Lorenz's classic 'baby schema': a useful biological concept?

Konrad Lorenz introduced the concept of a 'baby schema', suggesting that infants have specific physical features, such as a relatively large head, large eyes and protruding cheeks, which function as an innate releaser to promote caretaking motivation from perceivers. Over the years, a large body of research has been conducted on the baby schema. However, there are two critical problems underpinning the current literature. First, the term 'baby schema' lacks consistency among researchers. Some researchers use the term baby schema to refer to infant stimuli (often faces) in comparison with adults (categorical usage), while others use the term to refer to the extent that features contribute to cuteness perception (spectrum usage). Second, cross-species continuity of the 'baby schema' has been assumed despite few empirical demonstrations. The evolutionary and comparative relevance of the concept is, therefore, debatable, and we cannot exclude the possibility that extreme sensitivity to the baby schema is a uniquely human trait. This article critically reviews the state of the existing literature and evaluates the significance of the baby schema from an evolutionary perspective.

Caregiver greeting to infants under 6 months already reflects emerging differences in those later diagnosed with autism.

As infants develop, caregivers adjust their behaviour to scaffold their infant's emerging skills, such that changes in infants' social abilities are expected to elicit changes in caregiver behaviour. We examined whether changes in the probability of infant-directed caregiving behaviour-specifically, greeting, a ubiquitous signal used by caregivers to initiate reciprocal interactions-differ between infant-caregiver dyads with an infant later diagnosed with autism and dyads with a neurotypically developing infant during infants' first 6 months. Using longitudinal data from 163 dyads, we found that caregivers in autism dyads (n = 40) used greeting less and at later infant ages than caregivers with a neurotypically developing infant (neurotypical dyads, n = 83). Caregivers in dyads with infants at elevated familial genetic likelihood for autism who did not receive an autism diagnosis (EL-non-autism dyads, n = 40) showed no differences in greeting compared with neurotypical dyads. Socioeconomic status partially mediated the difference between autism and neurotypical dyads. These findings show that autism and socioeconomic status were associated with the mutually adapted dynamics of dyadic interaction beginning in the first postnatal weeks. Importantly, differences in caregiver greeting observed in autism dyads are not interpreted as suboptimal behaviour from caregivers but rather indicate how early emerging social differences related to autism, years before overt features are present, may alter social learning opportunities elicited by the infant.

Mother-infant interaction characteristics associate with infant falling reactivity and child peer problems at pre-school age.

This longitudinal study investigated the associations between mother-infant interaction characteristics at 9 months of age, maternal mental health, infant temperament in the first year postpartum, and child behaviour at 3 years of age. The infants (N = 54, 22 females) mainly had White British ethnic backgrounds (85.7%). Results showed that i) mother-infant dyadic affective mutuality positively correlated with infant falling reactivity, suggesting that better infant regulatory skills are associated with the dyad's ability to share and understand each other's emotions; and ii) maternal respect for infant autonomy predicted fewer child peer problems at 3 years of age, suggesting that maternal respect for the validity of the infant's individuality promotes better social and emotional development in early childhood.

Early Play Behaviors of Infants at Elevated Likelihood for Autism Spectrum Disorder.

