Acculturation is the process of social, psychological, and cultural change that stems from blending between cultures. The effects of acculturation can be seen at multiple levels in both the original (native) and newly adopted (host) cultures.
Historically speaking, acculturation is a direct change of one's culture through dominance over another's culture through either military or political conquest.
At this group level, acculturation often results in changes to culture, customs, religious practices, diet, healthcare, and other social institutions. Some of the most noticeable group level effects of acculturation often include changes in food, clothing, and language.
At the individual level, the process of acculturation refers to the socialisation process by which foreign-born individuals adopt the values, customs, norms, attitudes, and behaviours of the dominant host culture. This process has been linked to changes in daily behaviour, as well as numerous changes in psychological and physical well-being. As enculturation is used to describe the process of first-culture learning, acculturation can be thought of as second-culture learning. Since approximately one in four children in the United States live with at least one immigrant parent, this topic is worthy of understanding and discussing.
Scholars in different disciplines have developed more than 100 different theories of acculturation, but the concept of acculturation has only been studied scientifically since 1918. As it has been approached at different times from the fields of psychology, anthropology, and sociology, numerous theories and definitions have emerged to describe elements of the acculturative process. Despite definitions and evidence that acculturation entails a two-way process of change, research and theory have primarily focused on the adjustments and adaptations made by minorities such as immigrants, refugees, and indigenous peoples in response to their contact with the dominant majority. Contemporary research has primarily focused on different strategies of acculturation, how variations in acculturation affect individuals, and interventions to make this process easier.
Although the word "acculturation" was coined by J.W. Powell in 1880, the earliest record of acculturation can be found in Sumerian inscriptions from 2370 B.C. These inscriptions laid out rules for commerce and interaction with foreigners designed to limit acculturation and protect traditional cultural practices.Plato also discussed acculturation, arguing that it should be avoided, as he thought it would lead to social disorder. Accordingly, he proposed that no one should travel abroad until they are at least 40 years of age, and that travellers should be restricted to the ports of cities to minimize contact with native citizens. Nevertheless, the history of Western civilization, and in particular the histories of Europe and the United States, are largely defined by patterns of acculturation.
One of the most notable forms of acculturation is imperialism, the most common predecessor of direct cultural change. Although these cultural changes may seem simple, the combined results are both robust and complex, impacting both groups and individuals from the original culture and the host culture.
The first psychological theory of acculturation was proposed in W.I. Thomas and Florian Znaniecki's 1918 study, The Polish Peasant in Europe and America. From studying Polish immigrants in Chicago, they illustrated three forms of acculturation corresponding to three personality types: Bohemian (adopting the host culture and abandoning their culture of origin), Philistine (failing to adopt the host culture but preserving their culture of origin), and creative-type (able to adapt to the host culture while preserving their culture of origin). In 1936, Redfield, Linton, and Herskovits provided the first widely used definition of acculturation as:
Those phenomena which result when groups of individuals having different cultures come into continuous first-hand contact, with subsequent changes in the original cultural patterns of either or both groups...under this definition acculturation is to be distinguished from...assimilation, which is at times a phase of acculturation.-- 
Long before efforts toward racial and cultural integration in the United States arose, the main course of action was assimilation. In 1954, Milton Gordon's book Assimilation in American Life outlined seven stages of the assimilative process, setting the stage for literature on this topic. Later, Young Yun Kim authored a reiteration of Gordon's work, but argued cross-cultural adaptation as a multi-staged process. Kim's theory focused on the unitary nature of psychological and social processes and the reciprocal functional personal environment interdependence. Although this view was the earliest to fuse micro-psychological and macro-social factors into an integrated theory, it is clearly focused on assimilation rather than racial or ethnic integration. In Kim's approach, assimilation is unilinear and the sojourner must conform to the majority group culture in order to be "communicatively competent." According to Gudykunst and Kim (2003)  the "cross-cultural adaptation process involves a continuous interplay of deculturation and acculturation that brings about change in strangers in the direction of assimilation, the highest degree of adaptation theoretically conceivable." Interestingly, this view has been heavily criticized, since the biological science definition of adaptation refers to the random mutation of new forms of life, not the convergence of a monoculture (Kramer, 2003).
Thus, the term adaptation is used by Gudykunst and Kim to mean conformity to the coercive power (pp. 360, 371) or "mainstream culture." According to this definition, any attempt to maintain one's original values, beliefs, ways of thinking, feelings, or behaviors constitutes mental illness or "maladaptation" (p. 372). This is further emphasized by Gudykunst and Kim (2003), stating that the way of "upward-forward" evolution toward functional fitness and psychological health is for the newcomer to willfully "unlearn" and "deculturize" themselves (p. 380). Gudykunst and Kim proposed both psychotherapy and abandonment of all ethnic relations and associations with ethnic ties to help immigrants achieve "integrative" conformity (2003). Again, this is not integration but rather dissolution of the newcomer's original identity. According to Gudykunst and Kim (2003), increased disintegration is preferred, even if it leads to extreme distress for the immigrant. Ironincally, Gudykunst and Kim seemed to identify the concept of acculturative stress stating "even extreme mental illness [caused by "conformity pressure" p. 371] can be viewed as a process of a potentially positive disintegration that will be reintegrated with new material at a higher level" (p. 381).
