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Abstract

Encouraged by the broad applicability of the primacy of emotional developmental age in addressing challenging behavior, we decided to construct and validate a new comprehensive model of socio-emotional development (SED) for the age range from 0 to 25 years. Guided by the premises of the Dynamic Systems Approach, this article outlines the initial phase of the construction process that focuses on the interactive processes underlying SED. We argue that SED results from the synergistic relationship between five core developmental domains, propelled by ongoing interactions between emotion, cognition, and social environment. These interactions take place in the form of regulated affective transactions within an attuned caregiver-child dyad, as well as within dialogues with the socio-cultural environment at a later age. After identifying seven developmental phases for the intended age range, we constructed a conceptual framework integrating phases and domains. Upcoming articles will describe how this framework forms the basis for the identification of core milestones, resulting in the construction of our intended theoretical model of SED.

Keywords

socio-emotional development developmental processes developmental domains developmental phases interactive developmental theory

Introduction

One of the central premises of the Dynamic Systems Approach posits that human development is the result of a multitude of interrelated and synchronously maturing ontogenetic pathways (De Ruiter et al., 2019). As a consequence, under the conditions of typical biological and neural development as well as normative parenting practices, emotional, cognitive, and social development also occur in synchrony with each other (Sappok et al., 2022; Skelly et al., 2025). However, over the past decades, professionals and researchers in the care of people with intellectual disabilities have repeatedly found that a range of factors, including neurodevelopmental impairments, attachment difficulties, or significant childhood trauma, may lead to a desynchrony to occur, where emotional development is delayed in relation to social and cognitive development (Hermann et al., 2022; Sappok et al., 2021). Because individuals with such emotional delays are typically approached according to their level of cognitive or social functioning, their emotional needs are ignored, which can lead to mental and behavioral problems (Hudson et al., 2024). Once these needs are identified based on an assessment of their emotional developmental level, intervention programs can be developed to address them (Došen, 2005b; Sappok et al., 2022).

To identify emotional delays, Došen (2005a) constructed the Developmental Dynamic Model (DDM). The model proposes that typical emotional development progresses through five phases:

Adaptation (0–6 months): associated with physiologic regulation and sensory integration

Socialization (6–18 months): associated with the development of object permanence and building attachment relationships

First individuation (18 months to 3 years): exploration from a secure base; developing a sense of self and autonomy

Identification (3–7 years): development of theory of mind (mentalization), establishing peer relations, aggression regulation, and compliance in formal educational settings

Reality awareness (7–12 years): reflective thinking, logical reasoning, moral action

Each phase is characterized by specific developmental tasks. These tasks are associated with specific needs, like: predictability of place, time, persons, and activities (1^st phase), bodily contact and availability of attachment person (2^nd phase), affirmation of a certain degree of autonomy (3^rd phase), availability of identification figure (4^th phase), and affirmation of own abilities, productivity, and creativity (5^th phase). One of the objectives of the developmental-dynamic approach is to ensure that daily care meets these needs, which is considered essential for personality development (Došen, 2007; Sappok et al., 2021, 2022).

Tools have been derived from the DDM with the aim of assessing emotional developmental levels in terms of early and middle childhood reference ages (Leal & Hudson, 2025). These assessment tools are based on a conceptual framework consisting of a series of domains in which emotional development is thought to occur, with developmental milestones for each of the five developmental phases. The DDM has been found to be particularly useful in adolescents and adults, as challenging behaviors in these groups are typically associated with significant delays of emotional development, corresponding to such early reference ages (Hermann et al., 2022; Meinecke et al., 2024).

Došen's ideas about the primacy of emotional developmental level in addressing mental and behavioral problems can be considered groundbreaking (Hudson et al., 2024). The importance of the dynamic developmental approach for intervention programs in clinical practice has also recently been empirically established (Skelly et al., 2025). However, while the DDM has gained wide application in the care of people with intellectual disabilities in several Western European countries over the last three decades, its conceptual framework of domains, developmental milestones and phases, including discrete age limits, has never been subjected to empirical verification as advocated by De Groot (1994). In addition, a clear conceptualization of the term emotional development is lacking (Gielen, 2024). Consequently, the validity of the DDM and the empirical robustness of the assessment tools derived from it remain unknown (Gielen, 2016).

Given these shortcomings, we decided to construct a new phase model, including the identification of core domains of typical socio-emotional development (SED). Where Došen speaks of emotional development, we prefer the term SED, as the concept of emotional development is limited to self-oriented or intrapersonal capacities like the abilities to adequately recognize, regulate and express one's own emotions (Malti & Noam, 2016). The concept of SED has a broader dichotomous meaning, also encompassing interpersonal or other-oriented capacities such as the abilities for empathy, perspective taking and cooperation (Schoon, 2021). Since our primary goal is to design a model that allows for the application of the primacy of SED age in the broad field of mental health care for intellectually normally gifted children, adolescents, and adults, it should reflect typical SED up to 25 years of age. Around this age, the brain maturation processes underlying cognitive development are considered complete (Wright & Kutcher, 2016).