IMPORTANCE: Although research has examined early identification of autism spectrum disorder (ASD), few studies have found behavioral markers during midinfancy associated with later ASD diagnosis. OBJECTIVE: To examine infants' play behaviors and atypical positions at age 6 mo and later outcome classification among infants at elevated likelihood (EL) and typical likelihood (TL) for ASD. Atypical positions refer to movement patterns indicative of motor delays or deviations, including atypical extension and flexion, poor weight shift and rotation, hypertonicity or hypotonicity, and the presence of primitive reflex patterns. DESIGN: Observational cohort longitudinal design using blinded video analysis. PARTICIPANTS: Fifty-eight infants (41 EL infants and 17 TL infants) 6 mo of age. RESULTS: Infants later diagnosed with ASD needed more support to engage in play at age 6 mo compared with infants who did not receive an ASD diagnosis (U = 130, z = -2.29, p < .05, r = .31). Atypical positions at 6 mo of age were not associated with a later diagnosis of ASD. CONCLUSIONS AND RELEVANCE: Play behaviors may be early indicators of developmental differences for infants later diagnosed with ASD. The results of this pilot study suggest the need to observe the quality of interaction with a caregiver and objects during early play, which may serve as potential early indicators of ASD. Plain-Language Summary: Few studies have found behavioral markers during midinfancy that are associated with a later diagnosis of autism spectrum disorder (ASD). The results of this study showed that infants who were later diagnosed with ASD were found to have differences in play behaviors compared to infants who were not later diagnosed with ASD. Thus, early play behaviors may be an early indicator of developmental differences for infants who are later diagnosed with ASD.

Infant Behaviors, Prenatal Cocaine Exposure, and Adult Intelligence.

Importance: Linking prenatal drug exposures to both infant behavior and adult cognitive outcomes may improve early interventions. Objective: To assess whether neonatal physical, neurobehavioral, and infant cognitive measures mediate the association between prenatal cocaine exposure (PCE) and adult perceptual reasoning IQ. Design, Setting, and Participants: This study used data from a longitudinal, prospective birth cohort study with follow-up from 1994 to 2018 until offspring were 21 years post partum. A total of 384 (196 PCE and 188 not exposed to cocaine [NCE]) infants and mothers were screened for cocaine or polydrug use. Structural equation modeling was performed from June to November 2023. Exposures: Prenatal exposures to cocaine, alcohol, marijuana, and tobacco assessed through urine and meconium analyses and maternal self-report. Main Outcomes and Measures: Head circumference, neurobehavioral assessment, Bayley Scales of Infant Development, Fagan Test of Infant Intelligence score, Wechsler Perceptual Reasoning IQ, Home Observation for Measurement of the Environment (HOME) score, and blood lead level. Results: Among the 384 mothers in the study, the mean (SD) age at delivery was 27.7 (5.3) years (range, 18-41 years), 375 of 383 received public assistance (97.9%) and 336 were unmarried (87.5%). Birth head circumference (standardized estimate for specific path association, -0.05, SE = 0.02; P = .02) and 1-year Bayley Mental Development Index (MDI) (standardized estimate for total of the specific path association, -0.05, SE = 0.02; P = .03) mediated the association of PCE with Wechsler Perceptual Reasoning IQ, controlling for HOME score and other substance exposures. Abnormal results on the neurobehavioral assessment were associated with birth head circumference (ß = -0.20, SE = 0.08; P = .01). Bayley Psychomotor Index (ß = 0.39, SE = 0.05; P < .001) and Fagan Test of Infant Intelligence score (ß = 0.16, SE = 0.06; P = .01) at 6.5 months correlated with MDI at 12 months. Conclusions and Relevance: In this cohort study, a negative association of PCE with adult perceptual reasoning IQ was mediated by early physical and behavioral differences, after controlling for other drug and environmental factors. Development of infant behavioral assessments to identify sequelae of prenatal teratogens early in life may improve long-term outcomes and public health awareness.

Caregiver reactions to babbling organize turn-taking interactions: Facilitative effects of vocal versus non-vocal responses.

Turn-taking interactions are foundational to the development of social, communicative, and cognitive skills. In infants, vocal turn-taking experience is predictive of infants' socioemotional and language development. However, different forms of turn-taking interactions may have different effects on infant vocalizing. It is presently unknown how caregiver vocal, non-vocal and multimodal responses to infant vocalizations compare in extending caregiver-infant vocal turn-taking bouts. In bouts that begin with an infant vocalization, responses that maintain versus change the communicative modality may differentially affect the likelihood of further infant vocalizing. No studies have examined how caregiver response modalities that either matched or differed from the infant acoustic (vocal) modality might affect the temporal structure of vocal turn-taking beyond the initial serve-and-return exchanges. We video-recorded free-play sessions of 51 caregivers with their 9-month-old infants. Caregivers responded to babbling most often with vocalizations. In turn, caregiver vocal responses were significantly more likely to elicit subsequent infant babbling. Bouts following an initial caregiver vocal response contained significantly more turns than those following a non-vocal or multimodal response. Thus prelinguistic turn-taking is sensitive to the modality of caregivers' responses. Future research should investigate if such sensitivity is grounded in attentional constraints, which may influence the structure of turn-taking interactions.

