Use your words: The role of language in the development of toddlers’ self-regulation

Abstract

Self-regulation emerges throughout early childhood, and predicts later success in socially and cognitively challenging situations. Vygotsky proposed that symbols, particularly words, serve as mental tools to be used in service of self-regulation. Cross-sectional research indicates a positive but inconsistent association between language and self-regulation skills throughout toddlerhood, but research has not accounted for general cognitive development, nor gender differences in these domains. We used growth modeling of longitudinal data for 120 toddlers collected when children were 14, 24, and 36 months to test the impact of two expressive language skills – spoken vocabulary and talkativeness – on the growth of toddlers’ self-regulation, and to determine whether associations between these domains exist when controlling for cognitive development. Results reveal gender differences in self-regulation trajectories, and in the impact of language on self-regulation. Vocabulary is a better predictor of self-regulation than talkativeness, and both concurrent and prior vocabulary positively predicted children's levels of self-regulation. When cognitive development was controlled, 24-month vocabulary still predicted the trajectory of self-regulation. Results reveal that, even in early development, words are tools that can be applied to the task of self-regulation, and may be a more necessary tool for boys than for girls at this age.

Introduction

“Use your words” is a common phrase addressed to toddlers and preschoolers who are acting out in frustration. This phrase reveals the common belief that when children have the words to express their desires, needs, or feelings, they can better regulate their behavior to match the social expectations of the situation. The ability to self-regulate enables children to adapt to and gain the most from their environments; thus much attention is given to the developmental processes and experiences that help children develop self-regulation skills. Several studies have found positive associations between language skills and pro-social and self-regulatory behavior in 3–5-year-olds in both typical (e.g. Astington and Jenkins, 1999, Cutting and Dunn, 1999) and atypical populations (Cole et al., 1994, Spira and Fischel, 2005). However, few studies have examined such associations for children under three, when there is wide variation in language skills, and when developmentally based interventions may be most valuable. Cole, Armstrong, and Pemberton (2010) review the research on the development and integration of expressive language and self-regulation skills, and pose the question: do children need to develop a certain level of expressive language, executive functioning, and emotion regulation as separate domains before these skills are integrated? Thus, we may ask whether parents and educators have unrealistic expectations about the role of language in the self-regulatory skills of toddlers when they use the phrase “Use your words” to encourage a child's verbal self-regulatory skills. Do language skills support the self-regulation of even very young children, or do these skills integrate only later in development once children are more consistent users of language? Further, if language skills do support self-regulation, which aspects of language help children self-regulate? It might be that children who talk more exert more control over their environments and thus are less frustrated. Or it may be that children who have larger vocabularies, indicative of larger symbolic repertoires, have more mental tools to use in service of self-regulation. This paper addresses the commonly held belief that young children's language skills support their self-regulation by examining the longitudinal development of these skills in toddlers.

Self-regulation is widely recognized as a critical social-emotional skill underpinning children's abilities to act pro-socially with peers and adults, participate productively in learning activities, and adapt successfully to new or challenging situations. Kopp (1982) described the basic development of self-regulation in early childhood as growing from early reactive reflexes to proactive and conscious planning processes (Bronson, 2000, Kopp, 1982). In the toddler years, between 1 and 3 years of age, self-regulatory skills are still rudimentary, yet develop rapidly. In the first half of the second year, children gain awareness of social requirements and expectations and can initiate and terminate actions to comply with these expectations and to achieve social and physical goals. In the third year of life, children's growing representational skills underpin their ability to exert control on their own actions in response to internal representations such as rules, rather than just in reaction to a parent's immediate prohibitions or reminders (Kopp, 1982).

