Peculiarities of Assertiveness Development and Ways of Socialization of Personality in Adolescence

: Adolescence is a crisis period of personality development marked by significant physiological and neuropsychological changes that affect the growth and relationships with others. The uneven maturation of the limbic system and prefrontal cortex structures, characteristic of adolescence, provokes a decrease in subjective control and self-regulation, increased impulsivity, and emotional instability. Qualitative and quantitative morphometric changes in the brain of adolescents can cause behavioral problems, impaired control and self-regulation, a sharp change in areas of cognitive interests, the inability to understand themselves and explain their actions. These features are a predictor of the successful socialization of adolescents. Socialization is seen as a process in which the adolescent acquires the skills necessary for his entire existence in society. Psychophysiological changes in his body determine the nature and characteristics of socialization, relationships with others, the nature of actions, and social contacts. An important feature that promotes the adaptive socialization of adolescents is assertiveness. Assertiveness as personal property of behavior primarily involves the development of confidence, determination, perseverance, self-esteem, empathy, communication skills. The formation of assertive behavior significantly increases the adaptation processes of adolescents, normalizes the emotional sphere, has a positive effect on socialization, and sets the vector of social success, self-actualization, and self-realization.


Introduction
The transformational processes taking place in the modern world set a specific pace of development of society and make particular demands on the individual, who must be integrated into society most adaptively and optimally way, i.e., to socialize successfully. Socialization involves the entry of an individual into the system of social relations, his acceptance of the norms and rules of society (Kesebir et al., 2010), as a result of which he learns specific patterns of behavior and values necessary for his successful life in this society (Smetana et al., 2015). The most significant in the process of socialization is adolescence, as a sensitive period of learning behavior, self-expression, and self-affirmation, the formation of their worldview and value system (Demchenko et al., 2021;Komogorova et al., 2021;Kosholap et al., 2021;Maksymchuk et al., 2020a;Maksymchuk et al., 2020b;Prots et al., 2021;Sitovskyi et al., 2019). However, during this unstable and turbulent period of life, numerous deviations in adolescents' behavior occur, which are accompanied by the intake of prohibited substances or constant fixation of attention on specific activities to develop intense emotions (Şengönül, 2018).
Socialization in adolescence is multifaceted and can be adaptive or maladaptive due to the peculiarities of morphofunctional maturation of the organism (Soenens & Vansteenkiste, 2020). The nervous system of the adolescent is unstable and is characterized by changes in vital organs and systems (Rivera et al., 2020). Transformations in the brain during adolescence are associated with various manifestations of risky behavior (Caravita et al., 2020). The most significant influence is shown by natural heterochronous processes of maturation of multiple brain sites, neurohumoral changes in DNS. With age, the ability to inhibit, plan and recognize emotions in adolescents linearly improves. Risky behaviors characteristic of early adolescence increase significantly in late adolescence (Mürner-Lavanchy et al., 2020;Kaess, 2020). Such behavior is undesirable for successful socialization and needs some correction.
That is why it is worth paying attention to the possible means that will contribute to the optimal socialization of adolescents in modern society. One such tool is the development of assertive behavior. Assertiveness as a personality trait and a way of interaction is an essential factor in the successful socialization of adolescents (Parmaksız & Kılıçarslan, 2020) because, on the one hand, the adolescent must be adaptable to the new sociocultural environment, on the other -be focused, confident, active and determined. In adolescents, the combination of such states is not always successful due to functional psychophysiological changes, imbalance of excitation and inhibition processes (Kim-Spoon et al., 2016), unformed volitional self-regulation of mental processes (Mürner-Lavanchy et al., 2020). Assertiveness is seen as a balance between passive and aggressive behavior, and being assertive means respecting thoughts, feelings, and beliefs (Nair, 2021). The meaning of the concept of "assertiveness" is revealed through such personal traits as constructiveness, purposefulness, self-confidence, responsibility, determination, independence, independence, neuropsychological stability.
However, developed assertiveness is the key to high self-esteem of adolescents, empathy, the ability to have spontaneous reactions and manage emotional states (emotional intelligence) (Simarmata, 2018), the ability to speak directly about their desires and needs, the ability to express their views using argumentation, to insist on one's own (Yuliani et al., 2020); possession of tactics to meet their own needs and interests without violating the rights of others.