The theoretical model to be constructed aims to integrate contemporary developmental theories and research findings on the various topics that can be related to SED from infancy through emerging adulthood. Examples of such theories are: development of the self (Rochat, 2003, 2004a, 2004b) and self-representation (Harter, 2003; Kegan, 1982), emotion understanding (Widen & Russell, 2008), emotion communication (Saarni et al., 2006), emotion regulation (Holodynski & Friedlmeier, 2005), psychosexuality (Sandfort & Rademakers, 2012), social play (Parten, 1933), empathy (Hoffman, 2000), morality (Kohlberg, 1984), the development of discrete emotions (Lewis, 1997; Sroufe, 1982), or identity formation from the late teens through the twenties (Arnett, 2000). Our pursuit of such a comprehensive integrative conceptualization is in line with Thompson's plea to bring together the different domains of SED into one overarching and coherent model, in order “to reassemble the ‘whole child’ from the panoply of developmental influences that tend to be studied independently by researchers” (Thompson, 1993, p. 397). Our model aims to bring together developmental influences up to emerging adulthood.

This article aims to describe the initial phase in the construction of our new theoretical model, focusing on the interactive processes underlying SED. With this goal in mind, we have turned to the principles from evolutionary developmental psychology. An explanation of these principles is necessary since the Developmental Systems Theory states that ‘there is no separation between development and evolution’ (Molenaar et al., 2014, p. 7) with the result that ‘ontogenetic progression may resemble in part the progression that might have happened at the scale of human evolution’ (Rochat, 2004a, p. 175). To begin, Section 1 outlines how a set of premises from the Dynamic Systems Approach led us to identify five core domains of SED from the literature. Together, these five domains constitute and substantively define SED. The mutual influence of the five core domains is also discussed in more detail. As a next step in building our treatise on the conceptualization, Section 2 delves deeper into the role of cognition in SED. More specifically, it addresses the interplay between emotion, cognition, and social environment, which is considered to be the driving force behind the ontogeny of the developmental domains. On the basis of an extensive review of the literature, this Section also describes the identification of seven benchmarks of cognitive growth that exert a pervasive influence in such a way that they give rise to significant synchronous developmental transitions across the five domains. The benchmarks make it possible to distinguish seven developmental phases for the intended age range from 0 to 25 years. In Section 3 we argue that the interplay between emotion, cognition, and social environment manifests itself in the form of the child's regulated affective transactions with the socio-cultural environment. More specifically, these affective transactions take place in the context of primary and secondary intersubjectivity in the early years of development (Trevarthen, 1993) as well as collaborative interacting from the age of 3 (Tomasello & Hamann, 2012). In the concluding Section 4 an integrative conceptual framework of seven developmental phases and five developmental domains is presented.

In upcoming articles we will be using this framework as a basis for the identification of core milestones of SED, which will be assigned to the respective phases and domains, completing our model. To ensure the empirical robustness of the final model, hypotheses regarding the phases, domains, and milestones as relatively independent entities will be formulated and empirically tested. This will provide a validated theory, from which empirically robust tools for assessing SED ages across a series of domains can be derived. The purpose of determining such developmental ages is to identify corresponding socio-emotional needs that can be met with specific intervention programs to promote personality development.

The Identification of Five Interacting Core Domains of SED

SED Through the Lens of the Dynamic Systems Approach

Lewis and Granic (2000) point out that nativist theories with their emphasis on hard-wired and prespecified emotions, constructivist approaches with their focus on cognitive schemas of increasing complexity, and functionalist models that consider individual adaptation to social, cognitive, and biological circumstances as a central feature, cannot adequately explain the non-linear nature of emotional development with sometimes unpredictable or atypical developmental outcomes. Research into emotional development should require an approach that takes into account the non-linear, dynamic, and self-organizing nature of emotional developmental processes that lead to the emergence of novel developmental phenomena. In our view, the Dynamic Systems Approach meets this requirement, because it presents a set of premises that describe behavior as the emergent product of a self-organizing, multicomponent system evolving over time (De Ruiter et al., 2019).

Tomasello (2019) has postulated a set of general assumptions on human ontogeny that reflect these premises. Central is the epigenetic perspective that focuses on the emergence of phenotypes. According to Tomasello, human development is the result of the interrelation of a set of ontogenetic pathways. A given ontogenetic pathway only develops under the developmental constraints created by many other pathways. They do not progress according to some gradual or linear pattern, but rather unfold in a discontinuous way as a result of their interaction with environments and with one another to create phenotypes. In Tomasello's words:

‘Over evolutionary time, an ontogenetic pathway may change in content (for example, the presence or absence of some psychological competency), in timing (when the competency first emerges and how long it takes to develop), and in plasticity (the degree to which the competency is open or closed to environmental influences) (p. 22). …. interactions among developmental pathways – as one or the other of them changes – can be the source of major and unexpected evolutionary novelties. Such changes in timing can have momentous effects on phenotypes by creating novel interactions among pathways, with cascading effects as ontogeny proceeds’ (p. 23).

We consider Tomasello's premises on human ontogeny fully applicable to the construction of our model of SED. In doing so, we respond to Camras and Witherington's call for the application of the principles of the Dynamic Systems Approach ‘to provide a unifying framework for a comprehensive theory of emotional development extending across infancy, childhood, and perhaps adolescence and beyond’ (Camras & Witherington, 2005, p. 345). Inspired by Tomasello's premise that human development is the result of bidirectional influence of developmental pathways resulting in the emergence of phenotypes, we searched the literature for those developmental pathways that, in their interaction, are believed to constitute SED. In the subsequent paragraphs, we explicate how five specific developmental pathways, in the context of our model referred to as domains, are derived from the extant literature, shedding light on the nuanced dynamics that underlie the unfolding complexities of human SED.