Background TV and infant-family interactions: Insights from home observations.

Background television has been found to negatively impact children's language development and self-regulatory skills, possibly due to decreased parent-child interactions. Most of the research on the relationship between background TV and caregiver-child interactions has been conducted in laboratory settings. In the current study, we conducted home observations and investigated whether infants engage in fewer interactions with family members in homes where background TV is more prevalent. We observed 32 infants at the ages of 8, 10, and 18 months in their home environments, coding for dyadic interactions (e.g., parent talking to and/or engaging with the child), triadic interactions (e.g., parent and infant play with a toy together), and infants' individual activities. Our findings revealed that background TV was negatively associated with the time infants spent in triadic interactions, positively associated with time spent engaging in individual activities, and not significantly related to the time spent in dyadic interactions. Apart from the relationship between background TV and individual activity time at 8 months, these associations remained significant even after accounting for families' socioeconomic status. These findings imply a correlation between background TV exposure and caregiver-infant-object interactions, warranting a longitudinal analysis with larger sample sizes.

Neurobehavioral outcomes of infants exposed to buprenorphine-naloxone compared with naltrexone during pregnancy.

BACKGROUND: Naltrexone is a medication used to treat both opioid and alcohol use disorder with limited experience in pregnant individuals, particularly in comparison to more commonly utilized treatments such as buprenorphine-naloxone. The long-term outcomes of infants exposed to naltrexone has not been previously examined. AIMS: To compare the neurobehavioral outcomes of naltrexone versus buprenorphine-naloxone exposed infants. STUDY DESIGN: Multi-centered prospective cohort study. SUBJECTS: Pregnant people on prescribed buprenorphine-naloxone or naltrexone were enrolled during pregnancy and the dyad followed until 12 months after delivery. OUTCOME MEASURES: Infants were evaluated at 4-6 weeks corrected gestational age (CGA) using the NICU Neonatal Neurobehavioral Scale (NNNS) and at the 12-month CGA visit using the Ages and Stages Questionnaire, Third Edition (ASQ-3). RESULTS: There were 7 dyads in the naltrexone group and 34 in the buprenorphine-naloxone group. On the NNNS, infants exposed to naltrexone had higher median scores for arousal and excitability, and lower median scores for attention and regulation at 4-6 weeks CGA compared to the buprenorphine-naloxone group. None of the infants in the naltrexone group were monitored for NOWS and had shorter length of hospital stay compared with the buprenorphine-naloxone group. Although no statistically significant differences were observed, more infants in the buprenorphine-naloxone group were identified as at risk for development delays in the communication, problem solving, and personal social domains of the ASQ-3 at 12 months CGA. Results should be interpreted with caution given this study's small sample size and lack of a prospective comparison cohort. CONCLUSIONS: In this small cohort, there are differences noted in infant neurobehavior by NNNS at 4-6 weeks of age when comparing the buprenorphine-naloxone and naltrexone groups. At 12 months, ASQ-3 scores were similar but with percentage differences in potential development delay risk observed between the two groups. Larger cohort studies are needed to determine the long-term child outcomes after naltrexone exposure in pregnancy.

Neonatal neurobehavior associated with developmental changes from age 2 to 3 in very preterm infants.

