Acculturation and Intercultural Learning of Missionaries, Their Families, and the Role of Women in the Christian Mission—A Review of Literature from 1954 to 2010

: This literature review summarises a wide range of empirical and systematic studies published between 1954 and 2010, including anthropological, cultural, historical, psychological, and sociological perspectives still underrepresented in cross-cultural communication and competence. Missionaries’ adaptation and acculturation, as well as of their families to new social and cultural environments and during reintegration at home are characterised by stressful experiences such as critical life events, premature termination, and upcoming retirements. Other studies highlight that certain personality traits and an ability to cope with psychological stress can predict the effectiveness of a mission assignment, e.g., spiritual and organisational commitment and expectations. Additionally, the review brings to light different role orientations of missionary wives, the psychological well-being within marriage, and the role of women in the Christian mission. Eventually, all ﬁndings will be subject to critical analysis and be instrumental in providing future research perspectives.


Introduction
Although missionaries acquire the capacities and competencies, as well as specific knowledge of the theory and practice of missions, by way of their profession and area of activities, little attention has been paid to the process of "adaptation" or "acculturation" or to "intercultural learning" (Weidemann 2007) in the Christian mission.Additionally, intercultural learning and acculturation as multidimensional constructs are related to psychological well-being and sociocultural adaptation (e.g., Sam 2006).Psychological research on missionaries' perception of stress and religious coping, loss of identity, and mental health problems during re-entry to their home culture has contributed new knowledge to the understanding of missionaries' self-perception and identity and their resilience (Herppich 2014;Selby et al. 2009;Tone 2015;Tone et al. 2020).A literature review is more than desirable to better understand what a cross-cultural mission means.This article deals with this specific mode of cultural exchange in the practice and research field of the Christian mission.As missionaries' intercultural learning and acculturation is intertwined with missionaries' mental health development before, during, and after their assignments, this article includes literature from both fields of research (e.g., Ng et al. 2013;Yoon et al. 2013).Still, the literature review is mainly conducted through the lens of the research perspective of intercultural communication and competence (Rings and Rasinger 2020).

Material and Method
For exploratory purposes, the literature review is restricted to journal articles, books, and other texts published in the English language between 1954 and 2010.The literature review was conducted as part of the authors' qualitative-empirical research (Arnold 2010),

Success Criteria and Effectiveness of Missionaries
In this subsection, missionaries' effectiveness and respective success criteria are evaluated.After a discussion of the method and framing of the relevant studies and of the difficulty of aptitude testing in the mission context, the success criterion of adaptation and critical events in the life and work of missionaries and their families are emphasised, before other criteria such as the "ideal missionary" and "spiritual and organisational commitment" are described.Eventually, the review brings to light the role orientations of missionaries' wives.

Aptitude Testing in the Context of the Christian Mission
In this context, diagnostic instruments have been developed which are appropriate for establishing the aptitude of a missionary for a mission placement, obtaining a prognosis of the success of their activities, and carrying out a continuous measuring and assessment of their capabilities during overseas activities (Deller and Albrecht 2007).Attempts have been made to establish markers and criteria for "aptitude testing" (Deller and Albrecht 2007) and measuring the effectiveness for international postings.This includes the questions of what constitutes the purpose of a mission placement and/or a successful mission posting, and which criteria define the "success" (frequently also described as "effectiveness") of a missionary's overseas placement.Therefore, not only is the preparation for an overseas posting of significance for the successful completion of a posting but personal attributes, interpersonal, and intercultural competencies should also be considered, because they influence success overseas and the choice of missionaries.The criteria applied for the choice and/or evaluation of success vary from study to study and are subject to the viewpoint of the researchers involved.The need for an aptitude test emerges for various reasons: the reduction of drop-out rates, improvement of the selection process, and strategic choice of staff (Ferguson 1983).However, in the selection and aptitude testing, the qualities tested in the missionaries to be recruited cannot reflect the whole palette of possibilities, challenges, and stresses in the mission field."Thus, it is dangerous to use the behavior of responding to a self-report inventory or the behavior in an interview or simulated situation to predict how a person will behave in a far different situation such as living and working in a foreign culture.From this point of view identifiable life history events occurring over years and observed behaviors over weeks and months in an actual, though perhaps temporary, cross-cultural situation are safer to use in predicting eventual cross-cultural adjustment than self-report scales and interviews" (Williams 1983, p. 23).
Success criteria such as "adaptation" or "acculturation" are regarded as less appropriate, as is the premature termination of an overseas placement since, in most cases, these are not directly attributable to the concrete situation of the missionaries affected (Deller and Albrecht 2007).
In establishing and defining criteria specific to mission placements, one is, however, confronted with the problem that high empirical content and strong theoretical elements are not currently available or, if empirical studies have been carried out, there is a general lack of validity in the findings of this research.This continues to be the case despite the numerous (questionnaire) studies-frequently commissioned by the missionary societiesabout missionaries' emotional involvement, financial losses, and personal fluctuations in missionary societies, and the many and various reasons for the termination of a mission posting (Britt 1983;Kennedy and Dreger 1974;Lindquist 1983;Williams 1983).The need for systematically determining aptitude and testing the effectiveness of missionaries has been seen, among others, from the perspective of the problems overseas postings bring with them.