Self-Development and Development of Social Relatedness as Two Central Domains

In the context of their plea for a more dimensional approach of DSM-diagnostics, Luyten and Blatt (2013, 2016) put forward that personality development evolves through a dialectic synergistic interaction between two fundamental developmental psychological processes across the life span. These two processes are the development of interpersonal relatedness (the capacity to establish and maintain reciprocal, meaningful, and personally satisfying interpersonal relationships) and self-definition (the capacity to establish and maintain a coherent, realistic, differentiated, and essentially positive sense of self, or an identity). In personality development, an increasingly differentiated, integrated, and mature sense of self emerges out of constructive interpersonal relationships and, conversely, the continued development of increasingly mature interpersonal relationships is contingent on the development of a more differentiated and integrated self-definition and identity (Luyten & Blatt, 2011). As a result, both interpersonal relatedness and self-definition can be regarded as two fundamental developmental dimensions, also referred to as central coordinates (Luyten et al., 2017; Luyten & Blatt, 2013, 2016). A similar point of view is formulated by Livesly (2008), who argues that dysfunctions in the domains of relatedness and self-definition are the core of the etiological factors in the development of personality disorders.

Since, in our view, the interactive processes of personality development parallel those of SED, the synergistic relationship between self-definition and relatedness also applies to the construction of our model of SED. For this reason we include self-definition and interpersonal relatedness as two separate domains in our model under the names self-development and development of social relatedness respectively.

Emotion Differentiation, Development of Emotion Regulation, and Moral Development as Three Complementary Domains

As the concept of SED transcends the combined domains of self-development and development of social relatedness, it becomes imperative for the concept to also incorporate other contemporary issues that dominate the developmental literature. The range of theories on emotion development listed in the Introduction, as well as publications on the crucial role of emotions and their regulation in human development (e.g.,: Gross, 2008; Thompson, 1993, 2001) made us realize that emotion differentiation and emotion regulation should be included in our model as two conceptually distinguished but interacting domains. Since both domains are functional to the major developmental transitions that serve the child's adaptation to a constantly changing social environment (Holodynski & Friedlmeier, 2005), they are considered indispensable in a model of SED. Finally, moral development should be regarded as a necessary domain. Not only is morality considered an innate core aspect of human development (Hamlin, 2013), but it is also regarded as an integral part of self-definition, referred to as the moral self (Kochanska, 2002; Krettenauer et al., 2013; Tomasello, 2019; Tracy & Robins, 2004). Morality calibrates human ontogeny according to the prevailing standards of intra- and interpersonal functioning and is an effective guide to adaptive social interacting (Hamlin, 2014. In addition, morality is strongly intertwined with the domain of emotion differentiation, where, for example, the self-evaluative moral emotions of guilt and shame (Eisenberg, 2000), sense of fairness (Engelmann & Tomasello, 2019), the innate capacity for moral intuition (Baillargeon et al., 2015), or feelings of compassion and empathy (Hoffman, 2008) have been given a place. Finally, moral rules and habits have a strong influence on self- and emotion regulation (Hamlin, 2014). In short, because moral development is inextricably linked to adaptive social functioning and is considered inherent to self-definition, self-regulation, and emotion control (Hinde, 2002), it should be included as a separate domain within a model of SED.

In our view, with the addition of emotion differentiation, development of emotion regulation, and moral development to self-development and development of social relatedness, the five major domains together constituting SED have been identified. In accordance with Tomasello's premise of the mutability (change in phenotypic expression) of an ontogenetic pathway in the form of the emergence of ever new phenotypes, the domains serve as overarching theoretical constructs aiming to categorize and accommodate the milestones of SED. Presented as the five core domains, they constitute SED as an integral major component of personality development.

The Interactive Operation of Five Core Domains of SED

One of the main premises of the Dynamic Systems Approach concerns the interactive nature of developmental pathways. We found good indications in the literature for the existence of such an interactive capacity. Holodynski and Friedlmeier's developmental model of emotional action regulation (Holodynski & Friedlmeier, 2005) describes the process from perfect co-regulation during the first two years of life to internalized emotion regulation from the age of 6 years and shows how an adaptive interpersonal and intrapersonal regulation of emotions is at the basis of further emotion differentiation. The model provides insight into how the child, on the basis of the capacity for appropriate emotion regulation, becomes equipped with new emotion-cognition schemas (see: Section 2.1) arising from an increasing integration of cognitive appraisals of new challenges and circumstances. Such adapted and evolved schemas are functional to the developmental tasks corresponding to each new developmental phase. Although Holodynski and Friedlmeier mainly focus on the development of emotions and their regulation, their model also has implications for self-development. Both the objective component of an emotion, including the expressive and bodily aspect, and the subjective component, consisting of the subjective feeling, must be regarded as experiences and manifestations of the self.