OBJECTIVE: Understand how high-risk infants' development changes over time. Examine whether NICU Network Neurobehavioral Scale (NNNS) profiles are associated with decrements in developmental outcomes between ages 2 and 3 years in infants born very preterm. STUDY DESIGN: The Neonatal Outcomes for Very preterm Infants (NOVI) cohort is a multisite prospective study of 704 preterm infants born <30 weeks' gestation across nine university and VON affiliated NICUs. Data included infant neurobehavior measured by NNNS profiles at NICU discharge and the Bayley Scales of Infant and Toddler Development (BSID-III) at ages 2 and 3 years. Generalized estimating equations tested associations between NNNS profiles and BSID-III composite score changes between ages 2 and 3 years. RESULTS: The final study sample included 433 infants with mean gestational age of 27 weeks at birth. Infants with dysregulated NNNS profiles were more likely to have decreases in BSID-III Cognitive (OR = 2.66) and Language scores (OR = 2.53) from age 2 to 3 years compared to infants with more well-regulated neurobehavioral NNNS profiles. Further, infants with more well-regulated NNNS profiles were more likely to have increases in BSID-III Cognitive scores (OR = 2.03), rather than no change, compared to infants with dysregulated NNNS profiles. CONCLUSIONS AND RELEVANCE: Prior to NICU discharge, NNNS neurobehavioral profiles identified infants at increased risk for developing later language and cognitive challenges. Findings suggests that neonatal neurobehavior provides a unique, clinically significant contribution to the evaluation of very preterm infants to inform treatment planning for the most vulnerable.

Infant attachment does not depend on neonatal amygdala and hippocampal structure and connectivity.

Infant attachment is an antecedent of later socioemotional abilities, which can be adversely affected by preterm birth. The structural integrity of amygdalae and hippocampi may subserve attachment in infancy. We aimed to investigate associations between neonatal amygdalae and hippocampi structure and their whole-brain connections and attachment behaviours at nine months of age in a sample of infants enriched for preterm birth. In 133 neonates (median gestational age 32 weeks, range 22.14-42.14), we calculated measures of amygdala and hippocampal structure (volume, fractional anisotropy, mean diffusivity, neurite dispersion index, orientation dispersion index) and structural connectivity, and coded attachment behaviours (distress, fretfulness, attentiveness to caregiver) from responses to the Still-Face Paradigm at nine months. After multiple comparisons correction, there were no significant associations between neonatal amygdala or hippocampal structure and structural connectivity and attachment behaviours: standardised ß values - 0.23 to 0.18, adjusted p-values > 0.40. Findings indicate that the neural basis of infant attachment in term and preterm infants is not contingent on the structure or connectivity of the amygdalae and hippocampi in the neonatal period, which implies that it is more widely distributed in early life and or that network specialisation takes place in the months after hospital discharge.

Masked or not, I smile to you: Exploring full-term and preterm infants' social smiles to adults wearing a protective facemask.

The early emergence of social smiles is an important milestone of infants' socio-emotional development. Our aim was to assess how the use of protective facemasks by adults affects the display of social smiles in preterm (PT) and full-term (FT) infants at 3 months (corrected age for prematurity). We enrolled 30 FT and 30 PT infants (gestational age ≤ 32 weeks). Infants' social smiles displays were assessed at 2-3-month-age (corrected) across a three-episode (masked mother; unmasked mother; masked adult female stranger) videotaped interactive task. During each episode, the adult was instructed to maintain specific facial expressions (happy-smiling, sad-frowning, neutral-unresponsive) for 15 second windows and then instructed to interact spontaneously for 45 s (of which the first 15 s were coded). FT and PT infants did not differ in the display of social smiles. In both groups, social smiles were mostly exhibited in response to happy/smiling and spontaneously interacting partners. Overall, no effect of wearing a protective facemask emerged. The use of protective facemasks did not result in a lower display of social smiles. The findings suggest that FT and PT might be equally sensitive to their adult interactive partners in terms of social smiles displays at 2-3-month-age.

Developmental cascades of vocal turn-taking connect prelinguistic vocalizing with early language.

