Emerging adulthood and early adulthood

Emerging adulthood refers to a phase of the life span between late adolescence and early adulthood, as proposed by Jeffrey Arnett in a 2000 article from the "American Psychologist". It primarily describes people living in developed countries, but it is also experienced by young people in urban wealthy families in the Global South. The term describes young adults who do not have children, do not live in their own home, and/or do not have sufficient income to become fully independent. Arnett suggests emerging adulthood is the distinct period between 18 and 25 years of age where adolescents become more independent and explore various life possibilities. Arnett argues that this developmental period can be isolated from adolescence and young adulthood, although the distinction between adolescence and young adulthood has remained largely unclear over the last several decades. Emerging adulthood's state as a new demographic is continuously changing, although some believe that twenty-somethings have always struggled with "identity exploration, instability, self-focus, and feeling in-between." Arnett referred to emerging adulthood as a "roleless role" because emerging adults engage in a wide variety of activities, but are not constrained by any sort of "role requirements." The developmental theory is highly controversial within the developmental field, and developmental psychologists argue over the legitimacy of Arnett's theories and methods.
Distinction from young adulthood and adolescence.
Terminology.
Coined by psychology professor Jeffrey Arnett, emerging adulthood has been known variously as "transition age youth," "delayed adulthood," "extended adolescence," "youthhood," "adultolescence," and "the twixter years." Of the various terms, "emerging adulthood" has become popular among sociologists, psychologists, and government agencies as a way to describe this period of life in between adolescence and young adulthood.
Compared to other terms that have been used, which give the impression that this stage is just a "last hurrah" of adolescence, "emerging adulthood" recognizes the uniqueness of this period of life. Currently, it is appropriate to define adolescence as the period spanning ages 12 to 18. In the United States, young people in this age group typically live at home with their parents, are undergoing pubertal changes, attend middle schools and high schools, and are involved in a "school-based peer culture." All of these characteristics are no longer normative after the age of 18. It is, therefore, considered inappropriate to call young adults "adolescents" or "late adolescents". Furthermore, in the United States, the age of 18 is the age at which people are able to legally vote and citizens are granted full rights upon turning 21 years of age.
According to Arnett, the term "young adulthood" suggests that adulthood has already been reached, however most people in the emerging adulthood stage no longer consider themselves adolescents, but do not see themselves entirely as adults either. In the past, milestones such as finishing secondary school, finding a job, and marrying clearly marked the entrance to adulthood. However, in modern, post-industrialized nations, as positions requiring a college degree have become more common and the average age of marriage has become older, the length of time between leaving adolescence and reaching these milestones has been extended, delaying the age at which many young people fully enter adulthood. If the years 18–25 are classified as "young adulthood", Arnett believes it is then difficult to find an appropriate term for the thirties. Emerging adults are still in the process of obtaining an education, are unmarried, and are childless. By age thirty, most of these individuals do see themselves as adults, based on the belief that they have more fully formed "individualistic qualities of character" such as self-responsibility, financial independence, and independence in decision-making. Arnett suggests that many of the individualistic characteristics associated with adult status correlate to, but are not dependent upon, the role responsibilities associated with a career, marriage, and/or parenthood.
Exploration of identity.
One of the most important features of emerging adulthood is that this age period allows for exploration in love, work, and worldviews, also known as the volitional years. The process of identity formation emerges in adolescence but mostly takes place in emerging adulthood. This stage in life allows young individuals to develop characteristics that will help them become self-sufficient, engage in mature committed relationships, and obtain a level of education and training that will set them up for work during the adult years. Regarding love, although adolescents in the United States usually begin dating between ages 12 and 14, they usually view this dating as recreational. It is not until emerging adulthood that identity formation in love becomes more serious. Emerging adults are considering their own developing identities as a reference point for a lifetime relationship partner, so they explore romantically and sexually as there is less parental control. While in the United States during adolescence, dating usually occurs in groups and in situations such as parties and dances and some shared sexual experiences. In emerging adulthood, relationships last longer and often include more permanent sexual relations as well as cohabitation.
As far as work, the majority of working adolescents in the United States tend to see their jobs as a way to make money for recreational activities rather than preparing them for a future career. In contrast, 18- to 25-year-olds in emerging adulthood view their jobs as a way to obtain the knowledge and skills that will prepare them for their future adulthood careers. Because emerging adults have the possibility of having numerous work experiences, they are able to figure out what type of work they are good at as well as find what type of work they want to pursue for the rest of their lives. Changing worldviews is a characteristic of cognitive development during emerging adulthood.