No matter how unjust or cruel, Gudykunst and Kim (2003) argue that the host's way of thinking, feeling, and behaving constitutes the "higher level" of psychic evolution and any resistance to conform indicates that the immigrant is communicatively incompetent, immature, mentally ill (pp. 365, 372-373, 376, 381), weak (p. 369), irrationally aggressive or hostile (pp. 371, 376), lacking in self-control (p. 369), cynical (p. 380), pessimistic (p. 369), closed-minded (p. 369), simple minded (pp. 382-383) and "ethnocentric" (pp. 376, 382). Evolutionary progress for the individual requires the individual to "abandon identification with the cultural patterns that have constituted who one is and what one is" (p. 377).
In contradistinction from Gudykunst and Kim's version of adaptive evolution, Eric M. Kramer developed his theory of Cultural Fusion (2011, 2010, 2000a, 1997a, 2000a, 2011, 2012) maintaining clear, conceptual distinctions between assimilation, adaptation, and integration. According to Kramer, assimilation involves conformity to a pre-existing form. Kramer's (2000a, 2000b, 2000c, 2003, 2009, 2011) theory of Cultural Fusion, which is based on systems theory and hermeneutics, argues that it is impossible for a person to unlearn themselves and that by definition, "growth" is not a zero sum process that requires the disillusion of one form for another to come into being but rather a process of learning new languages and cultural repertoires (ways of thinking, cooking, playing, working worshiping, and so forth). In other words, Kramer argues that one need not unlearn a language in order to learn a new one, nor does one have to unlearn who one is in order to learn new ways of dancing, cooking, talking and so forth. Unlike Gudykunst and Kim (2003), Kramer argues that this blending of language and culture results in cognitive complexity, or the ability to switch between cultural repertoires. To put Kramer's ideas simply, learning is growth rather than unlearning.
Although numerous models of acculturation exist, the most complete models take into consideration the changes occurring at the group and individual levels of both interacting groups. To understand acculturation at the group level, one must first look at the nature of both cultures before coming into contact with one another. A useful approach is Eric Kramer's theory of Dimensional Accrual and Dissociation (DAD). Two fundamental premises in Kramer's DAD theory are the concepts of hermeneutics and semiotics, which infer that identity, meaning, communication, and learning all depend on differences or variance. According to this view, total assimilation would result in a monoculture void of personal identity, meaning, and communication. Kramer's DAD theory also utilizes concepts from several scholars, most notably Jean Gebser and Lewis Mumford, to synthesize explanations of widely observed cultural expressions and differences.
Kramer's theory identifies three communication styles (idolic, symbolic, or signalic ) in order to explain cultural differences. It is important to note that in this theory, no single mode of communication is inherently superior, and no final solution to intercultural conflict is suggested. Instead, Kramer puts forth three integrated theories: the theory Dimensional Accrual and Dissociation, the Cultural Fusion Theory and the Cultural Churning Theory.
For instance, according to Kramer's DAD theory, a statue of a god in an idolic community literally is god, and stealing it is a highly punishable offense. For example, many people in India believe that statues of the god Ganesh - to take such a statue/god from its temple is more than theft, it is blasphemy. Idolic reality involves strong emotional identification, where a holy relic does not simply symbolize the sacred, it is sacred. By contrast, a Christian crucifix follows a symbolic nature, where it represents a symbol of God. Lastly, the signalic modality is far less emotional and increasingly dissociated.
Kramer refers to changes in each culture due to acculturation as co-evolution. Kramer also addresses what he calls the qualities of out vectors which address the nature in which the former and new cultures make contact. Kramer uses the phrase "interaction potential" to refer to differences in individual or group acculturative processes. For example, the process of acculturation is markedly different if one is entering the host as an immigrant or as a refugee. Moreover, this idea encapsulates the importance of how receptive a host culture is to the newcomer, how easy is it for the newcomer to interact with and get to know the host, and how this interaction affects both the newcomer and the host.
The fourfold model is a bilinear model that categorizes acculturation strategies along two dimensions. The first dimension concerns the retention or rejection of an individual's minority or native culture (i.e. "Is it considered to be of value to maintain one's identity and characteristics?"), whereas the second dimension concerns the adoption or rejection of the dominant group or host culture. ("Is it considered to be of value to maintain relationships with the larger society?") From this, four acculturation strategies emerge.