Conversational turn-taking is ubiquitously found in caregiver-infant interactions, and robustly predictive of infant communicative development. Over the first year, infants take quick adult-like vocal turns with caregivers. Many studies have documented the consistency of caregiver responsiveness and its influence on infant rapid language growth. However, few have examined how caregiver responsiveness facilitates extended vocal turn-taking in real-time with infants over the first year. The influence of prelinguistic vocal turn-taking on the emergence of language has also been under-investigated. We analyzed free-play sessions of 30 caregivers and their infants at both 5 and 10 months, and obtained infant language outcomes at 18 months. We examined the developmental consistency (group-level continuity and dyad-order stability) and change of infant volubility, caregiver responses to babbling in vocal, non-vocal and multimodal modalities, and the influence of modality on caregiver-infant vocal turn-taking. Caregiver contingent responsiveness to infant babbling at 5 months predicted vocal turn-taking at 10 months. Developmental increases in prelinguistic vocalizing and vocal turn-taking from 5 to 10 months predicted infant language outcomes at 18 months. At both 5 and 10 months, caregiver vocal responses were more effective in extending turn-taking than non-vocal or multimodal responses. In summary, prelinguistic vocal turn-taking, facilitated by caregiver vocal responsiveness, is positively related to the emergence of early language.

Variations in infants' physical and social environments shape spontaneous locomotion.

Independent locomotion is associated with a range of positive developmental outcomes, but unlike cognitive, linguistic, and social skills, acquiring motor skills requires infants to generate their own input for learning. We tested factors that shape infants' spontaneous locomotion by observing forty 12- to 22-month-olds (19 girls, 21 boys) during free play. Infants were recruited from the New York City area, and caregivers reported that 25 infants were White, six were Asian, four were Black, and five had multiple races; four were Hispanic or Latino. All infants played in four conditions: two environmental conditions (gross-motor toys, fine-motor toys) crossed with two social conditions (alone, together with a caregiver). Infants moved more in the gross-motor toy conditions than in the fine-motor toy conditions. However, the effect of playing with a caregiver differed by toy condition. In the gross-motor toy conditions, playing with a caregiver did not affect how much infants moved, but in the fine-motor toy conditions, playing with a caregiver further depressed infant locomotion. Infants with more walking experience moved more with gross-motor toys but not with fine-motor toys. Differences in the amount of locomotion between conditions were related to how infants used toys and the interactions between infants and caregivers. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The breadth and specificity of 18-month-old's infant-initiated interactions in naturalistic home settings.

Infants actively initiate social interactions aiming to elicit different types of responses from other people. This study aimed to document a variety of communicative interactions initiated by 18-month-old Turkish infants from diverse SES (N = 43) with their caregivers in their natural home settings. The infant-initiated interactions such as use of deictic gestures (e.g., pointing, holdouts), action demonstrations, vocalizations, and non-specific play actions were coded from video recordings and classified into two categories as need-based and non-need-based. Need-based interactions were further classified as a) biological (e.g., feeding); b) socio-emotional (e.g., cuddling), and non-need-based interactions (i.e., communicative intentions) were coded as a) expressive, b) requestive; c) information/help-seeking; d) information-giving. Infant-initiated non-need-based (88%) interactions were more prevalent compared to need-based interactions (12%). Among the non-need-based interactions, 50% aimed at expressing or sharing attention or emotion, 26% aimed at requesting an object or an action, and 12% aimed at seeking information or help. Infant-initiated information-giving events were rare. We further investigated the effects of familial SES and infant sex, finding no effect of either on the number of infant-initiated interactions. These findings suggest that at 18 months, infants actively communicate with their social partners to fulfil their need-based and non-need-based motivations using a wide range of verbal and nonverbal behaviors, regardless of their sex and socio-economic background. This study thoroughly characterizes a wide and detailed range of infant-initiated spontaneous communicative bids in hard-to-access contexts (infants' daily lives at home) and with a traditionally underrepresented non-WEIRD population.

