The first social experiences of infants take place, from the first months of life, through interactions with their caregivers and with everyday objects (Moreno-Núñez et al., 2021a). This is consistent with the cultural-historical approach and, more specifically, with the postulates of activity theory developed from Vygotskian proposals. From this perspective, individuals act collectively based on shared activities and communicative exchanges that allow us to appropriate cultural tools (Vygotsky, 1978; Foot, 2014). According to this, social interactions, especially with adults, are essential during early childhood as they favour an inter-communicative space of mediation and collaboration that facilitates the child’s learning and development (Vygotsky, 1984; Veraksa and Veraksa, 2018).

Adult mediation refers to the guided process of equipping children, through shared activities, with the psychological tools necessary to operate in a specific sociocultural context. It enables children to progressively internalise their learning and, consequently, to develop in the world in an increasingly autonomous way (Vygotsky, 1934/1986). Throughout the first year, infants’ relationship with their environment is modified by the intervention of the adult (Vygotsky, 1932/1996; McCune and Zlatev, 2015), who responds to their first signals and attempts to communicate while sharing bouts of attention and action on specific objects or events (Bakeman and Adamson, 1984; Solovieva and Quintanar, 2021). This process does not, therefore, occur in a vacuum, but within the framework of early interactions that take place in a given socio-material context. In these interactions, objects are incorporated not as mere material realities, but as communicative vehicles that encourage joint action based on their social and cultural properties (Rodríguez, 2012; Burner and Svendsen, 2020). Thus, it is in these interactions where the conventional meanings and uses of objects are transmitted (Rodríguez, 2006; Solovieva et al., 2020). This enables progressive sophistication in infants’ actions, by turning these into social acts directed to, and coordinated with, the other person (Carpendale et al., 2021).

The role of these triadic encounters (adult-infant-object) in socio-communicative development has been the focus of much debate, especially over their origin. Traditionally, it has been considered that babies relate first to adults, during the first months of life, and somewhat later, also to objects. This has given rise to the differentiation between primary intersubjectivity, referring to early dyadic exchanges between adults and infants, and secondary intersubjectivity, in which interactions incorporate external referents, acquiring a triadic character (Trevarthen and Hubley, 1978; Carpenter et al., 1998; Tomasello et al., 2005; Striano and Reid, 2006). The transition from one stage to the other is usually considered to take place at around nine months of age, when the infants’ first intentional communicative acts towards the adult emerge in what Tomasello (2013) called the “nine-month revolution.” From then on, the complexity of the infants’ socio-communicative behaviours increases, as they can share experiences with others through, for example, the use of gestures and the diversification of communicative functions (Bates et al., 1975).

However, more recent work questions whether the emergence of infants’ first triadic experiences is limited to the end of the first year (Rodríguez, 2006). Some authors have characterised this process as a continuous and gradual development, mediated by the adult from birth (Reddy, 2010). In this sense, early communication would develop from the beginning of life according to interactional dynamic processes (Fogel and Thelen, 1987; Fogel, 1993; Thelen and Smith, 1994) in which what is shared is not transmitted unidirectionally, from one mind to another, but is jointly created between adult and child (Fogel, 1993; Trevarthen and Reddy, 2017) or within the family dynamics with more than one primary caregiver (Fivaz-Depeursinge and Corboz-Warnery, 1999; León and Olhaberry, 2020). Communicative intentionality, therefore, is gradually co-constructed and integrated as part of the infant’s repertoire of skills, thanks to the adult-mediated encounters that take place over time (Rączaszek-Leonardi et al., 2019) and in which they often incorporate objects to communicate about—and through—the material world (Rodríguez, 2012).

Precisely, the lack of consideration given to objects in early interactions is another of the problems underlying their conceptualisation. From classical positions, triadic interactions with objects are based on episodes of joint attention, which can be understood from different perspectives (Gabouer and Bortfeld, 2021). On the one hand, from an associative perspective they would depend on the infant’s visual orientation system and its ability to follow the gaze of the other (Butterworth, 1991), which is considered to occur in the absence of interactive processes from six to 18 months of age (Butterworth and Jarrett, 1991; Corkum and Moore, 1998). On the other hand, from a social perspective, this highlights the coincidence of gazes between adults and infants on a referent (e.g., objects) in the framework of a dynamic interaction process that begins early in the first year of life (Striano and Stahl, 2005) but continues to develop throughout the second year (Tomasello and Farrar, 1986). Indeed, some studies emphasise the attentional, communicative, and co-regulatory processes between adults and infants in relation to an object of mutual interest, that unfold between 6 months and 1.5 years old. In this way, they distinguish between “coordinated joint engagement,” which refers to the multimodal components that occur in intersubjective episodes (e.g., smiles or gestures), and “passive joint engagement,” which would be limited to the coincidence of attentional focus on the same object (Bakeman and Adamson, 1984).

