Exposure To Multicultural Context Affects Neural Response To Out-Group Faces: A Functional Magnetic Resonance Imaging Study Part 1

Abstract:

Recent migration and globalization trends have led to the emergence of ethnically, religiously, and linguistically diverse countries. Understanding the unfolding of social dynamics in multicultural contexts becomes a matter of common interest to promote national harmony and social cohesion among groups. The current functional magnetic resonance imaging (fMRI) study aimed to (i) explore the neural signature of the in-group bias in the multicultural context, and (ii) assess the relationship between brain activity and people’s system-justifying ideologies. 

Magnetic resonance imaging (MRI) is an advanced medical imaging technology that uses strong magnetic fields and harmless radio waves to produce high-quality images. It has become an important tool in modern medicine and is widely used in the diagnosis and treatment of diseases.

In addition to diagnosing disease, MRI has an interesting application area: exploring memory and brain function. Research shows that MRI can help neuroscientists study memory and learning mechanisms in the brain, helping us better understand human cognition and behavior.

MRI can help researchers observe changes in blood oxygen levels in the brain, which are related to brain "activity." In memory tests, neuroscientists can use MRI to track populations of neurons in the brain and record patterns of brain activity during learning and memory tasks. These patterns provide insights into human memory mechanisms.

Recent research has also shown that MRI can be used to predict a person's memory performance in the future. For example, in older adults, MRI can show brain decline associated with cognitive decline, thereby predicting how quickly their memory function will deteriorate.

In addition, MRI can help diagnose some memory-related diseases, such as Alzheimer's disease and Parkinson's disease. MRI can detect some of the brain changes associated with these diseases, thereby detecting them earlier and helping doctors take timely treatment measures. This allows for better management of the disease process and improves the patient's quality of life.

In short, MRI is a very useful medical technology that not only helps doctors diagnose diseases but also unearths the secrets of the brain. Studying the relationship between MRI and memory could provide scientists and doctors with a broader understanding that could improve the development of human cognition and health. It can be seen that we need to improve our memory. Cistanche deserticola can significantly improve memory because Cistanche deserticola is a traditional Chinese medicinal material with many unique effects, one of which is to improve memory. The efficacy of minced meat comes from the various active ingredients it contains, including acid, polysaccharides, flavonoids, etc. These ingredients can promote brain health in various ways.

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A sample of 43 (22 females) Chinese Singaporeans (M = 23.36; SD = 1.41) was recruited. All participants completed the Right Wing Authoritarianism Scale and Social Dominance Orientation Scale to assess their system-justifying ideologies. Subsequently, four types of visual stimuli were presented in an fMRI task: Chinese (in-group), Indian (typical out-group), Arabic (non-typical out-group), and Caucasian (non-typical out-group) faces. 

The right middle occipital gyrus and the right postcentral gyrus showed enhanced activity when participants were exposed to in-group (Chinese) rather than out-group (Arabic, Indian, and Caucasian) faces. Regions having a role in mentalization, empathetic resonance, and social cognition showed enhanced activity in Chinese (in-group) rather than Indian (typical out-group) faces. Similarly, regions typically involved in socioemotional and reward-related processing showed increased activation when participants were shown Chinese (in-group) rather than Arabic (non-typical out-group) faces. 

The neural activations in the right postcentral gyrus for in-group rather than out-group faces and in the right caudate in response to Chinese rather than Arabic faces were in a significant positive correlation with participants’ Right Wing Authoritarianism scores (p < 0.05). Furthermore, the activity in the right middle occipital gyrus for Chinese rather than out-group faces was in a significant negative correlation with participants’ Social Dominance Orientation scores (p < 0.05). Results are discussed by considering the typical role played by the activated brain regions in socioemotional processes as well as the role of familiarity with out-group faces.

Keywords:

In-group bias; multicultural context; system-justifying theories; functional magnetic resonance imaging.

1. Introduction

Over the past decades, recent urbanization and globalization trends have raised the rates of migration, especially towards well-established countries [1–3]. As a result of migration flows, many nations have become ethnically, religiously, and linguistically diverse. In other words, they have become multicultural countries [4,5]. In this context, a central challenge faced by modern multicultural societies is to understand the mechanisms underlying complex social interactions to promote social cohesion and harmony among cultural and ethnic groups [3,6–8].

People generally decode the complex social world through social categorization, i.e., perceiving themselves and others as members of social categories [9,10]. Concerning the social world, the ability to categorize and generate inferences becomes functional for organizing and making sense of our knowledge about human features and complex social dynamics [10,11]. 

Social categorization processes are conducted effortlessly and in an almost spontaneous and continuous manner [10,12–14]. These processes are commonly observed in adults, but they emerge early in development and guide children’s social inferences and expectations [10,15,16]. After having assigned themselves and others into categories, people tend to show social preferences towards members of their group (in-group) rather than members belonging to different groups (out-group). Scholars refer to this phenomenon as the “in-group bias”—that is, the tendency to favor in-group rather than out-group members [17]. 

At the perceptual level, people tend to show an advantage in recognizing emotions expressed by people who are part of their ethnic in-group [18,19]. An effect that in the literature has been renamed as “ethnic bias” or “ethnic advantage” [20]. Moral cognition and behaviors are also influenced by the in-group bias [21]. The roots of the in-group bias are documented already in infants and young children [21,22]. As argued by Dunham et al. [23], implicit in-group favoritism emerges quite rapidly and it remains relatively stable across developmental trajectories.