Thus, the analysis of scientific sources showed a significant amount of research that reveals the features of psychophysiological development of adolescents, behavioral manifestations of their psycho-emotional processes, areas of socialization and integration. However, little attention is paid to the importance of developing confident, assertive behavior for successful socialization.

Neuropsychological features of development in adolescence
Adolescence is a critical period of personality development, during which there is a qualitative restructuring of the whole organism of the individual, accompanied by physical, hormonal, and psychophysiological changes. Most adolescents during this period undergo drastic changes in appearance and inner world. Physiological processes occurring in adolescents' bodies cause them to change the nature, methods, and types of response to the surrounding reality, style of behavior (Salter, 2012). The critical need is the need for self-expression, which at the same time cannot be fully satisfied due to the lack of a system of claims and confidence in their actions (Korem et al., 2012). According to hormonal theory, adolescents have sharp mood swings, increased interest in the opposite sex (Kelley, 2006;Kim-Spoon, 2016).
From the point of view of neuropsychology and the theory of functional asymmetry of the brain, a vital role in the regulation of physical activity is played by the prefrontal cortex (Casey et al., 2008), which provide planning and programming of actions, regulation of behavior according to environmental requirements, self-control, and self-expression. In adolescence, there is an improvement of the essential functions of the prefrontal cortex, which contributes to the differentiation of motives and actions, integration of objects and concepts, the ability to predict the consequences of their actions and adjust if necessary, self-regulation, volitional control (Harden et al., 2016).
Given that the formation of these functions lasts up to 18 years, in adolescents, they are not yet fully formed. Insufficient formation and imperfection of the prefrontal cortex provoke various problems in adolescents: distracted and unstable attention, poor control over impulses, hyperactive behavior, disorganized activity, decreased emotional intelligence, short-term memory problems, and constant social anxiety (Hassan et al., 2020). As a result, the period of adolescent development is characterized by an increase in the frequency of health-threatening behaviors, including experiments with drugs and alcohol (Kim-Spoon et al., 2016).
The role of the prefrontal brain in the synthesis of the whole system of stimuli and the creation of a plan of action is manifested not only in the actual signals but also in the formation of active, purposeful behavior. Therefore, adolescence as a transition period is marked by abrupt changes in the brain's emotional regulation and cognitive functions. As a result, adolescents think and act differently than adults and behave more impulsively and recklessly. Risk-taking and finding new experiences are the main signs of typical adolescent behavior. Adolescents are eager for new experiences so much that, for the most part, they do not take into account the future consequences of their actions. From the point of view of adaptability, this style of behavior has certain advantages. It contributes to the formation of independence, but at the same time, makes the adolescent more vulnerable to external negative environmental influences (Kelley et al., 2006).
As B. Casey rightly points out, "traditional neurobiological and cognitive explanations for adolescent behavior have failed to reveal the essence of the nonlinear behavioral changes observed during adolescence" (Casey et al., 2008). Given the uneven maturation of the limbic system and prefrontal cortex, B.J. Casey and co-authors in 2008 attempted to derive a new biopsychosocial model of adolescent risk behavior called emotional reactivity. The biological component of this model is based on a more developed and more robust limbic system. The social element is an emotionally significant situation that affects the individual in a certain way. The essence of the psychological component is the ability to assess the surrounding reality objectively. Based on this, the adolescent, who found himself in an emotionally significant situation, understanding the negative consequences of their impulsive and risky actions, still decides in favor of a more powerful emotional stimulus (Casey et al., 2008).
Thus, adolescence is a period of radical changes in the body, including neuropsychological, which determine the style of behavior and worldview. The adaptability of the process of passing this age period can affect the individual's entry into a system of complex social relations, i.e., his socialization. Therefore, it is advisable to consider the features and ways of socialization of adolescents in modern society.