People in emerging adulthood that choose to attend college often begin college or university with the worldview they were raised with and learned in childhood and adolescence. However, emerging adults who have attended college or university have been exposed to and have considered different worldviews, and eventually commit to a worldview that is distinct from the worldview with which they were raised by the end of their college or university career.
Opposed to all of the stresses that normally accompany this time of life, a defining quality that is constant amid most emerging adults is an optimism about the future. Americans between the ages of 18 and 24 were asked if they thought that their lives would be better or worse than their parents 92% from this survey stated that they believed that their lives would be as good or better than their parents. Though reasons for optimism differ from socioeconomic status (SES) and ethnical backgrounds generally emerging adults believe that they will have a happier family, or that they will have a higher paying job. Though for emerging adults it is not just about the idea of having a better job or more income that is the source of their optimism, it has also been traced back heavily to the belief that they will have a better balance between work and home then their parents have. This optimism is usually traced back to young adults not having as much experience with failure as their older counterparts.
Subjective difference.
When Americans between the ages of 18 and 25 are asked whether they believe they have reached adulthood, most do not answer with a "no" or a "yes", but answer with "In some respects yes, in some respects no." It is clear from this ambiguity that most emerging adults in the United States feel they have completed adolescence, but not yet entered adulthood.
A number of studies have shown that regarding people in their late teens and early twenties in the United States, demographic qualities such as completing their education, finding a career, marrying, and becoming parents are not the criteria used in determining whether they have reached adulthood. Rather, the criteria that determine whether adulthood has been reached are certain characteristics, such as being able to make independent decisions and taking responsibility for one's self. In America, these qualities are usually experienced in the mid to late twenties, thus confirming that emerging adulthood is distinct subjectively.
Why emerging adulthood is distinct demographically.
Emerging adulthood is the sole age period where there is nothing that is demographically consistent. At this time, over 95% of adolescents over the age of 20 in the United States live at home with at least one parent. Additionally, 98% are not married, under 10% have become parents, and more than 95% attend school. Similarly, people in their thirties are also demographically normative: 75% are married, 75% are parents, and under 10% attend school. Residential status and school attendance are two reasons that the period of emerging adulthood is incredibly distinct demographically. Regarding residential status, emerging adults in the United States have very diverse living situations. About one third of emerging adults attend college and spend a few years living independently while partially relying on adults.
Contrastingly, 40% of emerging adults do not attend college but live independently and work full-time. Finally, around two-thirds of emerging adults in the United States cohabitate with a romantic partner. Regarding school attendance, emerging adults are also extremely diverse in their educational paths (Arnett, 2000, p. 470-471). Over 60% of emerging adults in the United States enter college or university the year after they graduate from high school. However, the years that follow college are extremely diverse – only about 32% of 25- to 29-year-olds have finished four or more years of college.
This is because higher education is usually pursued non-continuously, where some pursue education while they also work, and some do not attend school for periods of time. Further contributing to the variance, about one third of emerging adults with bachelor's degrees pursue a postgraduate education within a year of earning their bachelor's degree. Because there is so much demographic instability, especially in residential status and school attendance, it is clear that emerging adulthood is a distinct entity based on its demographically non-normative qualities, at least in the United States. Some emerging adults end up moving back home after college graduation, which tests the demographic of dependency. During college, they may be completely independent, but that could quickly change afterwards when they are trying to find a full-time job with little direction as to where to start their career. Only after self-efficiency has been reached and after a long period of freedom has experienced, that is when emerging adults will be ready to become adults and take on the full responsibility.
History.
In the early 1960s, the average age that young adults were marrying was 20.3 years old for women and 22.8 years old for men, which included a child or expecting a child and/or finishing up education. Young mothers were settling into their full-time mothers’ roles, whereas fathers/husbands had established themselves into their working careers. In the 1970s the average age for childbirth started to increase, by 2010 it rose to 26 years for women and 28 for men.  There were revolutions that changed everything people knew in the 1960s and 70s, contributing to the existence of the emerging adulthood stages of life.
The Technology Revolution: This revolution transformed the United States’ (and other industrializing economies) from manufacturing economies to knowledge and skill-based economies. After computers became widespread throughout homes and workplaces, more education was required for employment. This prompted younger adults to spend more and more time in school, rather than working full time or starting families. These are both characteristics generally associated with "full-on" adulthood.  