The Success Criterion of Adaptation
It has been mentioned in various places that "adaptation" represents a complex, multilayered construct associated with "polyvalent" (Boesch 2001) connotations.Missionaries are regarded as having "adapted" when interested in the local host culture, independently amassing knowledge about the customs, traditions, and values of the host culture, and seeking contacts and friendships with members of the host culture to enrich their life convictions and personality through contact with a foreign culture (Williams 1983).Although it has repeatedly been emphasised that the capacity for adaptation ("cross-cultural adjustability") to the foreign cultural environment and handling and coping with cultural differences should be regarded as a decisive factor in the success of overseas postings (Williams 1983), there is a lack of corresponding studies regarding the research field of the mission.
In aptitude testing and selection of missionaries, recourse is often made to instruments and test procedures developed and implemented in other occupational areas and fields of application.For example, use is made of the Intercultural Development Inventory (IDT), based on Bennett and Bennett and Bennett's (1993) Developmental Model of Intercultural Sensitivity (DMIS) and tests attitudes to other cultures on the spectrum between ethnocentric and ethnic-relative perspectives.Through answers to 50 questions measured on a scale of seven degrees, it can be ascertained what degree of cultural adjustment this candidate has reached at a given time.Reference is made at several points to problems about empirical validation, determining distinctions between normative stages of development, and their applicability to various target groups (Deller and Albrecht 2007).This test instrument is, however, used for various reasons for aptitude testing among missionaries.Sheffield (2007) provides a developmental model in contrast to other criterion-related models, (2) represents an instrument for identifying the current stage of development of a missionary's intercultural skills, (3) enables documentation of development towards a higher level of intercultural sensitivity, and (4) allows adaptation to a wide variety of occupational and professional areas for developing intercultural sensitivity.