The problem and ways of socialization of adolescents
Each individual as a member of a particular sociocultural environment in its ontogenesis undergoes a process of socialization, i.e., adaptation to the requirements of the society in which he lives. From the total number of definitions of socialization, two main areas can be distinguished. From the first direction, the basic social cognitive principles assume that the basis of socialization of the individual is the immediate environment, which, activating or inhibiting the development of the child, provides the formation of different styles of behavior and worldview (Harden et al., 2016). At the heart of another direction is the idea that successful socialization can be favorable when changing the conditions of the social environment that affect cognition and behavior (Kesebir et al., 2010).
Thus, socialization is a specific interaction of the individual with a vast number of different conditions that affect its development. These conditions are called factors. The socialization process is not always successful and is accompanied by the influence of various stressors and, to some extent, is one of the risk factors for individual health. According to D. Rivera, the study of the main types of factors influencing the socialization of adolescents contributes to a better understanding of their imperative influence on physiology and behavior (Rivera et al., 2020) Among the scientific studies on the problem of socialization, most focus on studying the features of this process in children of early and middle childhood, as these are the age periods of the most favorable changes in development. At the same time, the socialization of adolescence has its unique aspects, which are expressed in the formation of independence, selfsufficiency, self-realization (Smetana et al., 2015).
In general, socialization refers to how adolescents acquire the skills of competent and successful functioning as members of their sociocultural environment (Han et al., 2014). However, the socialization of adolescents depends not only on external conditions. Their development in socialization occurs under the influence of internal individual characteristics that promote or hinder self-development, self-realization, and integration into society. In this case, the individual affects himself as a social object (Kesebir et al., 2010). Thus, the interaction of social environment, culture, and personality is influenced by certain groups of mechanisms, the first of which is interpreted as a mechanism of socialization of the individual, and the second as a mechanism of change of social environment and culture, provided by the integration of social adaptation and internalization.
Adolescence is closely linked to the process of finding one's own identity. Therefore, the primary attention in the process of socialization should be paid to innate individual characteristics, their functions, spiritual values as the foundation of interpersonal relationships, and the attitude of adolescents to them (Martisauskiene, 2014). That is why teenagers are especially concerned about the opinion of their peers. This is due to such neuropsychological features as improving the functioning of areas of the brain responsible for understanding and perception of the opinions of others, increasing the excitability of regions of the brain sensitive to social acceptance or rejection, increasing susceptibility to the manifestation of emotional states of other people. Changes in these brain areas lead to increasing importance for adolescents about their status in the peer group; they become more prone to pressure from them, begin to discuss others more, and evaluate themselves from the standpoint of self-assessment (Mürner-Lavanchy et al., 2020).
Today, scientists from different countries are trying to identify the most typical and effective ways of socialization of adolescents. Some consider the importance of empathy, sympathy, and prosocial behavior in the process of socialization for adolescent development (Şengönül, 2018). Others draw attention to the role of parents in the integration of adolescents into society, his becoming a member of society, ensuring the development of his autonomy and self-esteem (Soenens & Vansteenkiste, 2020). Others note the effectiveness of emotional intelligence, determination, perseverance, and self-esteem during socialization (Zélia, 2016). Successful socialization is measured by the established values and attitudes that make up adolescents' social competence (Kim et al., 2015).
All these studies show that the socialization of adolescents is a dynamic process and can change under the influence of significant circumstances or special means. Knowing how a teenager will react in certain situations can teach him to behave in a certain way, by the requirements of the outside world and the norms of the sociocultural environment in which he integrates. Adolescence is a crisis in terms of educational impact. However, suppose we create conditions for each adolescent that ensure the formation of their initiative. In that case, it is possible to promote the formation of the adolescent as a subject of social activity (Martišauskienė, 2014).
Today, the critical condition for the successful socialization of adolescents in such a personal quality as assertiveness. It is manifested and developed through the individual's social experience and his interaction with society (Peneva & Mavrodiev, 2013). The expanded emphasis in adolescents contributes to their effective social adaptation, while its absence can form social incompetence, disharmony, and social maladaptation (Soenens & Vansteenkiste, 2020). Based on this, it should be noted that assertiveness is one of the effective means of overcoming adverse events in the behavior of adolescents and their adaptive socialization.