The Sexual Revolution: The sexual revolution, which began in the early 1960s, led to emerging adulthood because young adults began having sexual relations before marriage or having children. This was, in part, due to the development of more effective methods of contraception. For example, in 1964, birth control became another option for young adults. This resulted in postponing marriage and parenthood age back a few years, changing the early and mid- twenties from a time of married relationships to a time of non-committed sexual relationships. Younger adults were no longer leaving home to get married. Marriage became less and less of a standard or "pre-requisite" of adulthood. Because of this, this stage of life was no longer characterized by the responsibilities and organization of marriage, leaving younger adults in qualitatively different relationships than before.  
The Women's Movement: The Women's movement also contributed to the development of emerging adulthood. Before this movement, their sole purpose was to find a husband and bare children, becoming full-time housewives. Soon after, women began to seek options for careers and education that were uncommon in the 1960s. Because of this, more women spend their emerging adulthood (approximately ages 20–29) years pursuing careers and higher education rather than settling down and starting families. This delay in marriage age developed the emerging adult phase of life because many people at this age were exploring and pursuing different paths than predecessors.  
The Youth Movement: This movement represented a shift in the cultural attitudes and perceptions of adulthood. Previous to this movement in the 1960s and 1970s, many young people aspired to grow up and become adults who were considered wise, in control, and independent. This movement changed perceptions of adulthood to be less favorable than those of youth. Music and phrases reflected the growing movement to celebrate youth and renounce aging. For example, phrases like “I want to be forever young” and “never trust adults” became increasingly common, and youth began to prevail over wisdom in terms of popularity. Because of this, young adults postponed adulthood and prolonged their youth into their twenties by living independently of conditions and characteristics associated with adulthood. The delay of adulthood and popularization of remaining young brought about by this revolution led to the development of emerging adulthood.
Physiological development.
Biological changes.
Emerging adulthood and adolescence differ significantly with regard to puberty and hormonal development. While there is considerable overlap between the onset of puberty and the developmental stage referred to as adolescence, there are considerably fewer hormonal and physical changes taking place in individuals between the ages of 18–25. Emerging adults have reached a stage of full hormonal maturity and are fully, physically equipped for sexual reproduction.
Emerging adulthood is usually thought of as a time of peak physical health and performance as individuals are usually less susceptible to disease and more physically agile during this period than later stages of adulthood. However, emerging adults are generally more likely to contract sexually transmitted infections, as well as to adopt unhealthy behavioral patterns and lifestyle choices.
Personality organization will have an increased instability during this stage and after will have an increased stability. This will help us understand personality development through the years. Social dominance, emotional stability, and conscientiousness increased more in this stage and during this time social vitality decreased. This is compared to changes in later adulthood. Emerging adults develop the ability to move away from spontaneous behavior to more stability and better self-control. This self-control that develops during this stage includes life planning, being reflective, intentional, and more cautious. Emerging adults will trust in themselves to create strategies that will completely guide them in their lives. They will experience a rise in their sense of their successes and social power, and will reflect what they have gained from meeting challenges such as the school to work challenge.
Cognitive development.
While many people believe that the brains of emerging adults are fully developed, they are in fact still developing into their adult forms. Many connections within the brain are strengthened and those that are unused are pruned away. Several brain structures develop that allow for greater processing of emotions and social information. Areas of the brain used for planning and for processing risk and rewards also undergo important developments during this stage. These developments in brain structure and the resulting implications are one factor that leads emerging adults to be considered more mature than adolescents. This is due to the fact that they make fewer impulsive decisions and rely more on planning and evaluating of situations. Even though emerging adults have not lived as long as older adults they have better solutions to problems than the older adults. This shows that practical intelligence is prominent during emerging adulthood.
While brain structures continue to develop during emerging adulthood, the cognition of emerging adults is an area that receives the majority of attention. Arnett explains, "Emerging adulthood is a critical stage for the emergence of complex forms of thinking required in complex societies." Crucial changes take place in their sense of self and capacity for self-reflection. At this stage, emerging adults often decide on a particular worldview and are able to recognize that other perspectives exist and are valid as well. While cognition generally becomes more complex, education level plays an important role in this development. Not all emerging adults reach the same advanced level in cognition because of the variety of education received during this age period.
Abnormal development.
