Hypothesis 1—Changes in Maternal Responsiveness Behaviors
The findings of this experimental study demonstrate that the PALS interventions influenced higher levels and/or increases in maternal responsiveness across three behaviors from an affective emotional style (contingent responsiveness, warm sensitivity, positive affect) and two behaviors from a cognitively responsive style (attention to child focus of attention, rich verbal input). However, determination of the optimal timing of PALS (only early, only later, early and later) for responsiveness depended on factors such as the type of support a behavior provided to a child and the child’s biological risk status. Responsiveness behaviors best facilitated by PALS I tended to be those that provided warmth and nurturance, whether or not mothers also received the intervention during the toddler–preschool period. Warmth is described in the attachment framework as critically important across the first year of life for establishing a secure and trusting relationship between a mother and her infant (e.g., Ainsworth et al., 1978
). When high levels of warm sensitivity occur across this early period, a lasting positive influence on multiple aspects of the child’s development is hypothesized. Our results suggest that there is a unique salience about the early developmental period for an intervention to support mothers’ expressions of warmth that extends beyond the first year of life.
The unique salience of the early developmental period for maternal behaviors from an attachment framework was particularly apparent for mothers of children born at VLBW. Although mothers of term and VLBW children who received PALS I showed higher levels of warmth than mothers receiving DAS I, only mothers of the VLBW children who received PALS during infancy showed faster rates of increases. This same unique PALS I effect for mothers of VLBW children also was apparent for mothers’ increases in the expression of positive affect. Positive affect indicates pleasure in a mother’s relationship with her infant and is another responsiveness behavior described in the attachment framework as critically important during the first year of life. One focus of PALS I was to help mothers appreciate and receive pleasure in their infants’ efforts. This focus may be particularly helpful for mothers of children at VLBW because of the greater vulnerability of VLBW infants for difficulty learning new behaviors and their mothers’ greater concerns about their development. A facilitator assisting mothers in this early period to respond sensitively to their infants’ needs and to take pleasure in their attempts to interact appears to promote a greater bond and acceptance of their child’s behavior in spite of their child’s risk status.
Contingent responsiveness is a more complex behavior than warmth and positive affect, as it requires the caregiver to notice and respond to the child’s signals promptly, sensitively, and contingently related to what the child signaled. Thus, a parent needs to appreciate the child as an individual with needs and requests that may be different from those of the parent. Contingent responsiveness was significantly influenced by the intervention but required PALS at both the early and later periods for mothers of all children to show the optimal levels. We expected that the demands of the toddler–preschool child would make it more difficult for mothers to attend consistently to the child’s signals in a contingent manner. Thus, PALS II was expected to support mothers in adapting to the child’s changing needs rather than seeing them as more demanding, and this hypothesis was supported. This finding suggests that when designing parent responsiveness interventions for the toddler–preschool period, behaviors that require mothers to adjust a great deal to their children’s changing developmental needs should receive more attention than those that provide more basic nurturance.
Support of children’s attentional focus through maintaining rather than redirecting was an additional aspect of responsiveness targeted by PALS. Sociocultural frameworks highlight the specialized scaffolding that maintaining provides for young children’s immature cognitive and attention skills, in contrast to the greater demands that redirecting places on them (Tomasello & Farrar, 1986
). Higher levels of maintaining were found for mothers who received PALS I as compared to those who received DAS I. However, avoidance of redirecting was best facilitated if mothers in both risk groups received PALS during both developmental periods. Similar to contingent responsiveness, avoidance of redirecting requires a caregiver to carefully monitor and respond to a child’s signals, but the focus is on attending to signals involving the child’s interest in objects and activities. Thus, it may be that a second “dose” is needed to sustain lower levels and faster decreases in this intrusive interactive behavior across a time when children are increasing their exploratory activities and their need for caregivers’ attention to their interests.
Mothers’ quality of language input (i.e., verbal scaffolding and encouragement) was impacted mainly by participation in PALS II. Provision of verbal input such as (a) providing labels and explanations and (b) highlighting links between objects and actions was best supported for mothers receiving the intervention during the later developmental period. The faster rates of gain in verbal scaffolding, however, were seen for mothers of term born children and not for those parenting children born at greater biological risk. Verbal scaffolding requires mothers to adapt and alter their behaviors to match their children’s gestural and verbal signals and to provide verbal input that is aligned with and supports the child’s level of understanding and use of words. The advantage of PALS II for mothers of term born children may be best understood by considering the term children’s more mature levels of communication and signals that they provide for their mothers. This, in turn, allows mothers greater opportunities to use the verbal scaffolding techniques they have been facilitated to learn through the PALS II intervention. It may be that as the children born VLBW reach higher levels of communication skills, their mothers with PALS support will begin to respond with this type of rich verbal input.