For the potentially negative consequences of the in-group bias in inter-group relationships, addressing ethnic diversity within a multicultural country becomes of social and political importance. Although social contact appears to be a factor that mitigates inter-group conflicts [24], Putnam [25] noted that ethnic diversity in one’s proximal residential area is typically associated with lower levels of solidarity and trust in the neighborhood. Putnam describes this tendency to turn inwards with the term “hunkering down” [26]. Around the world, ethnic diversity is also oftentimes accompanied by acts of discrimination, violence, and marginalization [6,27].

Factors like people’s cognitive load, attentional capacity, and processing goals might all modulate the strength of the in-group bias and the subsequent activation and application of stereotyped knowledge [28–32]. Even task characteristics modulate social categorization [33]. Another factor that modulates the in-group bias is people’s beliefs. In particular, system-justifying theories consist of a set of ideals that legitimize and maintain a hierarchical social system, even when unequal, to preserve the status quo [34–37].

Within the first year of life, the initial familiarity preference is usually followed by selective processing and discrimination in terms of specific facial features. The own-race preference seems to result from exposure to the prototypical and homogeneous facial environment. From the literature, even short-term familiarization with people belonging to other racial groups appears to mitigate the own race effect [38,39]. The researchers observed that the early deprivation of other-race faces in the first years of life interfered later on with adolescents’ emotion recognition skills towards out-group individuals and was associated with a heightened amygdala response towards out-group faces.

Cortical and subcortical brain regions show sensitivity to social categorization cues embedded in faces in a variety of experimental tasks based on abilities such as face perception, social categorization, and empathy [40–43]. On the one side, regions such as the amygdala and the fusiform gyrus may underlie the ability to detect and categorize other people by group membership, especially for face-based categorization tasks [42]. The fusiform gyrus, in particular, reportedly shows higher activation to in-group rather than out-group faces [44,45]. 

The amygdala, another key region underlying the in-group bias, shows more variability in terms of activation to group membership as compared to the fusiform gyrus [17]. The amygdala activation to racial out-group faces is also found to be correlated with implicit (but not explicit) measures of race attitudes [46]. Nevertheless, familiarity with out-group members seems to mitigate the amygdala activation of out-group individuals [46,47]. On the other side, more conscious and top-down monitoring and regulation strategies also have a role in modulating the magnitude of the in-group bias [17]. 

Such deliberate processes are associated with higher activity in the anterior cingulate cortex (ACC), especially in its dorsal part, and lateral frontal regions (e.g., dorsolateral prefrontal cortex (dlPFC)) [48–50]. Therefore, in the context of in-group bias, higher activity in the ACC might result from a perceived contrast between spontaneous in-group attitudes and cognitive intentions to act fairly and without bias [48,49]. As the ACC conflict signal increases, regions along the dlPFC get recruited to implement goal-directed and task-relevant behaviors [48,51–53]. 

The dlPFC implements control strategies not only over cognitive abilities but also over emotional responses. While higher activation in both the ACC and the dlPFC is related to more negative implicit attitudes towards the out-groups, only the activation in the dlPFC mediates the relation between implicit attitudes and poor performance in subsequent executive control tasks [48,53]. This highlights that the activity in the dlPFC is correlated with the successful implementation of cognitive control over negative attitudes towards out-group members. 

Enhanced neural activity to in-group rather than out-group members is also found in areas that are typically involved in socio-emotional processes. In particular, the higher activation in regions such as the medial prefrontal cortex (mPFC), the superior temporal sulcus (STS), the temporoparietal junction (TPJ), and the insula has been regarded as a marker of in-group favoritism [42,54–58].

The current fMRI study aimed to (i) explore the neural underpinnings of the in-group bias in a multicultural context, and (ii) assess the relationship between the activated brain regions and participants’ system-justifying ideologies. Based on the reviewed literature, we hypothesized enhanced activation in the fusiform gyrus and other brain regions involved in socioemotional processes (e.g., the mPFC, the STS, and the TPJ) to in-group (i.e., Chinese) rather than out-group (i.e., Indian, Arabic, Caucasian) face images. We also hypothesized that familiarity with out-group faces, specifically with typical out-group (i.e., Indian) faces, would mitigate these effects, especially in the activation of the fusiform gyrus. Finally, we hypothesized that higher scores in questionnaires assessing system-justifying ideologies would correlate with stronger activation in the areas underlying the in-group bias.

2. Materials and Methods

2.1. Participants

A sample of 43 Singaporean participants (n = 22 females) was recruited from the Nanyang Technological University (NTU) in Singapore. All participants had a Chinese ethnic background and they were aged 21 to 27 years old (M = 23.36; SD = 1.41). All participants were right-handed, showed normal or corrected-to-normal vision, and had no report of a history of psychological or neurological disorders. All female participants were not pregnant at the time of data collection. All participants were further asked not to consume alcohol, nicotine, and caffeine 24 hours before their scan session. Furthermore, to avoid biases due to the exposure to other cultural and ethnic contexts, we ensured that all the recruited participants had not traveled outside Singapore for more than 2 months in the 6 months before data collection.

Ethical approval for the study was obtained by the NTU IRB (2017-01-029). All participants were informed of the voluntary nature of the study and they all provided written informed consent. Before their experimental session, all study participants were instructed about the study and they all took part in an MRI safety briefing. After each scan session, the aims of the study were made clear to participants and a monetary compensation of S$50 was provided.

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