Critical Life Events, Premature Termination of Missionary Placements, and Retirement of Missionaries and Their Families
Frequent changes in both personal and professional spheres mark missionary work.These changes can often lead to problems when there is a need to change the nature, extent, and location of the activity and when a new task with a possibly even greater area of responsibility is in prospect.Besides strategic management and staff development open to intercultural questioning (Deller and Kusch 2007), the pathway into the mission on which missionaries embark is also frequently characterised by changes in the family sphere.Sometimes, staffing decisions by the organisation sending the missionaries out even coincide with biographical events and far-reaching "critical life events" (Filipp and Klauer 1991) which various phases of life bring with them (Carter and McGoldrick 1989;O'Donnell 1987).
One of the main problems threatening the success of international missionary postings is the relatively large number of missionaries who either terminate their placement prematurely or leave the whole mission service altogether, placing pressure not only on the missionaries affected but also on the churches and missionary organisations which send them out.As in other occupational fields, the number of terminations of missionary placements is difficult to capture in figures.Lindquist (1983) estimates that approximately 10%-50% of missionaries sent out for the first time break off their mission postings prematurely within a year.There are many reasons for the break, linked to health, relations with the church sending them out, the availability of continuous financial support, socio-cultural and socio-religious conditions in the host culture, the political situation in the host country, the relationship with other missionaries, relationships between the mission leadership and administration, relations with local, regional, and national churches, families, partnerships, and personal life history (Williams 1983, pp. 18-19).Children of missionary families are also affected by the premature termination of a mission placement (Bretsch 1954;Hsieh 1976).The reason is, in the case of most missionaries, associated with a feeling of bearing personal blame for it, and often leads to a lower degree of self-confidence, accompanied sometimes by psychological disorders.Gardner (1987) studied the reasons for terminating a mission posting among Wycliffe missionaries.The missionaries were compelled to end their service with Wycliffe for various reasons (Gardner 1987, pp. 310-11).The reasons given for the termination were frequently only a few of many possible ones connected with specific personality characteristics and not only with the missionaries' specialist aptitudes.There were frequent complaints about a lack of biblical knowledge and/or the capacity to make use of spiritual resources necessary to make decisions, defuse conflicts, and achieve personal goals.Possibly, too, a weak feeling of self-worth, occupational stress, and lack of job satisfaction led to the termination of the mission posting.Stress and frustration are admittedly present as a rule in most cases of the termination of activities but are not, however, mentioned as a reason for ending them.
3.1.4.Correspondence to the Ideal "Missionary Personality" as a Criterion of Success Among the studies concerned with the success criterion of "missionaries' personality" is the development of a prognostic tool to evaluate typical missionary personality traits in the work of Kennedy and Dreger (1974) and the description of psychological skills and communicative and interpersonal competencies in that of Cureton (1983).The typical ideal personality profiles described can be confirmed and expanded by, among others, the studies by Ferguson (1983) and Diekhoff et al. (1991).Additionally, Dillon (1983) has examined the connection between the traits required in the typical ideal and missionaries' career choices.The most important findings are presented in what follows.
In their study, The Missionary in Action-A Descriptive Checklist (MINA), Kennedy and Dreger (1974) developed a prognostic tool designed to examine a profile of requirements based on typical personality traits when establishing aptitude.Helped by this "checklist", it was also possible to determine behaviour-related traits in connection with missionaries' personal and social relationships.Additionally, an extensive questionnaire was developed in an empirical study which includes essential information about the foreign cultural context of the mission field to discover important and necessary criteria and/or standards by which to measure the effectiveness and capability of mission staff.These criteria of success specific to missionary work were supplemented by general criteria for evaluating the effectiveness of missionaries.A total of 567 participants from various professions and occupations were questioned, of whom 137 were missionaries who belonged to the Methodist Church in the Philippines or the American Baptist, Episcopal, or Lutheran Church and were on a mission placement in the Philippines, had completed their posting, or had interrupted it.The remaining 430 persons mostly belonged to the group addressed by the mission.In addition to the missionaries, 10 staff leaders were questioned.A personal profile for every missionary was created from the completed questionnaires.
The success criteria could be only partially developed in this study.The MINA checklist is only a by-product of the study but represents a combination of expert opinions and evaluations by the staff responsible for sending missionaries out and those with responsibilities for staff within the home institutions.This questionnaire was successfully tested in sending out missionaries to the Philippines.Helped by the MINA checklist, 11 factors were determined which possess substantial prognostic validity and satisfactory reliability and describe various social and occupational relations between missionaries and members of the host culture.These factors were described as an ideal profile of the requirements for a missionary.Among these are a capacity for empathy, a good supply of information about the local and host cultures, project and team skills, the ability to nurture others' personality development, authenticity and a capacity for reflection, a sense of conviction in one's actions, ability to adapt to the host culture and to contact those belonging to it, and competence in caring for the social needs of other missionaries.Despite the relatively high number of those tested and their significant preferences, only limited and somewhat vague pronouncements can be made about the effectiveness and capability of the missionaries; the prognostic quality of the factors disclosed needs to be tested in further empirical studies.Cureton (1983) described how relevantly success criteria for missionaries were determined using the evaluation of the Mental Health and Missions workshop, based on an investigation of 44 missionaries, and members of health care professions with and without the experience of missionary postings.This study has an ex-post-quasi-experimental character.Three groups were compared with one another in terms of cognitive, physical, and psychological skills, capacities, personality traits, and interpersonal competencies on a scale of priorities.Astonishingly, all three groups agreed in their judgment on the essential criteria for success for missionaries.A "successful" missionary must, according to Cureton (1983, pp. 200-1), fulfil the following aptitude criteria: "(a) To influence others in favour of a point of view by verbal communications and by demonstrations; (b) to gather, collate, and classify information about date, people, and things; (c) to start, stop, control, and adjust various machines and equipment designed to help them accomplish their task (this would involve setting up and adjusting the machine as work progresses as well as controlling the equipment which involves monitoring gauges, dials, and turning of valves); (d) to make arithmetic calculations involving fractions, decimals, and percentages; (e) to use language effectively in writing routine business correspondence, understanding technical manuals and verbal instructions, interviewing applicants to determine the work best suited for their abilities and experiences, and conducting some opinion research surveys involving stratified samples of a population; and (f) to devise a system of interrelated procedures applicable to solving practical everyday problems and dealing with a variety of concrete variables and situations where only limited standardization exists." According to this extraordinary characteristic, job performance skills include, in terms of a mission agency's expectations, not only oral and written communication skills, basic literacy skills, and knowledge about social research techniques, but also more practical experiences which go well beyond the "missionary competencies" (in the proper meaning of the word) such as controlling technical machines and equipment and dealing with everyday problems.About the latter, this reminds us of the wisdom of the selection criteria and expectations of the mission agencies under these conditions.
A study by Ferguson (1983) describes the selection process and determination of aptitude in the Link Care Counseling Center (Fresno, CA), which represents the many initiatives for psychological and health advice and support for the staff of various missionary organisations as well as preparation for and support during missionary postings.Several studies of the literature and conversations with experienced missionaries have yielded the information that a successful missionary must have these traits and characteristics: adaptability, teachability, flexibility, modesty, integrity, readiness to cooperate with others, interpersonal communication skills, the ability to listen, and the capacity to build up partnerships and relationships (Ferguson 1983, pp. 26-27).Aptitude testing as standardised psychometric tests and questionnaires takes place once before the posting and a second time during the placement.The aptitude test consists of four stages: first, questions are put to the individual about demographic data, training needs, overseas experiences, and dealing with several critical interactive situations; then, about interpersonal relationships and personality factors; and finally, the potential is tested for combining personal interests with the future posting and working environment (Ferguson 1983, pp. 27-28).
In the study by Diekhoff et al. (1991), 88 US-American missionaries were questioned from various interdenominational and Protestant missionary institutions.Respondents were stationed in eleven cultural settings, had received four-week preparatory training, and ranged in age from 20 to retirement age.Participants in the study were asked to place 25 characteristics in such a way on a ranking list (producing a rating and/or ranking order) so that this list of priorities, in their opinion, represented the combination of qualities in an ideal missionary.An analysis of the factors in these personality traits produced the finding that no specific personality profile permitted a valid prediction of missionaries' effectiveness and ability to adapt across different cultures.The personality traits differed significantly from one culture to another, e.g., in the case of the two factors "open-ness/integrity" and "anxiety/shyness".No significant cultural differences were found for the other two factors of "social skills" and "personal energy".The Multidimensional Scaling (analysis of similarities) enables the eleven foreign cultural locations of the missionaries' placements into two groups, "Muslims" and "East Asians", which differed in the trait of "anxiety/shyness".This meant that because of the diversity of missionary postings, different qualities, demands, and assumptions might be required of a missionary.From the authors' viewpoint, a need arose for the precise definition of intercultural measures to qualify staff to prepare for international postings: "First, to a limited degree, the training of missionaries may be fine-tuned to be consistent with the kinds of culture-specific and ministry-specific demands missionaries will face in their overseas ministries.Second, knowing these demands may enable missionaries to select ministries most consistent with their own preferences, personalities, and personal styles.Finally, knowing a little about a ministry prior to placement can provide missionaries-in-training with a frame of reference to guide the direction of their adaption.After all, effective cultural adaption ultimately involves learning about and accommodating oneself to that culture" (Diekhoff et al. 1991, pp. 184-85).
Most studies on missionary aptitude testing are based on personality as a predictor of success.The Minnesota Multiphasic Personality Inventory (MMPI) is used relatively often.This test was used, for example, in Dillon's study to clarify the relationship between personality traits and a missionary's choice of a career.One aim of the study was to indicate evidence of the connection between personality and the time spent practicing an occupation as a career pattern among missionaries (based on the independent variables of gender, age, education, and the timing of the test).A total of 827 Protestant missionaries aged between 25 and 66 serving with American overseas missions and were undergoing preliminary medical examination for acceptance into the missions or were on home leave were investigated.These questionnaires were presented to potential missionaries over 30 years.As for the relationship between personality and choice of career, these connections emerged: The evidence from the first question suggested the average missionary projected the best appearance.The male missionary avoided facing reality, but the female missionary faced up more squarely to reality and was more rugged in handling difficult situations.
In comparison with the normal population, the average missionary struggled more against problems encountered in the field and worried more.The missionary was somewhat a visionary and a little impractical but had a strong ability to rebound from emotionally stressful problems.Missionaries characterised themselves as leaders who were decidedly independent of others and dominant in most situations.They evidenced a lack of control over symptoms that arose because of stress, although this characteristic may reflect a discrepancy between the religious beliefs of the missionary and the content of the items on the MMPI (Dillon 1983, p. 215).
Additionally, it was established that long-term missionaries were less liable to tell untruths and had to struggle more vigorously with feelings of insecurity than short-term missionaries.It was also concluded that missionaries varied substantially from the norm population in the MMPI test on all the scales examined, and thus possessed a significantly different aptitude profile (Dillon 1983, p. 215).
3.1.5.The Success Criteria of Efficiency and Ability to Cope with Psychological Pressure: The Influence of "Spiritual" and "Organisational Commitment" and Expectations Independently of the concrete professional and occupational area, an individual is always sent into the mission field to pursue a specific activity and perform the tasks associated with their occupation to the best of their ability (Deller and Albrecht 2007, p. 742).Efficiency as a criterion of success for the mission represents only one singular aspect, which depends directly on various predictors.Efficiency and ability to withstand psychological pressure during a mission placement is, for example, associated to a high degree with "spiritual" (Barnett et al. 2005) and "organisational commitment" (Trimble 2006), and with (culture-specific) expectations (Barney and Chu 1976).Specific psychological and spiritual predictors of success for short-term mission postings, a placement area hardly ever made the subject of research, have been studied and empirically determined by Barnett et al. (2005).In their study, a replication was achieved of the results of earlier studies employing various psychological tests, including the Minnesota Multiphasic Personality Inventory (MMPI Version 2) to evaluate the psychopathology of partners in the survey before placement in the mission field, the Attachment and Object Relations Inventory for self-assessment in the theory of object relations, and the Spiritual Assessment Inventory for assessing the research partner's spiritual development.The study involved 40 students from the faculty of International Studies at a US American Christian liberal academy of the humanities aged between 18 and 25, who had completed an internship of at least six weeks in a missionary society, developmental, or charitable institution and had shadowed local missionaries at their work for short periods in international encounters as language teachers, evangelists, assistants in missionary organisations, hospitals, orphanages, and youth groups.An amount of 85% had been socialised in the USA, and over 70% gave their cultural origin as "Caucasian".The study was conducted over two academic years.All participants were recruited during a two-week preparatory seminar and received the questionnaires and test sheets about a month before departure (with some variations in the second year).The mentors were also questioned about the efficiency and psychological resilience of the interns before the latter's return.
The findings of this study show that various factors influence the efficiency and psychological resilience of short-term missionaries on international placements and can thus support or jeopardise their effectiveness and psychological adaptation (Barnett et al. 2005, pp. 36-38): The evaluation of psychological resilience is closely linked to their general psychopathology before the posting, while efficiency is particularly influenced by general psychological symptoms before departure, the quality of the personal relationship with God and/or "spiritual commitment", and the quality of relationships with others (including those in authority or others of one's own age).In particular, missionaries who experience greater social alienation, have more conflicted relationships with authority, and have greater disappointment in their relationship with God need more supervision to work in a cross-cultural setting.As splitting in the relationship with God increases, and as missionaries' relationships become increasingly characterised by dependency, they have less ability to effectively perform their job responsibilities with no direct supervision.They also have greater satisfaction in accomplishing their goals when they have better-quality relationships with peers.Missionaries report having better relationships with their team members when they have more awareness of God, whereas supervisors are more likely to assess them as having poorer interpersonal relationships when their relationships with God are characterised by splitting and disappointment.As the degree of psychological symptomatology and conflict with authority increases, missionaries' capacities to incorporate and respect the values of their supervisors and host culture decreases (Barnett et al. 2005).
Despite various limitations regarding its validity because of the small group examined and the problems of the testing procedures employed, the results of this study show that a direct link exists between the religious and/or spiritual demands and psychological stress and/or harm among missionaries, and which factors are decisive for the success of their activities during a posting.Barnett et al. (2005, p. 37) consider, based on these findings, that it is necessary to carry out psychological and spiritual tests during the selection of candidates for short-term missionary placements and corresponding occupational analyses during the posting so that more precisely targeted support can be offered for the missionaries' psychological and spiritual resources.Such tests can include not only items and criteria related to task and job performance in the mission but also more intrapersonal aspects such as psychological well-being, personal relationships with God, and interpersonal aspects such as creating and maintaining relationships with others, dealing with ambiguity, conflicts, and authority.In addition, the organisational commitment and job dedication of the missionaries also affect their work performance (e.g., Allen and Meyer 1990).Another survey study by Trimble (2006) shifts the focus to the impact of job security on the dedication of missionaries to their sending organisation, their job satisfaction, and personnel turnover in different age groups or generations.
3.1.6.Role Orientations of Missionaries' Wives and Psychological Well-Being within the Marriage Partnership as a Criterion of Success Examination of the marriage partnership among missionaries is also of particular interest in (religious-)psychological, and empirical theological research, and is a success factor in mission work.This form of partnership also leads to several important aspects and conclusions about the satisfaction of missionaries and, thus, to the success of the mission placement.The identification of problems and/or factors that may influence a missionary marriage also indicates that these partnerships differ markedly from those in other areas of life.The greatest challenges for the missionary couple are the change of location, leaving behind family, friends, and the previous workplace, and going into another, foreign culture and the living conditions associated with it, which is often associated with psychological problems, stress, and so-called "culture shock".
The connection between role expectations and the well-being of married women in the mission was also the object of a study by Crawford and DeVries (2005), in which a questionnaire was used with open and closed questions to measure well-being, satisfaction with their lives, self-worth, health, and emotional stress during the mission placement.The classification of roles by Bowers (1984) could be supplemented by two further roles, "direct worker" and "support worker".In this study, 153 long-term missionaries' wives from the Africa Inland Mission participated, aged between 26 and 68, who had been stationed for an average of 13 years either in cities or in rural areas in Africa or were stationed in their homeland, the USA or Canada.Over 60% of the women possessed academic qualifications.
The analysis showed an ambivalent picture: the experiences of most missionaries' wives were predominantly positive and associated with spiritual and religious experiences.The missionaries' wives identified themselves according to Bowers' classification (Bowers 1984, p. 6) either as "homemaker", "background supporter", "team worker", or "parallel worker", in which role conflicts and disappointing role expectations occurred as especially frequent problems.In the authors' opinion, this was confirmed by answers to the open questions: "In an analysis of the data using this new classification Direct Workers were found to have a lower level of emotional distress than Support Workers" (Crawford and DeVries 2005, p. 187).For missionary organisations, this demonstrated the need to include wives in preparation for posting and to prepare them for criticism of the understanding of their role in their respective host cultures.
Although women's roles in missions vary widely across cultures and countries, they have historically played a crucial role in expanding the reach and influence of missionary work.Women who participate in missions often have important roles and responsibilities beyond being marital partners (e.g., Grimshaw and Sherlock 2021).Therefore, Section 3.2 will specifically highlight the changing role of women in missions.