Higher levels of verbal encouragement also occurred if mothers received the intervention at least during the later developmental period, but the benefit of PALS II was seen for mothers of term and VLBW children. As children are more active and independently engaged with their environments as toddlers and preschoolers, PALS facilitated mothers to respond positively to this engagement with positive encouragement. Thus, the importance of PALS II for mothers’ use of this form of verbal input may be due to greater opportunities for it to occur as children increased in age. Exposure to PALS during the early period also supported mothers of term children to use more verbal encouragement. Again, the specific developmental needs of the child may help researchers understand these findings. Term born children may have been more developmentally ready in infancy for this form of responsive verbal input, while those born at VLBW became ready later.
Hypothesis 2—Effects on Child Outcomes
Communication and social behaviors with mothers
As with the findings for mothers’ behaviors, the optimal timing of the intervention for children’s development was dependent, in part, on the skill complexity and the age at which the skills would naturally be emerging. Intervention effects were found for all language and social areas, but the timing varied depending on the skill being assessed. For example, greater use of multiword utterances, a skill that begins in the toddler period, was best facilitated when mothers received PALS II, and this was found for children in both risk groups. One of the more complicated outcomes examined was word use in combination with coordination of joint attention. For children to show better development of this more complex communication skill, their mothers needed to receive multiple doses of the intervention, and only the term born children of mothers receiving both PALS interventions showed the higher levels and greatest increases in this behavior. Joint attention skills begin to develop across the first year of life and are supported by responsive interactive behaviors such as maintaining versus redirecting infants’ attentional focus (e.g., Akhtar et al., 1991
). Coordinating this behavior with word use develops later. Such coordination may benefit from both intervention phases because mothers initially learn to engage their children with objects and activities, and later build on this foundation by requesting verbalizations from their child during joint attention activities.
Children’s social development was impacted by the interventions in similar ways for children born term and those born at VLBW. Cooperation and social engagement were at higher levels for all children when their mothers had received PALS II. An additional benefit for greater increases in social engagement was found for those whose mothers received PALS I, suggesting that for children to develop a range of social skills, PALS I and II were required. Given the challenges of guiding toddlers’ behavior and the need to avoid highly punitive discipline to facilitate development, PALS II included one session specifically focused on strategies to help children cooperate (e.g., giving choices, praising positive behaviors while ignoring negative behaviors). However, the positive effect of PALS II on children’s cooperation was unlikely due to this session alone but rather to the curriculum’s general focus on parent–child engagement and responsiveness to children’s signals. This is consistent with other studies demonstrating that toddlers are more motivated to cooperate with highly engaged and responsive parents (Parpal & Maccoby, 1985
). The need for both interventions for optimal social engagement indicates an additive effect, such that the later intervention promoted higher skill levels, but the early intervention supported greater increases. As social skills begin to develop in infancy, mothers who were facilitated to show greater warmth and responsiveness in early interactions seem to be laying a foundation for their children’s social development. Children’s skills, in turn, were further facilitated as mothers continued to learn effective responsive behaviors across the toddler–preschool period.
Effect on children’s standardized language scores
The strength of the intervention results are enhanced by the effects on standardized assessments of language development in addition to children’s use of language and social skills when interacting with their mothers. In general, PALS II was most important for the development of vocabulary for all children. Although children of mothers who received DAS were showing faster rates of increase, the children whose mothers received PALS II had the highest levels of vocabulary at the posttest. PALS II also was most influential for composite language skills, but this advantage was only seen for term born children. These results demonstrate that the influence of mothers’ responsiveness on children’s development extends to children’s language competence in situations quite removed from interacting with their mothers. As language skills in the preschool period are one of the three critical predictors of school-age reading competence (National Institute for Literacy, 2006
), this finding suggests that one approach to supporting early literacy is through a parent responsiveness intervention that targets the use of rich language input.