While the joint attention paradigm has occupied a central role in research over the last few decades, recent studies invite us to modify the analytical prism based on the growing interest in the multimodal components that underpin these adult-infant encounters (Yu and Smith, 2016, 2017). For example, adults tend to accompany episodes of joint attention by combining verbal input and tactile stimulation towards the infant (Suárez-Rivera et al., 2019). This could be associated with a longer duration of the infant’s gaze towards the object, compared to non-multimodal episodes. This evidence has called into question the study of joint attention as an isolated process, as it could be part of a conglomerate of cognitive, social, and communicative phenomena (Siposova and Carpenter, 2019; Jacobson and Degotardi, 2022) that take place in joint action dynamics between the infant and others (Reddy, 2005). In this sense, adopting an interactive and multimodal perspective would make it possible to emphasise not only attentional aspects but also other elements of the interaction such as emotion, touch, or use of objects (De Barbaro et al., 2013; Rossmanith et al., 2014; Moreno-Núñez et al., 2017).

The lack of an established consensus around triadic interactions, such as how and when they emerge, or the particular characteristics that arise from their conceptualisation has left an open theoretical and methodological debate. As such, there may be reason to identify those inconclusive areas and to explore the different perspectives on their origin, development, and nature of triadic interactions. To this end, we conducted a systematic and qualitative review that explored the scientific production of the last decades and its main findings, discussing their potential implications for the study of early development and early childhood education and care. In doing so, we can inform further empirical exploration of this phenomena.

Following the recommendations of the PRISMA 2020 statement (Page et al., 2021), an updated version of PRISMA 2009 (Moher et al., 2009), we conducted a comprehensive literature search in eight databases: Web of Science, Scopus, ProQuest, PubMed, ScienceDirect, PsycINFO, Dialnet, and Dimensions. To do so, we started with four keywords, in English and Spanish, which were combined with Boolean operators according to the following search equation: (“triadic interactions” OR “joint engagement”) AND object* AND child*. In addition to the articles recovered from the databases, other relevant studies, retrieved from the references cited in other research, were also included.

The PRISMA flow chart (Figure 1) illustrates the study selection process performed for this systematic review. The total number of results obtained in the initial search was 1,943 articles, of which 297 duplicates were eliminated. We then collected general information on each study (author, year of publication, title, source database and abstract) and reviewed their appropriateness to the study topic, based on the title and abstract. This resulted in the exclusion of 1,356 articles that were not related to our objectives, as they focussed, for example, on parental mental health, family interventions or research with non-human primates. From the resulting database (n = 290), full texts were analysed and screened according to the following eligibility criteria:

During the decision-making process, discrepancies regarding the inclusion of certain articles were resolved by consensus among the investigators. The screening process resulted in a final sample of 51 publications, which were subjected to a methodological quality analysis using QualSyst (Kmet et al., 2004). This tool provides checklists adapted to a wide range of methodologies and topics that allow the critical evaluation of qualitative and quantitative scientific papers. On this basis, it provides an estimate of the methodological quality of studies as a result of a score between 0 and 1, with 1 being the highest possible quality score. It also proposes different cut-off points for deciding on the exclusion of studies, ranging from 0.55 to 0.75. All the studies included in the final sample exceed the highest cut-off point of 0.75 (M = 0.925; SD = 0.06).

For the analysis, we first explored the distribution of the scientific production included in the sample in terms of its population characteristics (where the studies were carried out and the context in which the data were collected) and methodological characteristics (type of study, type of design, type of interaction task, and data analysis strategy). Secondly, we carried out a thematic analysis of the results, based on the discussion of findings related to the origin, development, and educational implications of triadic interactions.

The scientific literature on early social-communicative development has dealt extensively with the study of infants’ first triadic interactions with adults and objects, giving rise to different theoretical and methodological perspectives for their empirical study. The aim of this paper was to analyse some relevant issues on which there is still no consensus. To this end, recent scientific projects were explored, describing their methodological characteristics and discussing their results based on a thematic analysis. With respect to the distribution of the studies, we have been able to verify that most of the studies have been carried out in Western regions, mainly Europe and North America, thus reproducing a common bias in psychological research based on the study of WEIRD (Western, Educated, Industrialised, Rich, and Democratic) population samples. From a gender perspective, while this is not a study focused on gender disparities, it is striking that in most of the studies in our sample (except for those in which no details on gender were provided), adult data came from female participants, including mothers, educators, and researchers. Thus, to obtain a true picture of early socio-communicative development in everyday routines, it would be interesting for future research to explore the reasons behind this imbalance, as well as to promoting the participation of male adults in interaction studies with young children.