Much research has been directed at studying the onset of lifetime DSM disorders to dispel the common thought that most disorders begin earlier in life. Because of this reasoning, many people that show signs of disorders do not seek help due to its stigmatization. The research shows that those with various disorders will not feel symptoms until emerging adulthood. Kessler and Merikangas reported that "50% of emerging adults between the ages of 18 and 25 experience at least one psychiatric disorder." Not only is the emergence of various disorders prevalent in emerging adulthood, but the chance of developing a disorder drastically decreases at age 28.
Seventy-five percent of any lifetime DSM-IV anxiety, mood, impulse-control and substance abuse disorder begins before age 24. Most onsets at this age will not be, or become, comorbid. The median onset interquartile range of substance use disorders is 18–27, while the median onset age is 20. The median onset age of mood disorders is 25.
Even disorders that begin earlier, like schizophrenia spectrum diagnoses, can reveal themselves within the age range of emerging adulthood. Often, patients will not seek help until several years of symptoms have passed, if at all. For example, those diagnosed with social anxiety disorder will rarely seek treatment until age 27 or later. Typically, symptoms of more severe disorders, such as major depression, begin at age 25 as well. Depression symptoms are higher in the 20's compared to the older generation with the exclusion of the 80's. The negative effect is also higher in the 20's but it will hit a peak then the negative effect will decrease.
With the exception of some phobias, symptoms of many disorders begin to appear and are diagnosable during emerging adulthood. Major efforts have been taken to educate the public and influence those with symptoms to seek treatment past adolescence. There is minimal but intriguing evidence that those who attend college appear to have less of a chance of showing symptoms of DSM-IV disorders. In one study, "they were significantly less likely to have a diagnosis of drug use disorder or nicotine dependence". In addition, "bipolar disorder was less common in individuals attending college". However, other research reports that chance of alcohol abuse and addiction is increased with college student status.
Relationships.
Parent-child relationship.
Emerging adulthood is characterized by a reevaluation of the parent-child relationship, primarily in regard to autonomy. As a child switches from the role of a dependent to the role of a fellow adult, the family dynamic changes significantly. At this stage, it is important that parents acknowledge and accept their child's status as an adult. This process may include gestures such as allowing increased amounts of privacy and extending trust. Granting this recognition assists the increasingly independent offspring in forming a strong sense of identity and exploration at a time when it is most crucial.
There is varied evidence regarding the continuity of emerging adults' relationships with parents, although most of the research supports the fact that there is moderate stability. A parent-child relationship of higher quality often results in greater affection and contact in emerging adulthood. Attachment styles tend to remain stable from infancy to adulthood. An initial secure attachment assists in healthy separation from parents while still retaining intimacy, resulting in adaptive psychological function. Changes in attachment are often associated with negative life events, as described below.
Divorce and remarriage of parents often result in a weaker parent-child relationship, even if no adverse effects were apparent during childhood. When parental divorce occurs in early adulthood, it has a strong, negative impact on the child's relationship with their father.
However, if parents and children maintain a good relationship throughout the divorce process, it could act as a buffer and reduce the negative effects of the experience. A positive parent-child relationship after parental divorce may also be facilitated by the child's understanding of divorce. Understanding the complexity of the situation and not dwelling on the negative aspects may actually assist a young adult's adjustment, as well as their success in their own romantic relationships.
Despite the increasing need for autonomy that emerging adults experience, there is also a continuing need for support from parents, although this need is often different and less dependent than that of children and earlier adolescents. Many people over the age of 18 still require financial support in order to further their education and career, despite an otherwise independent lifestyle. Furthermore, emotional support remains important during this transition period. Parental engagement with low marital conflict results in better adjustment for college students. This balance of autonomy and dependency may seem contradictory, but relinquishing control while providing necessary support may strengthen the bond between parents and offspring and may even provide space for children to be viewed as sources of support.
Parental support may come in the form of co-residence, which has varied effects on an emerging adult's adjustment. The proportion of young adults living with their parents has steadily increased in recent years, largely due to financial strain, difficulty finding employment, and the necessity of higher education in the job field. The economic benefit of a period of co-residence may assist an emerging adult in exploration of career options. In households with lower socioeconomic status, this arrangement may have the added benefit of the young adult providing support for the family, both financial and otherwise.
Co-residence can also have negative effects on an emerging adult's adjustment and autonomy. This may hinder parents' ability to acknowledge their child as an adult, while home-leaving promotes psychological growth and satisfying adult-to-adult relationships with parents characterized by less confrontation. Living in physically separate households can help both a young adult and a parent acknowledge the changing nature of their relationship.
