self-construal style subjects who display greater MPFC activation when processing specific, or contextual self-descriptions (Chiao & Iidaka, 2009). Additionally, the degree to which a subject identified as individualist predicted MPFC activation to general self-descriptions, as degree of collectivism predicted MPFC activation to contextual self-descriptions (Chiao & Iidaka, 2009). These findings imply: the presence of two neural representations of self within the MPFC; and that differing cultural values, or in this case, self-construal styles, moderate recruitment of these representations (Chiao & Iidaka, 2009). Greater, explicit and general representations of self-knowledge (i.e. I am honest) were evident within individualists and greater contextual or circumstance-specific representations of self-knowledge (i.e. I am honest when speaking with my mother) were evident within collectivists (Chiao & Iidaka, 2009). Self-construal style is therefore implicated in the process of understanding, storing, assessing and retrieving information about one’s self.
Another fMRI study examined whether or not cultural priming either individualist or collectivist values in individuals who are bicultural would increase or enhance of those culturally congruent general or situation-specific representations of self (Chiao, 2009). Data in this study showed that bicultural individuals primed with cultural values of individualism by reading a story within which a leader was selected by merit, had greater activation in dorsal medial prefrontal cortex and the posterior cingulate cortex (PCC) when processing general self-descriptions (Chiao, 2009). In contrast, there was greater MPFC and PCC activation when processing situation-specific self-descriptions in individuals primed with collectivist values by reading a story in which a leader was selected based on relationship (Chiao, 2009). Culturally primed modulation of MPFC and PCC activation can be accounted for by heightened attention to and use of those self-representations or characterizations that align culturally (Chiao, 2009). Furthermore, these data provide evidence that two distinct neural representations for self exist as a result of cultural values of either individualism or collectivism rather than inherent differences in the brains of Easterners and Westerners (Chiao, 2009). The study is a clear example of the manner in which culture can shape the neural representations of one’s self and its relation to others.
In an effort to better understand how culture might influence gene expression, researchers have begun to examine the relationship between self-construal styles and specific genes. 5HTTPLR, the polymorphic region of the Serotonin transported gene, contains either a short (S) or a long (L) allele, each of which will elicit a different 5-HTT phenotype (Chiao & Blizinsky, 2010). In relation to individuals with the L 5-HTT allele, those with S alleles produce less protein, less mRNA, have higher levels of Serotonin in the synaptic gap, and are more susceptible to heightened anxiety, harm avoidance, fear conditioning, and depression when simultaneously exposed to environmental risk factors (Chiao & Blizinsky, 2010). Population genetics has produced several studies showing greater concentrations of S allele carriers (up to 80%) in East Asian countries in contrast to European samples (40-50%) (Chiao & Blizinsky, 2010). Research has shown that across 29 cultures, increased prevalence of S allele carriers within a population is a significant predictor of individualism or collectivism (Chiao & Blizinsky, 2010). This data shows that across geographic regions, heightened rates of S allele carriers within a population will predict lower prevalence of anxiety and mood disorders as a result of higher rates of collectivist cultural values, despite the previously identified propensity for anxiety in mood disorders in S allele carriers (Chiao & Blinsinsky, 2010). The implication is that collectivist values, such as increasing social harmony and interdependence, act as anti-pathogenic forces by lowering stress and protecting vulnerable individuals (S allele carriers) from the environmental risk factors known to cause anxiety and mood disorders (Chiao & Blizinsky, 2010).
Recent technological advances have allowed researchers to investigate all levels of analysis in a much more thorough manner than ever before. Subsequently, we have learned that above and beyond a genetic endowment, human behavior is influenced by a myriad of interacting forces, and can only be thoroughly understood through cross-level analyses. We have discovered that something as seemingly elusive as cultural values and schemas can directly influence human behavior, as well as indirectly by way of affecting genetic phenotypes. The advent of cultural neuroscience has allowed for these discoveries, and has created a discipline within which much more exciting research will take place.
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