One source of variation in early self-regulation is gender. Weinberg and colleagues have documented that within the first year of life, girls show a greater diversity of self-regulatory strategies, and maintain their physiological regulation more consistently in the face of external challenges, such as mothers’ absence (Weinberg, Tronick, Cohn, & Olson, 1999). Further, Raikes and colleagues found that girls had higher self-regulation skills throughout toddlerhood between 14 and 36 months of age (Raikes, Robinson, Bradley, Raikes, & Ayoub, 2007). Another source of variation in young children's self-regulation is their general cognitive skills, particularly the development of executive functioning which, during early childhood, is particularly dependent upon brain maturation (e.g. Bernier et al., 2010, Stevens et al., 2009).

Vygotsky (1934/1986) proposed that self-regulation of thought and behavior is learned through a process in which children learn their culture's symbols and thought patterns by internalizing their caregivers’ regulatory speech. According to Vygotsky, internalized symbols – typically words – become mental tools to be used in service of manipulating one's own mind and behavior. Thus, we reason, the broader one's symbolic repertoire, the more tools for self-regulation one has. Kopp (1982; Vaughn, Kopp, & Krakow, 1984) frames the development of self-regulation similarly as an internalization of caregiver-modeled regulatory strategies. In early development, caregivers play a central role in regulating children's behavior and emotion using increasingly cognitive means—that is, by talking to them, providing verbal prohibitions or comforts (Vaughn, Kopp, & Krakow, 1984). Thus, the transition from reactive (e.g. self-soothing after upset) to proactive (e.g. inhibiting pre-potent behavior) regulation is facilitated by children's growing representational abilities, including the internalization of their caregivers’ self-regulatory speech facilitated by language development. If this is true for even very young children, we might expect their self-regulation skills to grow as their vocabulary grows rapidly in the second and third years of life.

There is a body of research linking self-regulation and language skills. Most of these studies have been conducted with preschool and older children (e.g. Müller et al., 2008, Ponitz et al., 2009). For example, Bono (2003) found an association between self-regulation and language development in children entering kindergarten, and found that self-regulation mediated the relationship between language and cognitive school readiness. Further, there are studies showing associations between delayed language and behavior problems. For example, observing preschool children with and without language delays in a classroom setting, Qi and Kaiser (2004) found that preschoolers with language delays more often acted aggressively and disruptively, and were less likely to initiate and engage pro-socially. Thus, as preschool children's representational repertoires grow, so do their abilities to regulate their behavior in the service of social expectations.

While these studies with older children provide support for the hypothesis that language supports self-regulation, as pointed out by Müller, Jacques, Brocki, and Zelazo (2009), most studies of these two domains either test non-directional associations between language and self-regulation, or use language as a control variable, rather than investigating the contribution of language to self-regulation (Müller et al., 2009). In the current study, we are interested in whether and how language supports the development of early self-regulation.

Evidence for a supportive relationship between language skills and self-regulation also comes from intervention studies. One intervention study by Lederer (2001) documented the effects of a language intervention for late-talking toddlers in the early third year of life. Though the intervention was focused on child vocabulary, parents reported increases in children's social as well as language skills. Another intervention aimed at increasing preschoolers’ language skills found that children's participation during preschool predicted their social skills in early adolescence (Niles, Reynolds, & Roe-Sepowitz, 2008). Specifically, the participants had lower acting out behaviors, higher assertiveness, and better social skills with peers. Importantly, these effects varied by gender and by family risk status. Participation in the language intervention had a greater impact on boys’ than girls’ acting out behavior, and children who came from higher-risk families – in terms of income, parental education, parental employment, and family structure – had greater gains in assertiveness and positive social behavior with peers (Niles et al., 2008).

Cole et al. (2010) propose several ways that expressive language may support self-regulation skills, even in young children. They propose that expressive language provides children with a socially acceptable way to communicate their needs, that language enhances children's abilities to understand internal states, and that language may also serve to help children regulate their own behavior (p. 59). One way that language skills have been documented to contribute to preschool children's self-regulatory abilities is through the use of private speech. While this evidence does not yet extend to children under 3 years old, it is useful to review it here to consider whether this may be one mechanism by which greater language skills may lead to greater self-regulation.