Women's Mission Work and the Emancipation of Women
The many-sided experiences of women in missions show that active participation throughout various historical missions was planned by them to a considerable degree but was frequently also carried out by them on their initiative and with their scope for action.Additionally, research about women is a relatively young field of study in mission scholarship.The special role of women in the (Christian) mission has only advanced to become an independent theme of research in the English-language literature since the late 1970s and in German-language literature since the mid-1980s and has since found its way into the study of history, religion, anthropology, and sociology, as well as other scholarly disciplines (Bowie et al. 1993;Keim 2005;Lienemann-Perrin 1995;Seeliger 2008).Thematically, these perspectives are oriented towards historical women's studies with a direct link to the aspect of the Christian mission.Researchers endeavour to "study women in the mission movement and find out about their self-image as well as their experiences in the struggle for self-assertion and scope for action" (Lienemann-Perrin 1995, p. 230, transl.by author).This was generally connected with the normative aim of improving social conditions and women's rights."Women's mission" is inseparable from "women's emancipation" (Kaufmann 1988;Keim 2005) and "Protestantism" (Hutchison 1992).
Women who served as missionaries often found themselves in unfamiliar and challenging situations while living in a foreign culture and learning a new language (Grimshaw and Sherlock 2021): (1) As their participation was often restricted to supportive roles such as teachers, nurses, or wives, they gained valuable experiences in cross-cultural exchange beyond their roles as marital partners.(2) Through their work, they gained valuable skills in communication, problem-solving, and community building, which were not only relevant to their missionary work but also transferable to other areas of their lives.(3) Additionally, women on missions often provided a strong model of female leadership in societies where women had limited access to positions of power.Thus, while women on missions were often limited by gender roles and expectations, their experiences in missionary work were significant in expanding their horizons and contributing to the larger cause of promoting cultural exchange and understanding.
However, women's missionary work is not a new phenomenon, or even a previously unknown one.Before 1800, Protestant women-besides the few wives who accompanied their partners in the role of a nurse for children, husband, and home-exercised only a limited influence on the worldwide mission movement.Various studies prove that as early as the beginning of the 19th century-in the great revival movement (1800-1830)outstandingly educated women from the bourgeois milieu and/or the upper-middle classes from North America were traveling, either as wives or alone, to the most remote parts of the world under the protection of Christian missions.Of those missions, the female missionaries from the American Board of Commissioners of Foreign Missions were undoubtedly among the best-known (Bowers 1984;Wollons 2003).These women were mostly-as for their travels-inexperienced, and had been infected by the tales of adventure, exotic imaginings, and longings of the predominantly male missionaries of their day.Missionaries differ from travellers in their "hybrid identity" (Bhabba 1994): "They had a job to do that required a level of commitment and confidence that is unasked of the casual traveller.In the end, the missionaries did not stay because they were successful at bringing the heathen to Christ.At this, they were decisively unsuccessful.They stayed because they became bilingual, bicultural, and embedded in the daily lives of their communities.Each was deeply committed to the education of girls and women, and to the improvement in the lives of individuals [sic] The missionaries who stayed were able to maintain the high standards of education, while incorporating the fundamental values of the local cultures" (Wollons 2003, p. 69).
These women often underwent unexpected transformations from evangelists to teachers (e.g., in the struggle against illiteracy and the education and upbringing of children), from teachers to political activists (e.g., opposing slavery and serfdom and advocating women's rights and monogamous marriage), and from self-sacrifice to self-presentation (e.g., as authors and researchers).The connection between the Protestant confession and the increasing education opportunities for women created unimagined possibilities for these women not only to devote their own lives to the service of their neighbours but to venture on uncommon adventures in distant lands.It can be stated with certainty that only at the beginning of the 20th century were the foundations and framework established for this uniquely influential transnational and/or international phenomenon, which began in English-speaking countries and took root a little later in continental Europe and some non-Western missionary societies. 1 It is less well-known that it was precisely unmarried women who presented missionary work with new challenges.They generally had professional training of their own, were paid their salaries as regularly appointed co-workers in the missions, and demanded the right to speak and to vote in missionary assemblies (Keim 2005, p. 13).This often led to problems with the leadership of missionary societies.Women were concerned with nothing less than their "equal right" in missionary work, and avoidance and rejection of the social stigmatization and hierarchical degradation of women in the historic Christian churches, which were overwhelmingly characterised by patriarchal social structures, which can be described as an "emancipator act" (Keim 2005).The original idea of women's mission work, however, was different, as a decisive element in their investigations was placed out of reach of male missionaries in their postings in various Asiatic countries.This was the sphere of women, which led at first to missionaries being sent out by Protestant missions with their wives, but later to single female missionaries also being dispatched.Thus, as early as the 19th century, the call went up for unmarried women, who were stronger than married women who were mostly taken up with the demands of raising children and running a household, and who could make their time available to this task of building up women's work.Additionally, there was the idea that native Asiatic women were subject to a lot unworthy of them because of the social conditions of the time, such as suttee, killing female infants, exposure of girls, and hard work by women who were often regarded as the "slaves" of men.This called the Western mission to the plan of proclaiming the gospel of freedom to these women and improving their living conditions by doing so (Keim 2005, p. 14).
This was not simply received without criticism in post-colonial discourse (Kaufmann 1988).Like other cultural travellers, women missionaries also brought their own Western culture and value orientations, their convictions and attitudes, as well as their skills and willingness to change their identity based on the experiences they underwent (e.g., Wollons 2003).They often did not reflect on their motivation for converting foreigners and others.They saw themselves as driving motors of change."But the fact is not generally known that English and American were also represented in this body, and for their part contributed to strengthening women's work in the mission field and its leadership at home, the so-called home base.Concerning their emancipatory endeavors within missionary work, these women achieved astonishing results: on the one hand, their active sympathy and dedicated speaking at ecumenical world mission conferences contributed to convincing representatives of German-speaking mission societies that women too could speak in public and make an independent contribution to missionary work" (Keim 2005, p. 16, transl. by author).
In the edited volume by Bowie et al. (1993), a confrontation also occurs with the ambivalent history and reality of women's missions from the end of the 18th and beginning of the 19th century to the present day and from Western, Asiatic, and African perspectives, helped by various approaches to research from different disciplines (e.g., from the perspectives of social anthropology, history, religious studies, and literary studies).