Moreover, the laboratory has been the predominant context for data collection, although there is a growing trend towards research in naturalistic contexts, such as the home. In this regard, technological advances in recent decades have led to the use of activity recording instruments that impact on the degree of ecological validity of the data. For example, some studies use head-mounted camera and eye-tracker systems to record infants’ field of vision and their visual trajectory during certain activities (Yu and Smith, 2013, 2016). However, we have not found studies that analyse triadic interactions by using wearable sensors, which could add accurate and relevant information about infants’ autonomy and/or motor activity when interacting in their environment (De Barbaro, 2019).

In relation to the methodological characteristics of the studies in our sample, there is a greater representation of descriptive studies as opposed to experimental designs, which are mainly longitudinal and cross-sectional. We consider this to be an important factor, especially at an early age, as longitudinal research allows for a better definition over time of the dynamic and changing processes related to the phenomena studied (Grimm et al., 2017). Finally, we have been able to observe how, in this sample, the use of quantitative strategies for data analysis prevails over qualitative or mixed methods approaches. Nonetheless, in qualitative studies, it should be noted that some of the techniques used could be particularly useful in the study of adult-infant interactions. For example, microgenetic procedures allow for in-depth and systematic analyses of the subtle changes that occur on a small scale in early development (Alessandroni et al., 2020; Lourenço et al., 2021). Furthermore, ethnographic studies such as that of Abels (2020), enrich observational data through researchers’ manual annotations during the continuous accompaniment of participants in their daily activities.

Subsequently, thematic analysis of the results has allowed us to identify different dilemmas about the nature of infants’ early experiences with adults and objects. First, research on joint attention and, specifically, on visual trajectories, has enabled us to approach the origins of adult-infant referential communication (Parise et al., 2007; Tremblay and Rovira, 2007; Perra and Gattis, 2012; Yu and Smith, 2013, 2016, 2017). Even when infants are limited by biological constrictions that prevent them from sustaining prolonged gaze, following the other’s gaze enables them to share references about the world (Flom et al., 2004; Cleveland and Striano, 2007; Osório et al., 2011).

Nonetheless, more recent work considers that joint attention goes beyond a simple coincidence of the gaze of two participants on the same object: during the interaction, they must also be attentive to the interlocutor’s behaviours and accommodate them, which implies understanding themselves and the other as intentional agents (Tomasello, 1995). For example, the adult takes advantage of the child’s bouts of attention to prolong exchanges by using various mediators, such as facial expression or language. This has led to an increasingly important role being given to exploration and communicative interaction, rethinking the study of phenomena associated with the beginnings of triadicity, based on the possibilities offered by materiality (Gibson, 1979). Accordingly, perception (attention) and action are part of the same process of active knowledge construction (Reddy, 2005; Heras Escribano, 2012). In this, attentional encounters would constitute the basis on which to establish instances of communication and joint action with others. These usually take place through objects and their cultural meanings (Moreno-Núñez et al., 2021b; Alessandroni, 2023), promoting learning that will gradually enable the child to operate coherently with the socio-material environment that surrounds them (Bruner, 1983; Rogoff, 1990; Carpenter et al., 1998).

This has led us to analyse other dilemmas surrounding the origin of the first triadic behaviours, such as when they emerge in the child’s development. In this regard, numerous studies agree that infants’ social-communicative skills become more sophisticated from the age of 9 months to a year (Trevarthen and Hubley, 1978; Tomasello et al., 2005), so a greater proportion of studies focussed on this period was expected (Flom et al., 2004; Parise et al., 2007; Osório et al., 2011; Mendive et al., 2013; Abels and Hutman, 2015; Abels, 2020). Despite this, it seems unlikely that infants’ communicative intentionality would suddenly emerge; on the contrary, it may emerge from early triadic encounters that adults organise around the object well before the age of 9 months (Striano and Bertin, 2005; Tremblay and Rovira, 2007).

Accordingly, the coordination of the processes necessary for triadic interaction would take place on the basis of the adult action (Amano et al., 2004; Cleveland and Striano, 2007) and infants’ early sensitivity to communicative cues, such as the exchange of glances at others and the object (Striano and Stahl, 2005). Consequently, before the infant can actively participate in triadic exchanges, the adult promotes their participation in a continuous process (Rodríguez and Moro, 1999) involving various semiotic mediators. On the one hand, they often resort to reiterative actions that favour the predictability of exchanges, making it easier for adults and infants to mutually “read” each other’s intentions over time (Alessandroni et al., 2020). On the other hand, adult mediation frequently relies on the use of objects and gives rise, as the infant acquires greater communicative tools, to actions which respond to the other’s behaviours and the cultural functionality of objects (Rossmanith et al., 2014; Moreno-Núñez et al., 2015, 2017; Cárdenas et al., 2020; Guevara et al., 2020).