Relationship between maternal anxiety and infants' temperament: The mediating role of mindful parenting.

Research has indicated that maternal anxiety does have an effect on infant temperament. Therefore, it is important to study the variables that could play a role in this relationship. In this study, we propose that mindful parenting could act as a mediator in this relationship. Thus, the main objective was to evaluate the relationship between maternal anxiety and child temperament (i.e., negative affectivity, surgency, and effortful control) through the mindful parenting of mothers. Mothers (N = 225) self-reported their anxiety, mindful parenting use, and the temperament of their old infants (aged 4-18 months). First, the reliability and validity results showed that the infant version of the Interpersonal Mindful Parenting questionnaire was a good tool for the assessment of mindful parenting among parents with infants. The five-factor structure of the questionnaire was confirmed; it involved self-regulation in the parenting relationship, listening with full attention, emotional awareness of the child, compassion for the child, and non-judgmental acceptance of parenting behavior. Correlational analyses showed that maternal anxiety was related to negative affectivity and effortful control in infants. Furthermore, mediational analyses indicated that the relation between maternal anxiety and infant negative affectivity was mediated by self-regulation in parenting and the emotional awareness of the child. In addition, the relation between maternal anxiety and infant effortful control was mediated by compassion for the child and listening with full attention. These results contribute to knowledge about the relation between maternal anxiety and child temperament, which may increase the risk of psychological symptoms. The results of this study suggest that promoting mindful parenting skills may be beneficial for affectivity and effortful control in infants.

It's You and Me: Infants' cross-modal communicative signals and mother-infant interactive behavior predict infant regulatory patterns in the still-face paradigm at 3 months.

Infant regulatory behavior develops since birth and impacts their early social interactions. Infants differ in the relative coherence and incoherence of their cross-modal communicative signals during en-face infant-caregiver interactions. We expand this research by evaluating whether different infant regulatory patterns observed during the Face-to-Face Still-Face (FFSF) at 3 months are associated with the coherence or incoherence of infants' cross-modal communicative behaviors during en-face interactions or with multiple dimensions of mother-infant interactive behavior during free-play. Analyses were based on data collected from 100 mother-infant dyads from urban, working- and middle-class backgrounds in Portugal who were videotaped during the FFSF and free play at 3 months. Results confirm that infants' different regulatory behavior patterns in the FFSF at 3 months are associated with the coherence and incoherence of their cross-modal interactive behaviors and specific aspects of mother-infant interaction. Infants with a Social-Positive oriented regulatory pattern during the FFSF displayed more coherent and less incoherent communicative behaviors with their mothers and were more cooperative during free play. In turn, their mothers were more sensitive. Our findings support the perspective that infants' regulatory behavior strategies in the context of caregiver regulatory support and sensitivity are likely to increase dyadic correspondence and infant ability to engage with the world.

Building language learning: Relations between infant attention and social contingency in the first year of life.

In Western societies, social contingency, or prompt and meaningful back-and-forth exchanges between infant and caregiver, is a powerful feature of the early language environment. Research suggests that infants with better attentional skills engage in more social contingency during interactions with adults and, in turn, social contingency supports infant attention. This reciprocity is theorized to build infant language skills as the adult capitalizes on and extends the infant's attention during socially contingent interactions. Using data from 104 infants and caregivers, this paper tests reciprocal relations between infant attention and social contingency at 6- and 12-months and the implications for infant vocabulary at 18-months. Infant attentional skills to social (women speaking) and nonsocial (objects dropping) events were assessed, and social contingency was examined during an 8-minute toy play interaction with a caregiver. Child receptive and expressive vocabulary was measured by caregiver-report. Both social and nonsocial attentional skills related to engagement in social contingency during caregiver-infant interaction, though only models that included social attention and social contingency predicted vocabulary. These findings provide empirical evidence for the proposed reciprocal relations between infant attention and social contingency as well as how they relate to later language.