The concept of personality assertiveness in research
The concept of "assertiveness" in the psychological literature refers to a confident self-sufficient person, independent of external evaluations, able to independently regulate their behavior and be responsible for their actions, take responsibility for their own decisions (Sarkova et al., 2013). The scientific study of assertiveness began in the mid-twentieth century as an assumption that certain mental illnesses may be caused by insecurity or an inability to express one's ideas and feelings openly, to be confident in oneself and one's actions (Pfafman, 2017).
In 1949, the American research psychologist E. Salter first conducted a study of assertiveness, studying the causes of insecurity in depressed patients and reducing its neurotic effects on their personalities. The author concluded that among all the reasons for uncertainty, the key is the physiological characteristics of the individual. Based on this and based on the introductory provisions of the teachings of IP Pavlova, A. Salter suggested that uncertainty is a consequence of the predominance of inhibitory processes overexcitation processes in the central nervous system. Based on this, insecure individuals are inactive, can not openly express emotions and feelings, have difficulty communicating and interpersonal interaction. Summarizing this approach, it can be stated that the author presents confidence as a personal trait, in particular as an innate quality. This interpretation expresses the constant static nature of assertiveness (Pfafman, 2017).
In contrast, J. Wolpe and A. Lazarus quoted in M. Davis and E. Robbins Eshelman (2019) rethought the essence of assertiveness and presented it as an "expression of personal rights and feelings." The authors found that assertiveness is a variable trait and can be developed under favorable conditions. The basis of assertiveness is the constant training of perseverance, confidence, and the ability to defend their rights.
J. Wolpe, studying the psychophysiological features of the process of assertiveness, argued that the basis for changing behavioral styles is "mutual inhibition" as a process in which "in the presence of a stimulus, the reaction that does not cause anxiety is repeated until it changes the unwanted reaction" (1990). Thus, with the help of assertiveness, it is possible to train new styles of behavior in interpersonal interaction while overcoming the negative consequences of anxious experiences that distort communicative interaction. The problem with insecure people is that their social fear becomes the dominant feeling that blocks their social activity.
Subsequently, Lange A.J. and Jakubowski P. viewed assertiveness as "the direct and honest expression of one's feelings, beliefs, thoughts, and needs, the protection of individual rights, and the expression of one's worldview" (Lange & Jakubowski, 1976). According to their concept, in which assertiveness appears within a humanistic-oriented value system framework, purposeful and confident interpersonal communication allows increasing personal freedom. A.J. Lange, D.C. Rimm, J. Loxley developed a program of assertiveness training, which includes a variety of therapeutic procedures designed to promote the effective transmission of states and feelings from one person to another (1975).
F. Rakos noted that assertiveness skills are necessary for selfconfidence, improving communication skills, stabilizing their emotional sphere. The key to assertiveness is the ability to express oneself confidently without resorting to passive, aggressive, or manipulative behavior (Rakos, 1991). It presupposes greater self-awareness and requires considering the interlocutor's needs without ignoring one's interests and compromising one's principles. It is about improving interpersonal skills, ensuring effective communication, and reducing stress through skillful handling of people and situations.
A. Lazarus noted that assertiveness is a form of behavior, not a personality trait. According to his teachings, assertive behavior includes four specific components: denial of a request, making demands, expressing one's feelings, an initiative at the beginning and the end of the conversation (1973).
R. Rakos generalizing approaches to the definition of assertiveness identified the differences of assertive persons: taking into account the interaction of the rights of all participants, the lack of assessment of the dignity of the interlocutor, taking into account the potential negative consequences of their actions. He also found assertive attitudes: openness in close personal relationships; willingness to voluntarily express their thoughts, ask questions and cope with stressful situations without fear; desire to assert their rights and give neutral but decisive answers in impersonal cases (1991).
Among modern researchers, many adhere to the already established provisions about assertiveness and its essence. Still, many scientists aim to expand the understanding of assertive behavior and its impact on the individual's life. Thus, studies of the effect of assertiveness on overcoming negative emotional states are quite relevant today. P. Vagos and A. Pereira propose a cognitive model to justify the development of assertiveness. The authors note that previous individual action patterns may affect the interactive activation of cognitive, emotional, and behavioral structures. It follows that assertive behavior is the assimilation of specific cognitive patterns of interaction that can accumulate and promote social integration (2016). R. Maqbool investigated the relationship between assertiveness, self-esteem, academic achievement, and stress (Maqbool Parray et al., 2020). Khodabakhshi-Koolaee A. and coauthors found the influence of emotional intelligence on the development of assertiveness and self-esteem (2016).