Acculturation and Learning during Periods of Residence Abroad
Berry and Sam (1996) subdivided the term "acculturation" into three perspectives: "changes in behaviour", "acculturation stress", and "psychosocial consequences".The terms "adjustment" or "adaptation" were used based on the background of the discipline and the research perspectives chosen (Anderson 1994;Black et al. 1991;Ward and Kennedy 1996).Acculturation is understood as the "individual (psychological) reaction" (Weidemann 2007) to "cultural contact", which, over time, can lead to a stable equilibrium between the self and the environment (Boesch 2001) in the sense of an adaptation to the host culture and a feeling of well-being within it (Berry 2006), proceeding from an openness to the process of acculturation and its possible consequences (Berry and Sam 1996).Previous research into acculturation has primarily been concerned with the processes of transformation and possible consequences that longer-lasting "cultural contacts" bring in their wake. 2Alongside diplomats, refugees and immigrants, and others, students, scholars, military personnel stationed overseas, development helpers, economic experts, and management staff (also called "sojourners"; Ward et al. 2001) belong to typical groups studied in this area of research.
As has been shown, the description and explanation of valid "predictors of success" for sending missionaries to other countries have been central to these studies since the middle of the 20th century, predominantly from personal economic and socio-psychological perspectives.Frequently cited as a predictor of success alongside specialist qualifications, and the connection between "cultural adaptation" and "achievement" and/or "effectiveness at work" in the case of the person deployed, "cultural adaptation" can only be adduced to a limited extent as an objective measure in overseas placements (Parker and McEvoy 1993).For scientific research into acculturation, the benefits and success of foreign studies in international students were traditionally of particular interest (Ward et al. 1998).Several problems are associated with this limited perspective.Among the problematic features are the precise definition of terms, the operative use of corresponding scales of measurement, the validity and reliability of the results found in the various empirical studies, and the one-sided orientation towards the verification and glorification of "overseas success" (Weidemann 2007) of missionaries deployed abroad.Multi-factorial cultural adaptation models are widely accepted in which, for example, adaptation is measured and interpreted based on satisfaction and integration in the workplace, capability, and interaction with members of the host culture, and other general conditions in the host country (Black et al. 1991), or about the two categories of "psychological" and "socio-cultural" adaptation (cf., among others, Ward and Kennedy 1996).Specific psychological models of acculturation, characterised by a certain "openness of results" about possible consequences of cultural contact (Weidemann 2007), place a stronger emphasis on the "moderating factors" of these "processes of change" of both an individual and collective nature and conditions of "cultural contact" as well as their "results".Though processes of cultural adaptation have been examined based on intercultural encounters from various research perspectives, the aspect of missionary activity and missionary communication represents only a peripheral marginal phenomenon in the theoretical concepts developed in different research contexts and from perspectives of cultural comparison.Further discussion would also benefit from linking missionaries' mental health development to the discussion of psychological acculturation and adaptation before, during, and after the mission assignment.Future empirical studies could explore the link between intercultural learning and incidences of mental health issues.