Infant sustained attention differs by context and social content in the first 2 years of life.

Sustained attention (SA) is an endogenous form of attention that emerges in infancy and reflects cognitive engagement and processing. SA is critical for learning and has been measured using different methods during screen-based and interactive contexts involving social and nonsocial stimuli. How SA differs by measurement method, context, and stimuli across development in infancy is not fully understood. This 2-year longitudinal study examines attention using one measure of overall looking behavior and three measures of SA-mean look duration, percent time in heart rate-defined SA, and heart rate change during SA-in N = 53 infants from 1 to 24 months across four unique task conditions: social videos, nonsocial videos, social interactions (face-to-face play), and nonsocial interactions (toy engagement). Results suggest that developmental changes in attention differ by measurement method, task context (screen or interaction), and task stimulus (social or nonsocial). During social interactions, overall looking and look durations declined after age 3-4 months, whereas heart rate-defined attention measures remained stable. All SA measures were greater for videos than for live interaction conditions throughout the first 6 months, but SA to social and nonsocial stimuli within each task context were equivalent. In the second year of life, SA measured with look durations was greater for social videos compared to other conditions, heart rate-defined SA was greater for social videos compared to nonsocial interactions, and heart rate change during SA was similar across conditions. Together, these results suggest that different measures of attention to social and nonsocial stimuli may reflect unique developmental processes and are important to compare and consider together, particularly when using infant attention as a marker of typical or atypical development. RESEARCH HIGHLIGHTS: Attention measure, context, and social content uniquely differentiate developmental trajectories of attention in the first 2 years of life. Overall looking to caregivers during dyadic social interactions declines significantly from 4 to 6 months of age while sustained attention (SA) to caregivers remains stable. Heart rate-defined SA generally differentiates stimulus context where infants show greater SA while watching videos than while engaging with toys.

Parental sensitivity and intrusiveness with mothers and fathers: Associations between parental behavioral activation/inhibition and infant temperament.

Understanding the factors contributing to sensitive parenting is crucial to optimize infant social and emotional functioning. Research has supported the association between parents' personality and parenting quality, but findings are inconsistent when examining various global personality measures. Further, it is likely that the interaction between parent-level (e.g., personality) and infant-level characteristics (e.g., temperament) are more strongly associated with caregiving quality. Most studies examining predictors of parenting quality have only included mothers, compared to fathers. The current study examined the interaction between parental personality and infant temperament and associations with parental sensitivity and intrusiveness with mothers and fathers. The participants included families (n = 102) when the infants were 4, 6, and 8 months old. Using parent report measures and a face-to-face play task, significant main effects of maternal behavioral inhibition on parenting behaviors were observed for mothers. A Behavioral Activation X Infant Negative Reactivity interaction predicted both maternal sensitivity and intrusiveness, whereas a Behavioral Inhibition X Infant Surgency predicted paternal intrusiveness. In summary, the results revealed support for the goodness-of-fit perspective between parents' personality and infant temperament.

Caregiver encouragement to act on objects is related with crawling infants' receptive language.

The progression from crawling to walking in infancy is associated with changes in infant language development. One possible explanation for such change is the infant's language environment. Prior research indicates that caregivers use more action directives with walking infants compared to crawling infants, but the relations of such parental speech with infant vocabulary is unknown. Here, we present findings from day-long home audio recordings (Study 1) and laboratory observations (Study 2) of same-aged crawling and walking infants to explore how caregiver language, specifically action directives, were associated with parent reported infant vocabulary size. Findings in both studies indicated that caregiver action directives were associated with crawling, but not walking infants' receptive vocabulary sizes. Specifically, action directives about objects occurring when the infant and caregiver were not jointly engaged were associated with higher receptive vocabulary scores for crawling infants, but no such pattern was found for walking infants. The replication of results in distinct samples with different research methodologies strengthens the findings. Taken together, these studies demonstrate that caregiver social engagement specific to infant motoric development is related with infant language learning.