Assertiveness plays a significant role in interpersonal interaction. An assertive person can establish close communicative contacts with others (Eslami et al., 2016). At the same time, assertive people decrease negative emotional states such as fear, anxiety, stress, and depression (Davis & Eshelman, 2008); assertiveness is the basis for reducing anxiety and fear of separation in adolescents (Parmaksız & Kılıçarslan, 2020). Assertiveness is the ability of an individual to assert their rights and easily express their feelings and thoughts and the ability to interact freely with others without undue anxiety. Assertiveness is a part of personal potential and a prerequisite for successful self-actualization (Peneva & Mavrodiev, 2013).
Thus, most definitions of assertiveness emphasize the direct expression of feelings, desires, and thoughts in interpersonal spheres. Scholars conceptualize assertiveness as an immediate and appropriate expression of their own needs and ideas without humiliating others. That is, assertiveness is an essential, initial trait, thanks to which the individual has the opportunity to cope with their problems and generally thrive, asserting their dignity.

Assertiveness is a factor in the socialization of adolescents
Socialization as a process of entering the social norms and social relations system for a teenager is a prerequisite for establishing personal contact with the outside world. The success of socialization provides adolescents with the achievement of their own identity, self-development, and self-realization (Martišauskienė, 2014). Therefore, effective socialization is due to adolescents' developed confidence, determination, and perseverance, in other words, assertiveness. It is assertiveness that ensures the achievement of the goal, establishing new contacts with others, developing self-esteem and confidence, determination, and perseverance.
Assertiveness is an essential social skill of adolescents that improves their well-being. The level of assertiveness can be influenced by factors such as fear of negative evaluation, especially in social interaction situations (Himaja & Kiran, 2021).
Assertiveness promotes responsibility for behavior, self-esteem, and self-confidence. Confident adolescents are more satisfied with their lives (Sarkova et al., 2013). At the subjective level, assertiveness reflects the ability of the individual to set goals and plan the stages of their achievement while maintaining an advantageous position about himself and others; ability to establish and sustain communicative contacts with other people. Assertiveness helps to take a clear moral position to himself, to others and, based on this position -in some way to achieve their life goals. In this context, assertiveness can be seen as the moral basis of adolescent socialization (Han et al., 2014).
The research results show that there are differences in the neuropsychological processing of information obtained, which determine the perception of moral norms and rules. When adolescents assess different types of ethical situations, other areas of the brain are activated. Thus, in determining personal moral problems, the response is more emotionally significant, while impersonal moral dilemmas are, in most cases, based on conscious and controlled thinking (Caravita et al., 2020). Thus, the importance of deciding on the ethical dilemma situation affects the neuropsychological processes involved in assessing the situation. Based on this, H. Han and his colleagues found that "compared to impersonal moral dilemmas, personal moral dilemmas cause a longer response time and activation in different areas of the brain" (2014). Analyzing such data, it can be noted that assertiveness, as the ability to assess the situation and react decisively morally, reflects the higher cognitive development of the adolescent.
Assertive adolescents are characterized by the complexity and variety of behavioral reactions and have a diverse, contradictory nature of the expression of emotional states. Non-assertive adolescents, at the same time, are marked by conformism, dogmatism, which in adolescents is expressed in stubbornness, the tendency to demonstratively external behavior (Gegajo & Vargas, 2018). Such qualities complicate the process of interaction with the environment, intensifying negative emotional experiences and complicating socialization.
Assertiveness can also affect the social adaptation of adolescents, which is an essential indicator of successful socialization. Adolescents with developed assertiveness see a stressful situation as a challenge and an opportunity to express themselves, while adolescents with low assertiveness assess it as a threatening situation (Parto, 2011). Applying a problem-solving model in behavior usually implies that practical problem-solving usually requires time and systematic effort. And this, in turn, contributes to the development of assertive response skills at the psychophysiological level (Eslami et al., 2016). Adolescents with high assertiveness in stressful situations demonstrate a complex model of automatic response. It follows that the development of assertive behavior reduces anxiety in adolescents' interpersonal relationships and physiological signs of stress.