Acculturation of Missionaries and Their Families during Missionary Postings Overseas
Despite the huge number of active missionaries throughout the world, only limited attention has been given to the quality of missionary activities and the personal attitudes and experiences of missionaries necessary for the successful completion of a mission posting in empirical investigations.Navara and James (2002) carried out a study on the effects of acculturation of missionaries who have spent a longer period in Nepal, investigated through a questionnaire (in a post-test design with a control group).The control group consists of two heterogeneous samples.The staff posted abroad were mainly from Australia, Great Britain, Canada, New Zealand, the USA, and Western Europe.They were aged between 25 and 71 and lived in Nepal for an average of five years.A total of 100 missionaries and 67 overseas workers from other professions and areas of activity were questioned.Both research groups received the same questionnaire, which comprised seven criteria: adaptation to the host culture, satisfaction with life in the host culture, feelings of self-worth, social support, problems, perceived acculturation stress, and convictions of control.This investigation aimed to compare the missionary personnel concerning their degree of adaptation and their chosen coping and/or managing strategies with other non-missionary workers posted overseas (including, among others, non-religious nongovernmental institutions, embassy staff, and employees of commercial enterprises).All research partners encountered at least similar situations and living conditions during their residence in Nepal, including difficult climatic conditions, unreliable water supplies, limited use of electricity, health risks, and the execution of similar activities for between two and 10 years with no possibility of change or leaving the program.
The primary areas of investigation were two hypothetical contexts.First, it was assumed that missionaries could adapt to a greater degree than the control group because of their more intensive engagement with the host culture (measured by satisfaction with their activities and general living conditions).Second, it was assumed that feelings of self-worth and social support would represent moderating factors for dealing with acculturation stress and helping to simplify cultural adaptation, for example.Both hypotheses were related to the assumption that due to the missionaries' generally positive attitudes and personal religious convictions about the rightness of their activities, a high level of satisfaction, active stress management, and a stronger belief in the social value of their achievements might be presumed.Still, it was impossible to validate the two hypothetical contexts: first, there was a negative correlation between stress variables (e.g., problems and perception of stress) and the effects of the overseas posting (satisfaction with activities and general living conditions as well as cultural adaptation).Second, a predominantly negative correlation existing between stress and moderating variables (social support, self-confidence, and conviction of being in control) was reported.Additionally, during their posting, the missionaries showed a significantly lower level of satisfaction and cultural adaptation than in the case of other overseas staff, which could be traced back to different causes: the more intensive and direct contact with members of the host culture, as much as with their lower social status (e.g., lower salary, a lower standard of living), disappointed expectations, and the feeling that they experienced less social support in their milieu (life in small villages and hardly any contact with other members of the same nationality) than other overseas employees with a similar cultural background.This result indicates that the two groups of overseas employees chose different strategies concerning their cultural adaptation.Navara and James (2005) concluded based on these results that missionaries who experience stress may not seek support from others, or perceive the stress of living in a foreign placement due to the lack of social support-i.e., the more the missionaries' perception of stress increases, the more strongly they feel "left in the lurch".This assumes that confirmation of self-worth may be achieved through, e.g., meditation, pastoral care, and strength of belief.