Self-regulatory private speech – or talking to one's self in order to monitor and modify one's own behavior – has been documented as early as the fourth year of life (Winsler, Carlton, & Barry, 2000). Private speech among preschool children predicts social skills such that children who use more private speech to solve problems have greater social skills and fewer problem behaviors (Winsler, De Leon, Wallace, Wilson-Quayle, & Carlton, 2003). Further, both boys’ and girls’ use of private speech during solitary activities has been associated with teacher-rated self-regulation skills (Broderick, 2001). Both children who are at risk for behavior problems, and those who are not, benefit from using private speech; and both groups increase their use of private speech and their subsequent performance on challenging motor tasks when instructed by a teacher to use speech (Winsler, Manfra, & Diaz, 2007). While the documentation of language used in the service of self-regulation – through private speech – is sparse for infants and toddlers under 3 years old, there is no published evidence that private speech does not occur prior to 3 years old. In fact, some work on gestures indicates that children in their second and third years of life can use gestures in a self-reflexive way to modify their own behavior (see Pea, 1980, Rodriguez and Palacios, 2007, Vallotton, 2008).

There are two cross-sectional studies that have addressed the relationship of language and self-regulation in children under 3 years old, both of which show positive associations between the domains. Vaughn et al. (1984) examined the developmental predictors of self-control during toddlerhood between 18 and 30 months of age. They measured self-control with a series of tasks testing the ability to delay or inhibit predominant responses and to comply with parents’ requests; they measured language and overall developmental age using the Gesell Scales (Knobloch & Pasamanick, 1974). They found that language development was correlated with self-control in the combined cross-age sample. However language was only related to one of the four self-control measures when age was partialled out. In the same study, the authors found that developmental quotient was correlated with three of four self-control composites (Vaughn et al., 1984), but the authors did not report testing the association between language and self-control when either age or developmental quotient was controlled. Comparison of the different correlations in this study between language and self-control across ages showed that while language skill was not associated with self-control at 18 months, the skills were positively associated at 24 months. The authors stated that the small sample size at 30 months (n = 19) did not allow the authors to determine the relationship at that age. Thus, it is possible that the relationship between language and self-control changes through early development, or that a consistent relationship might be seen with a larger sample. The cross-sectional design of this study limited it to correlational associations and did not allow the authors to test whether earlier language skills might support later self-control.

Cournoyer, Solomon, and Trudel (1998) examined the relationship between language and self-control in two groups of toddlers, 18-month-olds and 24-month-olds. They tested age and sex differences in both developmental domains, and the relationship between the domains at each age. They found that girls had higher self-control and higher language skills at both ages. Similar to the findings of Vaughn et al. (1984), as reviewed above, they also found that language skills and self-control were positively correlated at 24 months, but not at 18 months (Cournoyer et al., 1998).

Though these studies provide convergent evidence on the positive relationship between language abilities and self-regulation skills during toddlerhood, they share several limitations. Both studies are cross sectional and do not allow for a test of the effect of earlier language skills on later development of self-regulation; thus, they both test non-directional associations between the domains. With null results due to small sample sizes at 18 and 30 months, these studies leave uncertain the strength and stability of the relations between domains across early childhood, particularly the relation between language and self-regulation when developmental timing or general cognitive ability is taken into account. Further, though gender differences in both domains are noted by Cournoyer et al. (1998), they do not report testing whether the relationship between the domains may be different for boys and girls, nor whether the gender differences in one domain may be explained by gender differences in the other. Finally, both studies used very general assessments of language ability, rather than assessing specific aspects of language skills. As proposed by Cole and colleagues (2010), it may be the expressive aspects of language that are most useful as tools for children's self-regulation.