Not only is the self the acting agent of intrapersonal and interpersonal regulation, but all qualitatively higher forms of emotions that arise from an appropriate action regulation are integrated into the self. This principle is at the basis of self-development and suggests that self-development cannot be separated from the development of emotion regulation and emotion differentiation. In addition, emotion regulation and the integration into the self of higher-quality forms of emotions have consequences for the development of social relatedness. After all, the development of new action regulation systems (i.e., new emotion-cognition schemes) not only allows the child to adapt to new and more complex social interactions, but also to regulate the emotions that hinder adaptive interacting. Children who are better at regulating their emotions will be less likely to experience self-oriented personal distress in response to others’ misfortune and more likely to experience other-oriented sympathy and empathy responses (Eisenberg, 2000; Eisenberg et al., 2014). This finding is in line with the view of Krol and Bartz (2022) who state that the capacity for appropriate empathic responding is influenced by the degree of self-other differentiation. Without adequate self-other distinction, sharing another person's emotions can induce personal distress, a self-focused aversive reaction that often leads to withdrawing from the situation, rather than empathic. Stifter and Augustine (2019) note that both advances in cognitive and motor skills and the emergence of specific emotions are important for the development of emotional regulation, including the regulatory strategies used by the young child. In sum, from an ontogenetic perspective, emotion regulation and emotion differentiation are inextricably linked to each other, as well as to self-development and development of social relatedness. Both domains can be regarded as fundamental to SED, since they appeal to emotions as action systems (Frijda, 2008) and action regulation systems (Holodynski & Friedlmeier, 2005) resulting in motivational states and readiness to act (Abe & Izard, 1999; Izard, 2007, 2011).

Section 3 below elaborates on the interplay between experiences of the self (domain of self-development) and the capacity to establish interpersonal connections (domain of development of social relatedness). More specifically, it describes how the integration into the child's self of the regulated affective transactions with the social environment constitutes the true driving force of SED. Finally, with regard to the domain of moral development, Section 1.3 already pointed out the ontogenetically close intertwining of morality with the other four domains. The interactive operation between the five core domains of SED is shown in Figure 1.

Figure 1.

Interactive functioning of five core domains of SED. Note.

The Role of Cognition in Socio-Emotional Development

The Reciprocal Influence of Emotion and Cognition in a Social Context

Nowadays, it is generally accepted that emotions play a vital role in early human development. Thompson (2001) summarizes the significance of emotions as follows:

‘Emotions are regarded as centrally important to understanding development in infancy and childhood….Emotional development offers a unique integrative perspective on human development.… (it) is central to understanding the growth of social competence, intellectual achievement, self-understanding, and the earliest origins of mental health or psychopathology because of the importance of emotion to the organization and regulation of early behavior. Emotional development provides a window into the psychological growth of the child’ (p. 7382).

However, notwithstanding the vital role of emotions in early childhood, developmentalists underline that human ontogeny is the final result of a fundamental interplay of emotion, cognition, and social environment (Clark et al., 1993; Denham & Holt, 1993; Izard et al., 1991; Rochat, 1995; Sameroff et al., 1998). Several publications on early development point to the close and interactive connection between cognition and emotion (Cicchetti & Pogge-Heese, 1981; Cicchetti & Sroufe, 1976; Sroufe, 1979, 1996). Campos and Barrett's functionalist perspective about the importance of cognitive appraisal of emotions (Campos & Barrett, 1984), Lewis’ theory on the role of consciousness in emotional development (Lewis, 2014), Lindquist's constructionist model which claims that emotions are mental events created in the perceiver's mind to fit a certain situation (Lindquist, 2013), Sroufe's hierarchical model of the organization of emotion development (Sroufe, 1996), and Panksepp's view on the neurological hierarchical organization of emotion-cognition interactions (Panksepp, 2003, 2005), are all examples of how interaction of emotion with cognition contributes to emotional development. Due to maturation processes in the prefrontal cortical brain areas, the role of cognition becomes increasingly important over the developmental years (Wright & Kutcher, 2016).

But how should this fundamental interplay be conceived? In other words, is there a theory that describes in a coherent and insightful way how the interaction between emotion, cognition, and social environment constitutes SED including the emergence of core developmental milestones? In our opinion, the Differential Emotions Theory (DET) (Abe & Izard, 1999; Izard, 2007, 2009, 2011; Izard & Malatesta, 1987) meets this criterion. According to DET, early in ontogeny a core set of emotions begins to interact with cognition to form emotion schemas. An emotion schema is emotion that dynamically interacts with perceptual and cognitive processes. Along with first-order emotions, emotion schemas constitute the principal motivational and regulatory systems for human behavior and represent ways of engaging others and aspects of the environment. They play a decisive role in self-regulation, planning, decision-making and action. In contrast to first-order emotions, emotion schemas depend on continued interaction among the neural substrates of both emotions and higher order cognition (Izard, 2011). The cognitive content of emotion schemas enhances the regulatory, motivational, and functional capacities of their feeling components. Emotion schemas are fundamental to human development since they are central to the emergence of major developmental phenomena. In the words of Abe and Izard (1999):

‘….the major developmental milestones do not emerge as wholes at a particular age simply as a consequence of cognitive attainments, but rather emerge gradually through social interactions and involve the interplay of the emotions and cognitive systems. Emotionally laden transactions with the environment are likely to stimulate qualitative advances in social-cognitive functioning and, in turn, advances in social-cognitive functioning are likely to contribute to emotional development. Thus, the emotions and cognitive systems are seen as reciprocally influencing one another to help the developing child adapt to the changing demands of the social environment’ (p. 527).

We consider DET's premise that emotionally laden transactions with the social environment are the synergistic forces underlying the emergence of developmental milestones fully applicable to the construction of our model of SED. Consequently, the concept of SED aims to express that emotion-cognition interactions, with an increasing role of cognition over the course of development, are always embedded in a social context for the purpose of adapting individuals to the social world. The interplay between emotion, cognition, and social environment is considered to be the driving force behind the ontogeny of the developmental domains of our theoretical model.