Acculturation Stress: Identification of Stress Factors among Missionaries
The analysis and identification of specific stressors directly associated with missionary activity have likewise been the subject of various studies for which general psychological stress theories provide a basis.Stress is generally described as a state "when people perceive the challenges of a situation as difficult and as a strain on their resources and a threat to their well-being" (Jonas et al. 2002, p. 604, transl. by author).Stress influences the ability to function socially and the physical and psychological health of an individual (Jonas et al. 2002).It has been shown that sources of stress are directly associated with missionaries' professional field of activity (Gish 1983), and social rejection and frustration can be interpreted as reactions to feelings of stress (Taylor and Malony 1983).
The identification of potential sources of stress and/or stressors in the group of missionaries is central to, among others, the study by Gish (1983), which documents a survey of 547 missionaries from various missionary societies (including the Brethren Church, Mennonites, and Christian Academies) in various postings and countries (primarily South-East Asia).In the questionnaire, these terms were employed as moderating factors (independent variables): location of posting, age, gender, family status, nationality, length of posting, nature of the activity, and working hours per week.Following evaluation by the Likert scale, five chief sources of stress were identified:

•
Confrontation: Women were subject to more marked stress in social conflicts, and stress appeared more strongly in a limited milieu.

•
Intercultural communication: Direct communication with members of the host culture was experienced as stressful.
• Maintaining social relations: More than half the missionaries cited this as a source of stress, especially when they had to negotiate arrangements for help and support, e.g., in interdenominational groups.

•
Excessive workloads: Reduce stress and maintain productivity as excessive workloads can negatively affect the quality of work, personal life, and health.

•
Organising the workflow: Defining goals, prioritising tasks, and utilising tools and resources for efficient time and self-management is crucial in mission practices.
Gish proceeds from the assumption that most of these sources of stress-if they are made the subject of intercultural preparations for the overseas posting-can be reduced in intensity, especially when practical training is provided in conflict resolution and general management skills.The results of the study by Gish were later replicated by Carter (1999) and confirmed by higher statistical significance.Additionally, it could be shown that increased doubts in the family and the relationship between spouses were a greater source of stress among women and less among men.

Reintegration of Missionaries and Their Families
The re-acculturation or reintegration ("re-entry") of missionaries and their families into their home culture was investigated in addition to their adaptation to foreign cultures.As with other personnel groups posted overseas, the reintegration of missionaries does not represent an established field of research (e.g., Rings and Rasinger 2020; Ward et al. 2001).Detailed descriptions of the challenges in the reintegration of the specific target group of missionaries are absent from previous studies.
Like "cultural adaptation" in foreign countries, "reintegration" has been described in various phased models, which differ regarding the intensity, differentiation, and length of the process of adaptation (Adler 1981;Austin 1986).In the study by Moore et al. (1987), 255 Missionaries from the North American mainline United Church of Christ (UCC) who had spent at least a year in the USA on home leave between 1971 and 1981 were questioned using a 12-page questionnaire, incorporating the Moore-Austin Reverse Culture Shock Scale developed by the authors, about their preparation for missionary activity, their experiences overseas, and experiences of reintegration.However, the findings of these studies lack validity and reliability; no standardised research tools were implemented.The significant correlations are not precisely explained, and the experiences collected based on several mission postings and return scenarios were not properly differentiated.The sole conclusion which can be drawn is that "re-entry culture shock" is influenced by various factors and/or variables such as family status, state of health, and spiritual adaptation abroad and on returning.
Additionally, specific challenges arise when these missionaries return home; children who considered their residence in their parent's host country as their own country and their "home" generally could not relate to their parents' conversations about the "old" country.Missionaries' children-like the Third Culture Kids in general-mostly do not possess the citizenship of their home country (or the parents' host country) but are socialised in a different culture from that of their parents and have another, possibly "hybrid" or "combined" cultural identity (Bhabba 1994) than their parents.The results of the questionnaire study by Roth (2003) reflect an ambivalent image of the situation; while the overwhelming majority of the missionaries' children noted they had problems getting used to their home country, an equally large proportion reported that their experiences in a pluralistic and multicultural context such as that of a Christian mission had made it easier to do so.In the long term, dealings with the authorities, anger, frustration, and parents' loneliness frequently caused problems.According to Roth (2003), reintegration may be shaped by a framework of various conditions, e.g., by various opportunities for preparation, consisting of information and interactive content which includes general problems of reintegration relating to the mission (e.g., friendships with others of the same age of other cultural origins than their parents, learning various languages, awareness of different moral concepts) and practical everyday ones directly related to family, leisure, and school (e.g., information about financial assistance, the availability of official opportunities, medical provision, the educational system, professional training, and continuing education, study, etc.).
Other studies that used consensual qualitative research methods suggest that especially psychological constructs associated not only with resilience, such as flexibility, high expectancy, and self-determination, but also with factors such as denial using minimisation, mental health, social support, reintegration, and personal spiritual connection with God are of paramount importance to missionaries' re-entry to their country of origin (Selby et al. 2009).Re-entrants also reported experiences in another study of multiple losses including loss of identity which may be associated with personal/relational identity gaps and depersonalization/dehumanization: "[R]esilient participants have been shown to have good mental health, whereas the fragile participants had poorer mental health with lower mental health indices for depression.The results from this study also suggest that fewer resilient participants described depersonalization/dehumanization than the fragile participants which may have strengthened their sense of coherence especially in meaningfulness, while more fragile participants described depersonalization/dehumanization which may have decreased their sense of coherence" (Selby et al. 2011(Selby et al. , p. 1018)).