Romantic relationships.
Serious romantic relationships often begin to occur in adulthood. Data on participants in a German longitudinal study indicated that 43% of middle adolescents and 47% of late adolescents reported romantic relationships compared to 63% in emerging adulthood. Emerging adulthood relationships carried on for 21.3 months compared to adolescence, which is 5.1 and 11.8 months. Montgomery and Sorell (1994) did a study on romantic love and it reported that unmarried emerging adults would be more dominating, clingy, possessive, and dependent compared to young and married couples who have an altruistic selfless love. Emerging adults had less satisfaction in their relationships. Emerging adults also tended to cohabit with their romantic partners, which helped with their finances and housing situations. Cohabitation usually led to marriage. Data shows that 60% of American emerging adults will live with a partner, and over half of cohabitating relationships result in marriage.
Sexual relationships.
There are a wide variety of factors that influence sexual relationships during emerging adulthood; this includes beliefs about certain sexual behaviors and marriage. For example, among emerging adults in the United States, it is common for oral sex to not be considered "real sex". In the 1950s and 1960s, about 75% of people between the ages of 20–24 engaged in premarital sex. Today, that number is 90%. Unintended pregnancy and sexually transmitted infections and diseases (STIs/STDs) are a central issue. As individuals move through emerging adulthood, they are more likely to engage in monogamous sexual relationships and practice safe sex.
Across most OECD (Organization for Economic Co-operation and Development) countries, marriage rates are falling, the age at first marriage is rising, and cohabitation among unmarried couples is increasing. The Western European marriage pattern has traditionally been characterized by marriage in the mid twenties, especially for women, with a generally small age difference between the spouses, a significant proportion of women who remain unmarried, and the establishment of a neolocal household after the couple has married.
Housing affordability has been linked to home ownership rates, and demographic researchers have argued for a link between the rising age at first marriage and the rising age of first home ownership.
Friend Relationships.
Friendships are a resource that help emerging adults help master this developmental stage of tasks. During emerging adulthood friendships sometimes will be more important than your family relationships. Shulman (1975) found that when emerging adults (18-30) were asked who was in their personal networks 41% were more likely to not put down friends instead of family members. Emerging adults have reported that they have less positive feelings with their siblings, but have positive feelings with their friends. There was a study done on single emerging adults, that reported their most preferred companions were friends, especially if the emerging adult has no partner and no longer fully relies on their parents.
Culture.
Demographers distinguish between developing countries, which constitute more than 80% of the world's population, and the economically advanced, industrialized nations that form the Organization for Economic Co-Operation and Development (OECD). This includes countries and regions like the United States, Canada, Western Europe, Japan, South Korea, and Australia, all of which have significantly higher median incomes and educational attainment and significantly lower rates of illness, disease, and early death.
The theory of emerging adulthood is specifically applicable to cultures within these OECD nations, and as a stage of development has only emerged over the past half century. It is specific to "certain cultural-demographic conditions, specifically widespread education and training beyond secondary school and entry into marriage and parenthood in the early or late thirties or beyond".
Furthermore, emerging adulthood occurs only within societies that allow for occupational shifts, with emerging adults often experiencing frequent job changes before settling on a particular job by the age of 30. Arnett also argues that emerging adulthood happens in cultures that allow for a period of time between adolescence and marriage, the marker of adulthood. Such marital and occupational instability found among emerging adults can be attributed to the strong sense of individualization found in cultures that allow for this stage of development; in individualized cultures, traditional familial and institutional constraints have become less pronounced than in previous times or in unindustrialized/developing cultures, allowing for more personal freedom in life decisions. However, emerging adulthood even occurs in industrialized nations that do not value individualization, as is the case in some Asian countries discussed below.
Up until the latter portion of the 20th century in OECD countries, and contemporarily in developing countries around the world, young people made the transition from adolescence to young adulthood around or by the age of 22, when they settled into long-lasting, obligation-filled familial and occupational roles. Therefore, in societies where this trend still prevails, emerging adulthood does not exist as a widespread stage of development.