Identification of Seven Benchmarks of Cognitive Growth

The traditional debate has always been whether development proceeds in a discontinuous manner according to a succession of stages of behavioral organizations, each having a certain closure, or as a gradual continuous process of accretion and growing sophistication (Liebert et al., 1974; Rochat, 2004a). Despite the objections that the premise of a phase-bound developmental pathway does not explain the asynchronous course of some specific developmental trajectories of, for example, linguistic abilities or sensorimotor skills (Rochat, 2004a), and that personality traits remain relatively constant across age (Schaffer, 2006; Specht et al., 2014), we found reports of major developmental transitions at specific ages as a result of benchmarks of cognitive growth.

The first benchmark concerns the pre-reflexive form of self-experience at birth. On the basis of an inborn cognitive-mentalizing capacity, an ecological self is constructed in the last phase of pregnancy from the invariant aspects of proprioceptive and other multisensory experiences (Finlay & Uchiyama, 2020; Rochat & Striano, 2000) and can be differentiated by the newborn from stimuli from the outside world (Rochat, 2004a, 2011).

The second benchmark refers to the cognitive capacity for self-other differentiation, which emerges from the age of 7 months. It enables the child to understand others as intentional agents (Rochat, 2004a) and paves the way for joint intentionality (Tomasello, 2019), social referencing (Thompson, 2006), moral intuition (Hamlin, 2013), and empathic concern (Hoffman, 2008), including offering help and sharing assets (Warneken, 2015).

The third benchmark, referred to as cognitive self-awareness (Broesch et al., 2011), can be observed from 18 months of age and is truly a developmental milestone as it is a catalyst for the occurrence of developmental phenomena like embarrassment, pride, joy, and shame (Lewis, 2014), as well as the prosocial and moral emotions of empathy, sympathy, and guilt (Spinrad & Eisenberg, 2019).

The fourth benchmark concerns the internalization of language at about the age of 3. Using language allows toddlers to communicate more specifically about their needs, suggesting that an increase in language skills is accompanied by a decrease in expressions of anger (Roben et al., 2013). In addition, the internalization of speech gives rise to the emergence of the ability to internalize conventional and moral standards. Concerning emotion regulation and moral development, the child no longer depends on the caregiver's physical contact, proximity, or ostentatious instructions, but prescribed behaviors, commandments, and prohibitions are complied with independently and autonomously. At the same time, the self-regulating capacity to conform to conventional and moral standards paves the way for the emergence of collective intentionality, when children become group-minded and commit to a ‘we’ that is greater than ‘me’. This capacity enables the child to enter the world of peers around the age of 3 (Tomasello, 2019).

The fifth benchmark presents itself around the age of 7 years, when children enter the ‘age of reason’. Based on a cognition-driven introspective capacity to understand one's own motives, objectives and reason for taking action, a sense of responsibility emerges, allowing children to be held accountable for their deeds, as well as for self-regulating their beliefs and actions in accordance with cultural norms, just like they, too, hold others accountable (Tomasello, 2019).

The sixth cognitive benchmark emerges around the age of 12, when, under the influence of further brain development, particularly in the prefrontal and temporal cortical areas, higher forms of abstract and hypothetical thinking become possible (Wright & Kutcher, 2016). This benchmark is typically associated with the fourth and final phase of Jean Piaget's theory of cognitive development, known as the formal operational phase (Senan, 2013). It marks the beginning of adolescence and continues into emerging adulthood. In addition to the integration of gender-specific bodily changes as experiences of the self, achieving autonomy, that is, establishing oneself as a separate self-governing individual, becomes a major task of the adolescent (Berk, 2003; Steinberg & Silverberg, 1986). Autonomy is closely related to adolescents’ quest for identity, including building self-reliance, work orientation, academic competence, and self-esteem (Lamborn & Steinberg, 1993). Moreover, adolescents may be very preoccupied with being liked by others, with particular concerns about body image, appearance, and clothing. Romantic or sexual relationships may arise, sometimes resulting in long-term commitment. In particular, the early adolescent is confronted with moodiness, which he or she will have to learn to deal with when interacting with authority figures or peers. Finally, a growing sense of right and wrong develops, while personal and moral values appear as key themes in older adolescents’ self-concepts (Harter, 2003). All of these and other aspects should be included as significant developmental milestones within each of the domains of our model, making adolescence a very prominent period of human ontogeny. We have given the sixth cognitive benchmark the name ‘striving for autonomy and identity exploration’.

The final cognitive benchmark in our model, referred to as ‘formal and personal responsibility’ heralds the period of emerging adulthood. This period typically spans the ages of 18 to 25, when the prefrontal cortex of the brain, responsible for decision-making, impulse control and long-term planning is fully developed (Hochberg & Konner, 2020). The age of 18 marks the moment where in most Western countries an individual transitions from being a minor to an adult with full legal rights and responsibilities (Schulenberg & Schoon, 2012). The period of emerging adulthood is characterized by exploration of responsibilities in the context of identity formation, with individuals appropriating decision-making power over aspects of their lives such as housing, transportation, education, finance, or healthcare (Roisman et al., 2004). In general, this phase is about determining life direction and goals, learning to be self-reliant, figuring out personal values and beliefs, and building professional and personal relationships (Arnett, 2000). At the same time, during this period, emotion regulation and self-regulation strategies are internalized as part of the self, enabling individuals to appropriately deal with stressful or emotionally demanding situations that may arise in the pursuit of their life goals (Charles & Carstensen, 2007). In summary, the seventh and final cognitive benchmark also leads to the emergence of new core developmental milestones that correspond to the aforementioned developmental tasks, thereby promoting the simultaneous advancement of each of the domains.