Discussion and Direction of Future Research
This study summarised the findings of a systematic review of the literature about missionary's acculturation and learning in the mission field through the lens of intercultural communication and competence.The review applied a transdisciplinary approach and included research from anthropological, cultural, historical, psychological, and sociological perspectives.As has been shown, the acculturation of missionaries and their families during their postings overseas is characterised by stressful experiences in the adaptation to the new social and cultural environment and during the reintegration at home.Several criteria have a lasting effect on the missionary's effectiveness and well-being during and after the assignment, such as critical life events, premature termination of the posting, and upcoming retirements.Other studies discovered that certain personality traits and an ability to cope with psychological pressure in stressful situations would help to predict the success of a mission assignment such as because of their spiritual and organisational commitment as well as individual expectations.Eventually, the review brought to light that certain role orientations of missionary's wives, the psychological well-being within the marriage, and the partnership of the couple posted overseas has a positive effect on the success of the mission.The literature review concluded with an overview of the emancipatory role of women in missionary work.What follows is a discussion of the strengths and weaknesses of the research, including recommendations for future research directions.
Despite the mentioned findings and advancements in the present study, the merits and limitations of the research need to be discussed.First, it is predictable that missionaries will always give a relatively high score on psychological tests when answering questions about their intrinsic religious motivation, as no doubt generally exists in their case that the mission represents the right occupational area for them.Rather, the various individual (normative) strategies and approaches and/or personal religious convictions, the success of the mission from missionaries' perspectives, and the challenges facing missionaries' families should stand in the foreground of empirical studies and be correspondingly explored (cf., Navara andJames 2002, 2005;Stringham 1993).
Second, a desideratum can generally be found in the methodological strategies usually followed in the empirical studies cited; great interest exists in the "predicators, moderators and results of the acculturation process" (Weidemann 2007, p. 493, transl.by author) but far too rarely do studies focus on the subjective and personal process of change and individual perspectives on subjective experience within the process of cultural transfer.Future studies have the immediate task of defining the connections examined and the predicators of the acculturation process more precisely and introducing new methodical and methodological research perspectives.Additionally, the processes of transformation of social and individual identities could be investigated in long-term studies.To describe concrete factors influencing the process of adjustment of missionaries in more precise terms, a process of exclusion (recursive qualitative research) could be used in measuring and defining variables.
Third, few efforts have hitherto been made to clarify the question of how the results and insights gained from research into the group under examination may be applied to others.The results of empirical investigations and research perspectives are not yet sufficient for an area-specific theory of acculturation and intercultural learning among missionaries.The requirements and the research program's approach towards differentiation and refinement of typical acculturation and reintegration strategies and criteria for the diagnosis of aptitude for the context of the mission have been only partially registered; these adjustment strategies by missionaries lie within a possible spectrum from an "entering into" to a "turning away from" or "leaving" the host culture.Adjustment occurs between the avoidance of conflict and the striving for consonance and/or the avoidance of dissonance, between old and new everyday practices and individual views of life, and collective requirements (Berry 2006).The question remains open of how the relationship between cultural adjustment and missionaries' achievements is constituted and is evaluated from the viewpoint of missionaries in their various respective contexts (Parker and McEvoy 1993).
Fourth, due to the selection of publications and the design of this systematic literature review, the results are subject to certain restrictions.The findings of the literature analysis do not claim to establish generalisations.Conclusions and interpretations of mentioned analyses can be only vaguely and tentatively formulated.Most studies are "exploratory" and predominantly identify and answer questions of an empirical quality and not directly to generate precise theoretical concepts.Therefore, every interpretation must be constantly subject to careful examination and replicated in later studies.The review on missionary acculturation highlights a certain socio-cultural bias in cross-cultural mission studies.Thus, the research presented here is likely to have limited applicability to missionaries, for example, from non-Western countries, and generalisations are only possible about the specific populations of missionaries.Future research must also reflect that any "community and experiential learning can unintentionally reinforce culturally shaped theological convictions, social conventions, and ethical practices, especially when groups engaging in missionary education are essentially homogeneous in terms of their religious and socio-ethical emphases" (Herppich 2014, p. 217).
Lastly, the critical observation is regularly made that in most models, an essentialist concept of culture (individuals as representatives of a culture) is employed.The typical ideal requirement frequently expressed for a linking of current models of acculturation and learning to exist theoretical concepts, as suggested by Ward (2004), for example, can be achieved from two perspectives.On the one hand, general psychological theories and theories about the personality or theories about learning and stress may be systematically and explicitly adapted to the requirements of contacts between cultures, refined and differentiated, as done with theories from other scientific disciplines.On the other hand, the results of empirical studies in specific socio-cultural contexts may also contribute to differentiation and wider application of the results of earlier research.

Conclusions
In conclusion, this comprehensive literature review highlights the wide range of empirical and systematic studies published between 1954 and 2010 on the adaptation and acculturation of missionaries and their families to new social and cultural environments, as well as their reintegration upon returning home.The review identifies a number of stressors faced by missionaries and personality traits and coping mechanisms that can affect the effectiveness of a mission assignment.The review sheds light on the role orientations of missionary wives, their psychological well-being within marriage, and the broader role of women in missions.These findings provide a valuable foundation for future research and critical analyses, as well as informing the development of cross-cultural communication and competence in missionary work.