Thus, aligned with a socio-constructivist and externalist approach to development, children build a shared “fund of knowledge,” which facilitates the learning of numerous skills (e.g., intentional understanding) and enables them to behave in a culturally situated manner (Barresi and Moore, 1996; Rochat, 2007; Brandone et al., 2019, 2020). Notwithstanding, these results must be considered in the light of some limitations. On the one hand, the underrepresentation of studies run in certain environments familiar to the child (e.g., nursery schools) and populations beyond the Western context, implies a bias that prevents extrapolation of some of the results. Future research aimed at a global understanding of early communicative processes (Amir and McAuliffe, 2020) should adopt an ecological perspective that responds to the everyday social, material, and cultural circumstances in which triadic interactions take place (Keller et al., 2009; Rowe and Goldin-Meadow, 2009; Abels, 2020).

Furthermore, the diversity of theoretical and conceptual interpretations of the origin and development of triadic interactions has made it necessary to adopt a qualitative approach in this review, aimed at describing and discussing the different positions. In contrast, a quantitative review (meta-analysis) would enable further exploration of some of the specific questions that arise from this study, such as the extent to which triadic interactions benefit early communicative development, or the relationship between different factors and children’s experiences of triadic interaction. For example, family socioeconomic status may be linked to different degrees of exposure to triadic interaction (Gago-Galvagno and Elgier, 2020), while atypical developmental trajectories (such as prematurity at birth, Down syndrome or high-risk for ASD) may result in difficulties over social participation (Chiang et al., 2008; Adamson et al., 2009; Benassi et al., 2016; Vilaseca et al., 2022) which can be improved through early intervention (Olafsen et al., 2006; Bejarano-Martín et al., 2022; Mattie and Fanta, 2023).

Further study of the development of early triadic interactions (i.e., from birth) could also provide possible improvements in early childhood education and care practises. For example, in the family context, some studies suggest that infants’ early communicative behaviours are not always effective in eliciting adult responses (Dimitrova et al., 2015; Boundy et al., 2016). Therefore, further exploration of infants’ cues in the context of early interactions around materiality could lead to the promotion of low-cost daily stimulation activities, such as shared reading practises (Black et al., 2017). This could also be relevant for exploring the impact of parental mental health in the development of early triadic interactions (e.g., in cases of postpartum depression or parental stress), as parental emotional regulation may affect their interactive and communicative styles (Apter and Devouche, 2019). In this sense, interventions aimed at accompanying parents by enhancing their interactive skills through video-feedback have been shown to boost caregivers’ self-perceived efficacy (Fisher et al., 2016) and contribute to improving parental mental health (Izett et al., 2021). In addition, they have also been shown to benefit infants’ development, for example, by fostering expressive and receptive communication skills (Imhof et al., 2023) or reducing behavioural problems (Liu et al., 2021).

Additionally, given the importance of the early years in psychological development and the importance of school as a socialising context, the findings synthesised in this review could be relevant for educators, as they could permeate educational processes to promote infants’ engagement with others and their environment. This requires further transferences between research and school, based on processes of joint reflection between professionals on their own educational practise. As is observed with parents at home, educators frequently mediate children’s participation in shared activities loaded with socio-cultural meanings and tools (Brossard, 2001; Rodríguez and De los Reyes, 2021). This takes place, again, through a multimodal prism in which objects, materials, language, gestures, and emotional expressions are usually involved (Estrada, 2021). Although these types of interactions are part of children’s everyday lives, it is surprising how little scientific literature to date has explored the educational practises at these early stages (0–3 years), particularly the role that material culture plays in shaping early development in various contexts.

The results of this review suggest that early triadic interactions: (1) are characterised as multimodal communicative exchanges that are structured in sequences of joint attention and action through materiality, (2) are built from the first months of life and develop thanks to adult mediation, and (3) constitute a privileged context for the construction of sociocultural meanings, which are fundamental for infants’ engagement with others and their environment.

A Spanish-language version of this article can be found online in the Supplementary material.

Publicly available datasets were analysed in this study. This data can be found here: https://doi.org/10.5281/zenodo.8134795.

AM-G: conceptualization, methodology, data curation, analysis, investigation, and writing – original draft. AM-N: conceptualization, writing – original draft, writing – review & editing, and supervision. All authors contributed to the article and approved the submitted version.

This study was supported by the Predoctoral Contract Scholarship for PhD Training (call 2020), granted to AM-G [reference PRE2020-094773], and project PID2019-108845GA-I00/AEI/10.13039/501100011033, both co-funded by the State Research Agency (Ministry of Science and Innovation, Spain) and the European Social Fund (ESF).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.