In conclusion, we were able to identify seven cognitive benchmarks for the 0–25 age group from the developmental literature. These benchmarks involve, respectively, the emergence of the ecological self in late pregnancy, self-other differentiation from the age of 7 months, cognitive self-awareness at 18 months of age, the internalization of speech and collective intentionality from the age of 3 years, sense of responsibility from the age of 7, striving for autonomy and identity exploration around the age of 12, and formal and personal responsibility from the age of 18. The seven benchmarks of cognitive progress that give rise to developmental transitions within each of the five domains are depicted in Figure 2.

Figure 2.

Seven benchmarks of cognitive growth. Note. The dotted line of cognitive development indicates that it is inseparable part of human ontogeny, but will not be included in our final model (see: Summary and discussion). To the right of the figure, seven pervasive cognitive milestones are identified, affecting each of the domains (dotted arrows to the left).

Obviously, Figure 2 reflects an interactive view: SED manifests itself in a multitude of interrelated and synchronously maturing ontogenetic pathways that unfold according to hierarchically organized qualitative transitions in the form of ever new developmental milestones, as a result of interactions between emotion, cognition, and social environment.

Internalized Affective Transactions with Social Environment as Drivers of SED

Tomasello (2019) points out that maturation plays a key role in structuring human ontogeny and introduces the concept of ‘transactional causality’ to indicate that maturational capacities are inert until they are used in the individual's transactions with the social environment. In the context of our model, the premise of transactional causality takes shape in the affective transactions between the child and its caregivers, as well as peers and trusted adults at a later stage. These transactions are regarded as the true driving force of SED. They contribute to the emergence of ever new developmental phenomena that, in accordance with the principles of the Dynamic Systems Perspective, through their mutual influence cause the five domains to mature synchronously.

In order to understand how the child's affective transactions with the social environment actually take place, three concepts are fundamental: primary intersubjectivity, secondary intersubjectivity, and collaborative interacting. Within primary intersubjectivity, which is the central feature of the early caregiver-child dyad, an exchange of affective experiences takes place, causing the baby to integrate into the self the caregiver's mirrored and regulated responses (Fonagy & Bateman, 2007; Stern, 1985; Trevarthen, 1993). The newborn's capacity to communicate its emotions in the form of affect sharing converges with the intuitive regulating affective responsivity of the caregiver that is typical of a secure attachment relationship. As a result of the caregiver's mirroring affective reactions, the newborn's unfocused emotions gradually acquire the status of functional focused emotions, resulting in a differentiation of emotions of qualitatively higher forms (Holodynski & Friedlmeier, 2005). The synergistic significance of the affect-laden caregiver-child interactions is, that the mirrored affects integrated into the baby's self are at the basis not only of self-development, but also of the development of self-regulation, emotion regulation, and emotion differentiation (Fonagy et al., 2007; Kernberg, 2015; Kochanska et al., 2001; Rochat, 2003, 2011).

The emergence of the capacity for self-other differentiation around 7 to 9 months of age is the prelude to the emergence of secondary intersubjectivity (Trevarthen, 1993). It concerns the ability to assign subjective mental states such as intentions, wants, and desires to the other based on the recognition of a similar or corresponding mental state in the child's self. The ability to recognize separate minds greatly accelerates human development. For example, the capability to identify and express one's own will contributes significantly to the pursuit of one's own autonomy, while the capacity to recognize and label the other's emotional expressions is the starting point of moral development. The ability to reflect on the consequences of one's own behavior initiates the emergence of new emotions such as pride and shame. The recognition of the regulatory affective expressions of the other and their integration into the child's self marks the beginning of an autonomous emotion regulation, while the capacity for joint attention contributes dramatically to the development of social relatedness.

From the age of about 3 years, when the child enters the world of peers, a sense of collective intentionality emerges (Tomasello, 2019). This capacity marks the beginning of the child's collaborative interacting with its social environment. In accordance with the socio-cultural theory of cognitive development of the Soviet scholar Lev Vygotsky (1896–1934), from that age onwards, through verbal dialogues and joint activities with more expert peers and significant adults, culturally determined values, beliefs, customs, and social skills are transmitted as a contribution to the child's cognitive growth (Berk, 2003). Although Vygotsky's theory focuses on cognitive development as a socially mediated process, we argue that its premises also apply to SED. The verbal dialogues of the child and adolescent with knowledgeable members of society undoubtedly extend to the culturally accepted way in which emotional experiences are to be channeled and expressed. Just as children and adolescents internalize culturally determined values, habits, and social skills as a contribution to cognitive growth, so too, for the purpose of SED, they will internalize emotions that are regulated according to culturally established codes. The integration into the self of these social interaction-based modified emotional experiences and responses, including moral thinking and acting, serve SED. Taken together, within primary and secondary intersubjectivity as well as within collaborative interacting, socialization processes take place that are characterized by regulated affective transactions with the socio-cultural environment as driving forces behind the ontogeny of the domains of SED.