The studies reviewed above provide convergent evidence for the positive association between language and self-regulation in preschool and older children, and preliminary evidence for the same association in very young children, those under 3 years of age. However, in order to test the unique role of language in self-regulation in early childhood, both age and general cognitive development must be taken into account. Further, to determine whether there is a truly supportive relationship between language and self-regulation in early childhood, as suggested by Vygotsky's theory, a longitudinal study involving repeated measures of the development of language, self-regulation, and general cognitive development is needed in order to test whether earlier language skills predict later self-regulation controlling for the contribution of concurrent language skills.

The negative effects of poverty, and its associated risks, on child development are far-reaching, impacting both self-regulation (Raver, 2004) and vocabulary (Hoff, 2006). Research demonstrates that although poor children perform near national norms on standardized tests in infancy, as a group, their scores are significantly lower than national norms by the preschool years in language (Hart & Risley, 1995) and in cognitive skills more generally (Ayoub et al., 2009, Black et al., 2000). This negative association between poverty and development, specifically verbal language skills, exists across cultures and persists throughout the school years (Bradley and Corwyn, 2002, Farkas and Beron, 2004). Further, this gap between children growing up in poverty and those with higher socio-economic status can be linked to parents’ language and communicative behaviors in their interactions with their children; the richness of parents’ language used with children, including spoken vocabulary, predicts children's growth in spoken vocabulary (Hoff, 2003, Rowe and Goldin-Meadow, 2009). Thus, family poverty and the influential differences in parent-child interaction associated with poverty form an important context in which to examine the development of children's language skills, and the effects of those skills on other domains.

The current study extends Vygotksy's theory regarding words as mental tools into very early childhood, testing whether there is a supportive relationship between language skills and self-regulation in children who are just learning to use language. We analyze a dataset from a three-wave longitudinal design covering the period of first language learning, including measures at 14 months when inter-individual variation in language and communication skills begin to emerge, 24 months when variation in children's early language skills is at its greatest, and 36 months when typically developing children have some expressive language and the individual variation in vocabulary has decreased (Fenson et al., 1994). Substantial individual differences in language development emerge around age two and predict vocabulary size around 5 years of age (Hart & Risley, 1995); thus, we are particularly interested in how language skills at 2 years are related to self-regulation. The data were originally collected as part of the National Early Head Start Evaluation Study (Administration for Children & Families, 2002).

Among the many aspects of language rapidly developing during early childhood (e.g. Pan et al., 2005, Reich, 1986), we focus on two aspects of expressive language: talkativeness, as indicated by the total number of word tokens children speak during a given time, and spoken vocabulary, as indicated by the number of unique vocabulary words children speak during a given time. Contrasting these two aspects of expressive language allows us to test whether it is children's frequent use of language to express themselves and get their needs met that results in less frustration and thus less need to regulate their behavior; or whether self-regulation is related to children's growing vocabulary which gives them more mental tools to manipulate their own thoughts, emotions, and behavior.

The current study tests whether children's talkativeness (word tokens) and spoken vocabulary (unique vocabulary words) are associated with self-regulation during toddlerhood, from 1 to 3 years old. We test whether the data are consistent with the hypothesis that self-regulation is influenced by children's language skills, by determining whether language at 2 years old predicts the trajectory of self-regulation, when accounting for concurrent language skills. Further, given the average gender differences in the timing of language development for very young children (Fenson et al., 1994, Huttenlocher et al., 1991), and preliminary evidence that there are gender differences in self-regulation during toddlerhood (Raikes et al., 2007), we test whether a gender difference in the trajectory of self-regulation is explained by a gender difference in language. Finally, we test whether the association between children's language and self-regulation skills is explained by their overall cognitive development, or whether language contributes something unique to children's self-regulation skills over and above general cognitive development. We address the following questions:

• Which child language skills – talkativeness or spoken vocabulary – if either, support the development of self-regulation between 14 and 36 months of age?

• Do talkativeness and spoken vocabulary account for the gender differences in self-regulation from 14 to 36 months of age?

• Is the relationship between these expressive language skills and self-regulation explained by general cognitive development?