Studies suggest that individuals' respective acculturation strategy can differ between their private and public life spheres. For instance, an individual may reject the values and norms of the dominant culture in his private life (separation), whereas he might adapt to the dominant culture in public parts of his life (i.e., integration or assimilation).
The fourfold models used to describe individual attitudes of immigrants parallel models used to describe group expectations of the larger society and how groups should acculturate. In a melting pot society, in which a harmonious and homogenous culture is promoted, assimilation is the endorsed acculturation strategy. In segregationist society, in which humans are separated into racial groups in daily life, a separation acculturation strategy is endorsed. In a multiculturalist society, in which multiple cultures are accepted and appreciated, individuals are encouraged to adopt an integrationist approach to acculturation. In societies where cultural exclusion is promoted, individuals often adopt marginalization strategies of acculturation.
Attitudes towards acculturation, and thus the range of acculturation strategies available, have not been consistent over time. For example, for most of American history, policies and attitudes have been based around established ethnic hierarchies with an expectation of one-way assimilation for predominantly White European immigrants. Although the notion of cultural pluralism has existed since the early 20th century, the recognition and promotion of multiculturalism did not become prominent in America until the 1980s. Separatism can still be seen today in autonomous religious communities such as the Amish and the Hutterites. Immediate environment also impacts the availability, advantage, and selection of different acculturation strategies. As individuals immigrate to unequal segments of society, immigrants to areas lower on economic and ethnic hierarchies may encounter limited social mobility and membership to a disadvantaged community.
On a broad scale study, involving immigrants in 13 immigration-receiving countries, the experience of discrimination was positively related to the maintenance of the immigrants' ethnic culture. In other words, immigrants that maintain their cultural practices and values are more likely to be discriminated against than those whom abandon their culture.
It should also be noted that most individuals show variation in both their ideal and chosen acculturation strategies across different domains of their lives. For example, among immigrants, it is often easier and more desired to acculturate to their host society's attitudes towards politics and government, than it is to acculturate to new attitudes about religion, principles, and values.
The large flux of migrants around the world has sparked scholarly interest in acculturation, and how it can specifically affect health by altering levels of stress, access to health resources, and attitudes towards health. The effects of acculturation on physical health is thought to be a major factor in the immigrant paradox, which argues that first generation immigrants tend to have better health outcomes than non-immigrants. Although this term has been popularized, most of the academic literature supports the opposite conclusion, or that immigrants have poorer health outcomes than their host culture counterparts.
One prominent explanation for the negative health behaviors and outcomes (e.g. substance use, low birth weight) associated with the acculturation process is the acculturative stress theory.Acculturative stress refers to the stress response of immigrants in response to their experiences of acculturation. Stressors can include but are not limited to the pressures of learning a new language, maintaining one's native language, balancing differing cultural values, and brokering between native and host differences in acceptable social behaviors. Acculturative stress can manifest in many ways, including but not limited to anxiety, depression, substance abuse, and other forms of mental and physical maladaptation. Stress caused by acculturation has been heavily documented in phenomenological research on the acculturation of a large variety of immigrants. This research has shown that acculturation is a "fatiguing experience requiring a constant stream of bodily energy," and is both an "individual and familial endeavor" involving "enduring loneliness caused by seemingly insurmountable language barriers."
One important distinction when it comes to risk for acculturative stress is degree of willingness, or migration status, which can differ greatly if one enters a country as a voluntary immigrant, refugee, asylum seeker, or sojourner. According to several studies, voluntary migrants experience roughly 50% less acculturative stress than refugees, making this an important distinction. According to Schwartz (2010), there are four main categories of migrants:
This type of entry distinction is important, but acculturative stress can also vary significantly within and between ethnic groups. Much of the scholarly work on this topic has focused on Asian and Latino/a immigrants, however more research is needed on the effects of acculturative stress on other ethnic immigrant groups. Among U.S. Latinos, higher levels of adoption of the American host culture has been associated with negative effects on health behaviors and outcomes, such as increased risk for depression and discrimination, and increased risk for low self-esteem. However, some individuals also report "finding relief and protection in relationships" and "feeling worse and then feeling better about oneself with increased competencies" during the acculturative process. Again, these differences can be attributed to the age of the immigrant, the manner in which an immigrant exited their home country, and how the immigrant is received by the both the original and host cultures. Recent research has compared the acculturative processes of documented Mexican-American immigrants and undocumented Mexican-American immigrants and found significant differences in their experiences and levels of acculturative stress. Both groups of Mexican-American immigrants faced similar risks for depression and discrimination from the host (Americans), but the undocumented group of Mexican-American immigrants also faced discrimination, hostility, and exclusion by their own ethnic group (Mexicans) because of their unauthorized legal status. These studies highlight the complexities of acculturative stress, the degree of variability in health outcomes, and the need for specificity over generalizations when discussing potential or actual health outcomes.