Primary and secondary intersubjectivity as well as collaborative interacting occur within the context of secure attachment relationships. Affective transactions will only be integrated into the child's self when the criteria of secure attachment and regulatory and attuned interactions between caregiver and child are met. Research findings indicate the positive association between attachment security in infants and their ability for adaptive emotional and social functioning later in life (Harwood et al., 2008). These findings leave no doubt that secure attachment is a prerequisite for typical SED. Children who are securely attached as infants and preschoolers are more likely to develop adaptive social competences. They have more self-confidence, show more empathy toward others, become popular with their peers, and are more cooperative with adults (Harwood et al., 2008). Securely attached children are less likely to develop emotional or behavior problems than are insecurely attached children (Erickson et al., 1985). They also tend to be better at regulating their emotions and are more skilled as preschoolers in understanding emotions (Brumariu, 2015; Laible & Thompson, 1998; Waters & Thompson, 2016). Such research findings demonstrate that the quality of attachment is of significant importance for the progress of each of the domains of our model of SED. Attachment quality affects the degree of self-awareness and self-confidence, the quality of social competences including the ability to engage in friendships, the capability of appropriate self- and emotion regulation, as well as the capacities for empathy, emotion understanding and social cognition as a basis for moral thinking and acting.

Taken together, SED, understood as the synchronous unfolding of developmental domains, ‘is set in motion’ by the regulated and attuned affective transactions within the context of primary and secondary intersubjectivity in the early developmental years, as well as collaborative interacting at later ages. These transactions not only give rise to self-development and development of social relatedness. Based on a number of precursor emotions and innate abilities and supported by cognitive advances, which in turn are the result of interactions with the social environment, the affective transactions also underlie moral development, emotion differentiation, and development of emotion regulation.

Framework of Seven Phases and Five Domains Underlying a New Model of SED

On the basis of the assumption that SED proceeds according to major qualitative changes at specific age periods, we decided to include in our model a phase structure based on seven benchmarks of cognitive progress for the age range from 0 to 25 years (see: Section 2.2). The identification of seven phases and five domains of SED allows the construction of an integrative conceptual framework that underlies our model to be designed (Table 1).

Table 1.

Integrative Framework of Seven Developmental Phases and Five Developmental Domains.

Developmental Phases	Developmental Domains
Developmental Phases	Self-development	Development of social relatedness	Emotion differentiation	Development of emotion regulation	Moral development
1st phase 0–7 months	milestones	milestones	milestones	milestones	milestones
2nd phase 7–18 months	milestones	milestones	milestones	milestones	milestones
3rd phase 18–36 months	milestones	milestones	milestones	milestones	milestones
4th phase 3–7 years	milestones	milestones	milestones	milestones	milestones
5th phase 7–12 years	milestones	milestones	milestones	milestones	milestones
6th phase 12–18 years	milestones	milestones	milestones	milestones	milestones
7th phase 18–25 years	milestones	milestones	milestones	milestones	milestones

Note. Upcoming articles will describe the process of identification of all key milestones, including their names, allowing for the substantive conceptualization of both domains and phases.

Once the key milestones have been identified and assigned to the respective domains and phases, names can be linked to the phases. Each name is assumed to appropriately typify all developmental milestones across the five domains within one and the same phase. The naming aims to express that there is a common denominator suggesting a certain relationship between the milestones as a result of synchronous transitions at specific ages. After naming the phases, we can present our final model from which hypotheses will be derived and subjected to empirical verification.

Summary and Discussion

Inspired by Došen's groundbreaking ideas about the primacy of emotional developmental age in addressing mental and behavioral problems, we set out to construct a new interactive theoretical model of SED with an age range of 0 to 25 years that allows for the identification of such developmental ages across a range of domains. As a first step in this construction process, we turned to the principles of the Dynamic Systems Approach with the aim of describing the interactive processes underlying SED. More specifically, Tomasello's premise that human development is the result of the interactive operation of a set of ontogenetic pathways prompted us to explore the pathways of SED. As a result, we could identify five core domains that together constitute SED. These domains include self-development, development of social relatedness, emotion differentiation, development of emotion regulation, and moral development. The interactive nature of the model concerns the interrelationship between the domains, propelled by emotion-cognition interactions according to the principles of the DET, which in turn take place in the form of regulated affective transactions within the context of an attuned caregiver-child dyad and of dialogues with the socio-cultural environment at later ages.

Theories on emotional development underline the influence of cognition, which, in the context of Abe and Izard's emotion schemes, becomes increasingly important over the course of development. As a consequence, we were able to identify seven benchmarks of cognitive growth for the age range 0 to 25 years. They are regarded as decisive for the emergence of developmental transitions, which also allowed us to distinguish seven developmental phases and integrate them into our model. But, as one might ask, if cognition plays such an important role, why is cognitive development not considered a domain of SED? The answer to these question is mainly prompted by considerations of conceptual demarcation. Although cognitive development in interaction with other domains contributes to human ontogeny, we consider this developmental domain as a conditio sine qua non for SED. In the context of the construction of our model, it does not require further specification by making the developmental trajectory explicit through the identification of constitutive developmental milestones. If we had to include the milestones of cognitive development, our model would have become a six-domains model. However, when it comes to the question ‘What is SED?’, we wanted, in the context of the conceptualization issue, to demarcate the number of domains in order to keep the concept recognizable.