High assertiveness and confidence contribute to the autonomy of the adolescent's personality and, accordingly, increase the success of his socialization (Parmaksiz & Kılıçarslan, 2020). Studies show that adolescents with low assertiveness have low communication skills, inconsistent thinking, negative self-expression, inability to resolve conflicts constructively, and negative feelings and emotional states, common social adaptation (Simarmata & Anizar, 2018). In turn, promoting the development of assertiveness can provide enhanced social skills and interpersonal relationships (Simarmata & Anizar, 2018).
Assertiveness is a trait that promotes the development of assertive communication -the ability to speak and communicate in a way that respects the rights and opinions of others while upholding their rights, needs, and personal boundaries (Parveen, 2015). The results of studies confirm the effectiveness of assertiveness in increasing adolescent self-esteem, relationship satisfaction, and perseverance, and at the same time reducing clinical manifestations such as anxiety and depression (Shanmugam & Kathyayini, 2017;Speed et al., 2017;Yılmaz et al., 2019;Zeigler-Hill & Shackelford, 2020). This ensures successful socialization and positive relationships with the environment.
Adolescents experience cognitive, biological, and emotional changes accompanied by negative behavioral responses, such as aggression. Given the possible dynamic pressure from peers in adolescence, assertiveness plays an essential role as a social skill of confident behavior. Increasing assertiveness and self-efficacy helps to reduce aggression (Mofrad & Mehrabi, 2015). At the same time, the reason for aggressive behavior, scientists call the lack of adolescent skills of assertive communication, which is the ability to convey thoughts, feelings, needs, taking into account the interests and needs of others (Yuliani et al., 2020).
Other authors have also found that assertive adolescents have high self-esteem, which contributes to their entry into society, the formation of self-confidence, which in turn reduces negative behaviors (Zélia, 2016). In particular, assertiveness is an effective tool in preventing such negative phenomena of socialization as drug use (Indah et al., 2019) and bullying (Utami et al., 2019).
During socialization, adolescents may manifest several stressful situations that they will have to face in everyday life and the stages of their maturation. Assertiveness is often seen as a balance between passive and aggressive behavior. Being assertive for adolescents means respecting other people's thoughts, feelings, and beliefs by taking responsibility for one's actions (Nair, 2021).
Based on the analysis of scientific sources, it can be stated that assertiveness is a crucial parameter of successful socialization of adolescents and contributes to the formation of such positive qualities as empathy, communicative competence, self-esteem, autonomy, self-efficacy, and more. However, the development of assertiveness can help reduce aggression, anxiety, depression, fear, bullying, and more. Assertiveness, according to the principle of determinism, has its conditions and factors of development. The external conditions of assertiveness include the peculiarities of family and school upbringing, the influence of reference groups, personal social experience, etc. To the internal states of development -the basic needs, the formation of the relevant individual psychological characteristics of the individual.

Conclusion
Adolescence is marked by rapid hormonal and psychophysiological changes that inevitably lead to various deviations in adolescent behavior. Excessive emotional excitability, instability, imbalance of the central nervous system, unformed response system in stressful situations all complicate the process of socialization of adolescents in the social environment of society. At the same time, the development of assertiveness can balance the psychoemotional state of adolescents. To promote the establishment of interpersonal interaction and facilitate the process of self-affirmation. The favorable emotional background of assertive behavior fixed in structures of mentality can further considerably define the formation of a communicative type of person, direct on achievement of success, promote the development of motivation, independence, and, ultimately, success in terms of personal socialization.
The development of assertiveness makes it possible to find selfconfidence, change aggressive behavior to calm, learn to defend their rights without violating the rights of others. With the help of assertiveness, the teenager sets goals, plans to achieve them and adjusts the progress of tasks. Adolescent assertiveness is mediated by the motivation of self-affirmation, the dominant value orientations of the reference group, the specifics of the interests and ideals of the adolescent subculture. In adolescence, assertive behavior provides a steady tendency to independence, self-affirmation, selfrealization, which leads to strengthening and deepening the desire of the individual to participate in socially valuable affairs, which ensure the formation of socially significant worldview and success of socialization.