Researchers recently uncovered another layer of complications in this field, where survey data has either combined several ethnic groups together or has labeled an ethnic group incorrectly. When these generalizations occur, nuances and subtleties about a person or group's experience of acculturation or acculturative stress can be diluted or lost. For example, much of the scholarly literature on this topic uses U.S. Census data, however the Census mistakenly categorizes Arab-Americans as "White."  By doing so, this data set omits many factors about the Arab-American migrant experience, including but not limited to acculturation and acculturative stress. This is of particular importance after the events of September 11, 2001, since Arab-Americans have faced increased prejudice and discrimination, leaving this community with an increased risk of acculturative stress. Research focusing on the adolescent Arab American experience of acculturation has also found that youth who experience acculturative stress during the identity formation process are at a higher risk for low self-esteem, anxiety, and depression. 
Some researchers argue that education, social support, hopefulness about employment opportunities, financial resources, family cohesion, maintenance of traditional cultural values, and high socioeconomic status (SES) serve as protections or mediators against acculturative stress. Previous work shows that limited education, low SES, and underemployment all increase acculturative stress. Since this field of research is rapidly growing, more research is needed to better understand how certain subgroups are differentially impacted, how stereotypes and biases have influenced former research questions about acculturative stress, and the ways in which acculturative stress can be effectively mediated.
In situations of continuous contact, cultures have exchanged and blended foods, music, dances, clothing, tools, and technologies. Cultural exchange can either occur naturally through extended contact, or more quickly though cultural appropriation or cultural imperialism.
Cultural appropriation is the adoption of some specific elements of one culture by members a different cultural group. It can include the introduction of forms of dress or personal adornment, music and art, religion, language, or behavior. These elements are typically imported into the existing culture, and may have wildly different meanings or lack the subtleties of their original cultural context. Because of this, cultural appropriation for monetary gain is typically viewed negatively, and has sometimes been called "cultural theft."
Cultural imperialism is the practice of promoting the culture or language of one nation in another, usually occurring in situations in which assimilation is the dominant strategy of acculturation. Cultural imperialism can take the form of an active, formal policy or a general attitude regarding cultural superiority.
In some instances, acculturation results in the adoption of another country's language, which is then modified over time to become a new, distinct, language. For example, Hanzi, the written language of Chinese language, has been adapted and modified by other nearby cultures, including: Japan (as kanji), Korea (as hanja), and Vietnam (as hán t?). Another common effect of acculturation on language is the formation of pidgin languages. Pidgin is a mixed language that has developed to help communication between members of different cultures in contact, usually occurring in situations of trade or colonialism. For example, Pidgin English is a simplified form of English mixed with some of the language of another culture.
Food habits and food consumption are affected by acculturation on different levels. Research indicated that food habits are discreet and practiced privately, and change occurs slowly. Consumption of new food items is affected by the availability of native ingredients, convenience and cost; therefore, an immediate change is likely to occur.
Some anthropologists make a semantic distinction between group and individual levels of acculturation. In these instances, the term transculturation is used to define individual foreign-origin acculturation, and occurs on a smaller scale with less visible impact. Scholars making this distinction use the term "acculturation" only to address large-scale cultural transactions. Acculturation, then, is the process by which migrants gain new information and insight about the normals and values of the culture and adapt their behaviors to the host culture.
Most research seems to indicate that the integrationist model of acculturation will lead to the most favorable psychological outcomes and marginalization to the least favorable. An initial meta-analysis of the acculturation literature found these results to be unclear. However, a more thorough meta-analysis of 40 studies showed that integration was indeed found to have a "significant, weak, and positive relationship with psychological and sociocultural adjustment". There are many factors that can explain the differences in these findings, including how different the two interacting cultures are, and degree of integration difficulty (bicultural identity integration). These types of factors partially explain why general statements about approaches to acculturation are not sufficient in predicting successful adaptation. As research in this area has expanded, one study has identified marginalization as being a maladaptive acculturation strategy.
Several theorists have stated that the fourfold models of acculturation are too simplistic to have predictive validity. Some common criticisms of such models include the fact that individuals don't often fall neatly into any of the four categories, and that there is very little evidence for the applied existence of the marginalization acculturation strategy. In addition, the bi-directionality of acculturation means that whenever two groups are engaged in cultural exchange, there are 16 permutations of acculturation strategies possible (e.g. an integrationist individual within an assimilationist host culture). The Interactive Acculturation Model represents one proposed alternative to the typological approach by attempting to explain the acculturation process within a framework of state policies and the dynamic interplay of host community and immigrant acculturation orientations.