Another point of discussion concerns the question why we wanted to design a new model of SED and not use existing models as an alternative to the DDM. In other words, what does our model add to existing models? There are a number of well-conceptualized multifaceted models of SED that allow for the assessment of an individual's strengths and weaknesses in terms of competencies and skills within domains of social and emotional development. Examples include the CLOVER model of Malti and Noam (2016), the conceptual frameworks underlying programs to facilitate social and emotional learning (SEL) (Collaborative for Academic, Social and Emotional Learning, 2020; Durlak et al., 2011) or the DOMASEC model as a two-level taxonomy of key domains of SED competences (Schoon, 2021). However, in our many years of practice in mental health care, we noticed a need for an empirically robust model that, like the DDM, offers the possibility to assess developmental ages across a number of domains, in order to identify SED delays as a starting point for designing intervention programs to enhance personality development. The reason for raising this need is that the principle of the primacy of SED age in addressing problem behavior has demonstrated its potential over the past decades in the care of people with intellectual disabilities (Sappok et al., 2021; Skelly et al., 2025). More specifically, the strength of the model lies in the fac that assessment tools derived from it allow to assess actual SED capacities and skills across several domains, thereby determining a person's SED age in each domain. Discrepancies with the capacities and skills a child or adult should possess according to his/her mental or cognitive age lead to the identification of SED needs, which serve as a basis for setting up intervention programs aimed at meeting these needs. With our model, we aim to introduce the primacy of SED age within mental health care for children and adults, precisely because it is not uncommon for mental and behavioral problems within these sectors to be based on delays in one or more SED domains (Abraham, 2005). This starting point makes our model unique.

The conceptualization issue also involves the assumption of a phase-related progression of SED. It led us to implement in our design a seven-phase structure based on benchmarks of cognitive development and to construct a conceptual framework of phases and domains. This framework will be subjected to a hypothesis-testing validation study. With regard to the developmental domains, the following hypothesis will be formulated: ‘All five developmental domains are discrete entities’. As to the developmental phases, the wording reads: ‘All seven developmental phases are discrete entities’. By formulating the hypotheses in this way, the expectation is expressed that, although there is some interdependence between both the domains and the phases, prompted by the premise of the synchronous maturation of ontogenetic pathways, the domains and phases will emerge as relatively independent constructs in data analysis. Parents of several hundred children and adolescents up to the age of 18, as well as a large group of young adults aged 18 to 25, will be asked to complete extensive questionnaires. Specific statistical methods that will be applied to their responses will then clarify the extent to which these hypotheses are confirmed or rejected. With respect to the major developmental milestones yet to be identified, similar hypotheses will be derived and subjected to statistical analyses.

Upcoming articles will explain how the principles of the Dynamic Systems Approach served as a basis for identifying core milestones and their assignment to these phases and domains. The result will be a comprehensive conceptual framework that aims to meet Thompson's call, cited in the Introduction, ‘to reassemble the ‘whole child’ from the panoply of developmental influences that tend to be studied independently’. By subjecting our innovative model to empirical verification, we will offer a validated base to guide future research and practical applications within the various sectors of mental health care.

Footnotes

Acknowledgment

We thank Ross A. Thompson, Professor Emeritus of Psychology at the University of California for his valuable comments, which contributed significantly to the completion of the manuscript. We also thank Jaap Denissen, Professor at Utrecht University for his support at the time of the project, as well as Willem Koops, Professor Emeritus of Psychology for his input in solving various issues.

ORCID iDs

Jan J. M. Gielen

Max J. A. Feltzer

Ethical Approval and Informed Consent Statements

Since no personal data are processed in this article, the regulations of the Ethics Committee of Tilburg University do not apply.

Author Contributions

Jan Gielen: Conceptualization, Writing – Original Draft. Max Feltzer: Supervision, Text Enhancements.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

No empirical data has been collected and is available for this purely theoretical paper.

Author Biographies

Jan Gielen is a PhD candidate with 35 years of expertise as a clinical psychologist in the field of challenging behavior in people with intellectual disabilities. He is a great advocate of applying a client's socio-emotional developmental age as a basis for intervention programs in mental health care. This starting point inspired him to develop a correspondingly innovative theoretical model.

Max Feltzer, PhD, is a developmental psychologist at Tilburg University, Tilburg, The Netherlands (Department of Developmental Psychology). Research interests: socio-emotional and cognitive development, children's drawings. With more than 40 years’ experience in these areas, Dr. Feltzer is currently working on projects involving construction of new theoretical models and new screening instruments to assess psychological development in children aged 0–12 years.

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The Identification of Five Core Domains and Seven Phases as a First Step Towards a New Theory of Socio-Emotional Development

Abstract

Keywords

Introduction

The Identification of Five Interacting Core Domains of SED

SED Through the Lens of the Dynamic Systems Approach

Self-Development and Development of Social Relatedness as Two Central Domains

Emotion Differentiation, Development of Emotion Regulation, and Moral Development as Three Complementary Domains

The Interactive Operation of Five Core Domains of SED

The Role of Cognition in Socio-Emotional Development

The Reciprocal Influence of Emotion and Cognition in a Social Context

Identification of Seven Benchmarks of Cognitive Growth

Internalized Affective Transactions with Social Environment as Drivers of SED

Framework of Seven Phases and Five Domains Underlying a New Model of SED

Summary and Discussion

Footnotes

Acknowledgment

ORCID iDs

Ethical Approval and Informed Consent Statements

Author Contributions

Funding

Declaration of Conflicting Interests

Data Availability Statement

Author Biographies

References