Among OECD countries, there is a general "one size fits all" model in regards to emerging adulthood, having all undergone the same demographic changes that resulted in this new stage of development between adolescence and young adulthood. However, the shape emerging adulthood takes can even vary between different OECD countries, and researchers have only recently begun exploring such cross-national differences. For instance, researchers have determined that Europe is the area where emerging adulthood lasts the longest, with high levels of government assistance and median marriage ages nearing 30, compared to the U.S. where the median marriage age is 27.
Emerging adult communities in East Asia may be most dissimilar from their European and American counterparts, for while they share the benefits of affluent societies with strong education and welfare systems, they do not share as strong a sense of individualization. Historically and currently, East Asian cultures have emphasized collectivism more so than those in the West. For instance, while Asian emerging adults similarly engage in individualistic identity exploration and personal development, they do so within more constrictive boundaries set by familial obligation. For example, European and American emerging adults consistently list financial independence as a key marker of adulthood, while Asian emerging adults consistently list capable of supporting parents financially as a marker with equal weight. Some Asian emerging adults feel that getting married is a step only after school is finished and parents are cared for. Furthermore, while casual dating and premarital sex has become normative in the West, in Asia parents still discourage such practices, where they remain "rare and forbidden". In fact, about 75% of emerging adults in the U.S. and Europe report having had premarital sexual relations by the age of 20, whereas less than 20% in Japan and South Korea reported the same.
While emerging adulthood exemplars are found mainly within the middle and upper classes of OECD countries, the stage of development still seems to occur across classes, with the main difference between different ones being length—on average, young people in lower social classes tend to enter adulthood two years before those in upper classes.
While emerging adulthood occurs on a wide scale only in OECD countries, developing countries may also exhibit similar phenomena in certain population subgroups. In contrast to those in poor or rural parts of developing nations, who have no emerging adulthood and sometimes no adolescence due to comparatively early entry into marriage and adult-like work, young people in wealthier urban classes have begun to enter stages of development that resemble emerging adulthood, and the amount to do so is rising. Such individuals may develop a bicultural or hybrid identity, with part of themselves identifying with local culture and another part participating in the professional culture of the global economy. One finds examples of such a situation among the middle class young people in India, who lead the globalized economic sector while still, for the most part, preferring to have arranged marriages and taking care of their parents in old age. While it is more common for emerging adulthood to occur in OECD countries, it is not always true that all young people of those societies have the opportunity to experience these years of change and exploration.
Media.
Emerging adulthood is not just an idea being talked about by psychologists, the media has propagated the concept as well. Hollywood has produced multiple movies where the main conflict seems to be a "grown" adult's reluctance to actually "grow" up and take on responsibility. "Failure to Launch" and "Step Brothers" are extreme examples of this concept. While most takes on emerging adulthood (and the problems that it can cause) are shown in a light-humored attempt to poke fun at the idea, a few films have taken a more serious approach to the plight. "Adventureland", "Take Me Home Tonight", "Cyrus" and "Jeff, Who Lives at Home" are comedy-dramas that exhibit the plight of today's emerging adult. Television also is capitalizing on the concept of emerging adulthood with sitcoms such as "$h*! My Dad Says" and "Big Lake".
However, it is not just on television where society sees the world becoming aware of this trend. In spring 2010, "The New Yorker" magazine showcased a picture of a post-grad hanging his PhD on the wall of his bedroom as his parents stood in the doorway. People do not have to seek out these media sources to find documentation of the emerging adulthood phenomenon. News sources about the topic are abundant. Nationwide, it is being found that people entering their 20s are faced with multitudes of living problems creating problems that this age group has received a lot of attention for. The Occupy movement is an example of what has happened to the youth of today and exhibits the frustration of today's emerging adults. Other television shows and films showcasing emerging/early adulthood are "Girls", "How I Met Your Mother", and "Less Than Zero."
Criticism.
The concept of emerging adulthood has not been without its criticisms. Sociologists have pinpointed that it neglects class differences. While it might be true that middle class children in Western societies are spoiled for choice and can afford to postpone life decisions, there are other young people who have no choices at all, and stay in the parental home not because they want to, but because they cannot afford a life of their own: They experience a period of "arrested adulthood".
A more theoretical criticism comes from developmental psychologists, who regard all stage theories as outdated. They argue that development is a dynamic interactive process, which is different for every individual, because every individual has their own experiences. Inventing a stage that only describes (not explains) a time period in the life of a few individuals (mostly white, middle-class young people living in Western societies within this decade), and has nothing to say about people living in different conditions or different points in history is not a scientific approach.
Arnett has taken up some of these critical points in public discussion.