Mediation of Intervention Effects
The use of a randomized design provides evidence that changes in children’s behavior were due to changes in their mothers’ behavior. Further support for this was found in analyses demonstrating that the influence of the intervention on children’s outcomes was mediated by changes in parenting behaviors. Mediation effects emerged for the impact of the intervention on all of the children’s social skills (i.e., cooperation, social engagement, affect). Models showed that warm sensitivity was a significant mediator of all three social behaviors and that contingent responsiveness was a mediator for children’s gains in cooperation and social engagement. Both of these maternal behaviors are described from an attachment framework as critically important aspects of a caregiver’s affective–emotional style that should explain children’s ability to develop social and emotional competence (e.g., Bornstein & Tamis-LeMonda, 1989
The avoidance of redirecting children’s attentional interests was also important for their social competence as it mediated the intervention effect on social engagement. Redirecting is often associated with a sociocultural theoretical framework as avoidance of this strategy provides specialized support for children’s immature attentional skills. For children to be socially engaged, they need to attend to the cues of others and mothers’ avoidance of redirecting appears to support their ability to use their attentional resources.
The importance of contingent responsiveness as a mediator of the effect of the intervention also was seen for children’s language development. This was found for word use, coordination of attention with use of words, and standardized vocabulary scores. Other mediators of gains in language development were mothers’ avoidance of redirecting, their warmth, and for children born at VLBW, mothers’ positive affect. Thus, as with social competence, mothers’ expression of warmth, pleasure, and responsiveness to signals help explain how the intervention supported young children’s language development. It is not clear why mothers’ verbal input (e.g., verbal scaffolding and encouragement) was not a mediator of language development. As verbal scaffolding only showed intervention effects for mothers of term born children, the impact of this verbal strategy may not have been strong enough to influence gains in language. Also, high ratings of contingent responsiveness in our coding system included promptness and appropriateness of mothers’ reactions to child signals with “reactions” being characterized, in part, by language input that was sensitively responsive. Thus, the strong influence of contingent responsiveness on language skills goes beyond providing language input to also include the manner in which the input is provided.
Our findings provide implications regarding the optimal timing of interventions for promoting maternal responsiveness and, in turn, children’s social and communication development. Optimal timing was found to depend, in large part, on the specific targeted behavior and on the degree to which the behaviors were linked to a child’s changing developmental needs. These results provide support for the causal influence on children’s development of a responsive style that includes behaviors from attachment and sociocultural frameworks. The benefit of this integrated approach was highlighted by the mediation models, where behaviors such as contingent responsiveness and warmth, together with support for children’s attention skills, provided the best explanation of the intervention’s effect on both social and communication skills. Finally, the intervention effects on maternal and child behaviors showed many similarities for mothers of children term born and VLBW. However, mothers with VLBW children received a particular benefit of the early intervention for warmth and pleasure with their infants. This may have occurred as these infants are more developmentally vulnerable in infancy and behaviors such as warmth facilitate a bond between a mother and infant that, in turn, supports the infant’s early development. In contrast, when mothers of term born children received an added benefit of the intervention, it was in the area of rich language input, a scaffolding behavior often associated with the sociocultural framework. The particular benefit of the intervention for these mothers’ rich language input may be due, in part, to a greater developmental readiness of the term born children for verbal stimulation. Positive effects on children’s social and language outcomes generally were the same across risk groups with a few exceptions that showed a greater benefit for those children born term (e.g., composite language skills). Also, as groups were balanced with respect to ethnicity and primary home language, results indicate that the interventions were effective for families with a range of characteristics.
Limitations of the present study include the extent to which the results would generalize to parents from a broader economic range, given that study families were lower middle and lower socioeconomic status. While infants born VLBW were included as the higher risk group, it is not known if results would generalize to other infant groups who are known to have developmental problems (e.g., Spina Bifida, Down’s Syndrome). In addition, the extent to which positive gains in maternal responsiveness behaviors and children’s outcomes persist beyond the 3-month follow-up period remains a question.
The findings have logistically important and clinically meaningful implications for decisions regarding bringing parenting interventions to a larger scale. First, they demonstrate that if a parent intervention is only implemented in the infancy or the toddler–preschool period, the facilitation of some aspects of parent responsiveness and child social and communication development will be compromised. Second, the findings can provide guidance for determining the scope of an early versus later intervention in order to maximize the effectiveness of each phase for supporting a comprehensive responsiveness style. A natural next step would be to design and evaluate the combined influence of a staged curriculum model that begins with intervention sessions during the infancy period and strongly focuses on aspects of warmth and contingent responsiveness (i.e., maintaining attention and interpreting signals). A second stage during toddlerhood would then build on this supportive foundation with targeted emphasis on rich language stimulation, using responsive behaviors to promote cooperation and independence, and modifying expectations to adapt to children’s changing needs. It also would be valuable to determine the extent to which the positive effects of the PALS curriculum extend into childhood, and whether additional intervention “boosters” beyond the toddler–early preschool period would enhance these effects.