Attachment security, environmental adversity, and fast life history behavioral profiles in human adolescents.

One species-general life history (LH) principle posits that challenging childhood environments are coupled with a fast or faster LH strategy and associated behaviors, while secure and stable childhood environments foster behaviors conducive to a slow or slower LH strategy. This coupling between environments and LH strategies is based on the assumption that individuals' internal traits and states are independent of their external surroundings. In reality, individuals respond to external environmental conditions in alignment with their intrinsic vitality, encompassing both physical and mental states. The present study investigated attachment as an internal mental state, examining its role in mediating and moderating the association between external environmental adversity and fast LH strategies. A sample of 1169 adolescents (51% girls) from 9 countries was tracked over 10 years, starting from age 8. The results confirm both mediation and moderation and, for moderation, secure attachment nullified and insecure attachment maintained the environment-LH coupling. These findings suggest that attachment could act as an internal regulator, disrupting the contingent coupling between environmental adversity and a faster pace of life, consequently decelerating human LH.

Examining How National Levels of Life Expectancy, Education, and Income Influence Early Childhood Development: The Mediating Role of the Child's Nurturing Context.

OBJECTIVE: Forty-three percent of children younger than 5 years in low- and middle-income countries (LMICs) are at risk of not meeting their developmental potential. This study investigated how 3 aspects of national development (national life expectancy, education, and income levels) are associated with early childhood development by influencing 5 domains of nurturing care (caregiving, the learning environment, safety and security, nutrition, and the health of the home environment). METHODS: In total, 159,959 families with children aged 36 to 59 months living in 51 LMICs provided data. National development was measured using 3 indicators (national life expectancy, education, and income levels), and nurturing care was measured using 10 indicators that collectively captured the 5 nurturing care domains. Path analyses examined how nurturing care indicators mediated the effects of national development on early childhood development. RESULTS: Higher national life expectancy was directly associated with more advanced childhood development. Higher national levels of education and income were indirectly associated with more advanced childhood development through aspects of nurturing care, such as reduced caregiver psychological aggression or physical violence, increased learning materials and wired appliances in the home environment, and greater caregiver education and child height-for-age. Greater caregiver cognitive caregiving practices promoted childhood development, regardless of levels of national development. CONCLUSION: Intervening to promote caregiver education, appropriate discipline strategies, cognitive caregiving practices, and family access to wired appliances, learning materials, and adequate nutrition is key to promoting childhood development in nations with lower levels of national development.

Cultural values, parenting, and child adjustment in the United States.

We examined whether cultural values, conformity and parenting behaviours were related to child adjustment in middle childhood in the United States. White, Black and Latino mothers (n = 273), fathers (n = 182) and their children (n = 272) reported on parental individualism and collectivism, conformity values, parental warmth, monitoring, family obligation expectations, and child internalising and externalising behaviours. Mean differences, bivariate correlations and multiple regression analyses were performed on variables of interest. Collectivism in mothers and fathers was associated with family obligation expectations and parental warmth. Fathers with higher conformity values had higher expectations of children's family obligations. Child internalising and externalising behaviours were greater when Latino families subscribed to individualistic values. These results are discussed in the context of cultural values, protective and promotive factors of behaviour, and race/ethnicity in the United States.

Human cardiac metabolism.

The heart is the most metabolically active organ in the human body, and cardiac metabolism has been studied for decades. However, the bulk of studies have focused on animal models. The objective of this review is to summarize specifically what is known about cardiac metabolism in humans. Techniques available to study human cardiac metabolism are first discussed, followed by a review of human cardiac metabolism in health and in heart failure. Mechanistic insights, where available, are reviewed, and the evidence for the contribution of metabolic insufficiency to heart failure, as well as past and current attempts at metabolism-based therapies, is also discussed.

Visual stimulus structure, visual system neural activity, and visual behavior in young human infants.

In visual perception and information processing, a cascade of associations is hypothesized to flow from the structure of the visual stimulus to neural activity along the retinogeniculostriate visual system to behavior and action. Do visual perception and information processing adhere to this cascade near the beginning of life? To date, this three-stage hypothetical cascade has not been comprehensively tested in infants. In two related experiments, we attempted to expose this cascade in 6-month-old infants. Specifically, we presented infants with two levels of visual stimulus intensity, we measured electrical activity at the infant cortex, and we assessed infants' preferential looking behavior. Chromatic saturation provided a convenient stimulus dimension to test the cascade because greater saturation is known to excite increased activity in the primate visual system and is generally hypothesized to stimulate visual preference. Experiment 1 revealed that infants prefer (look longer) at the more saturated of two colors otherwise matched in hue and brightness. Experiment 2 showed increased aggregate neural cortical excitation in infants (and adults) to the more saturated of the same pair of colors. Thus, experiments 1 and 2 taken together confirm a cascade: Visual stimulation of relatively greater intensity evokes relatively greater levels of bioelectrical cortical activity which in turn is associated with relatively greater visual attention. As this cascade obtains near the beginning of life, it helps to account for early visual preferences and visual information processing.

Individualism, collectivism and conformity in nine countries: Relations with parenting and child adjustment.

This study investigated how individualism, collectivism and conformity are associated with parenting and child adjustment in 1297 families with 10-year-old children from 13 cultural groups in nine countries. With multilevel models disaggregating between- and within-culture effects, we examined between- and within-culture associations between maternal and paternal cultural values, parenting dimensions and children's adjustment. Mothers from cultures endorsing higher collectivism and fathers from cultures endorsing lower individualism engage more frequently in warm parenting behaviours. Mothers and fathers with higher-than-average collectivism in their culture reported higher parent warmth and expectations for children's family obligations. Mothers with higher-than-average collectivism in their cultures more frequently reported warm parenting and fewer externalising problems in children, whereas mothers with higher-than-average individualism in their culture reported more child adjustment problems. Mothers with higher-than-average conformity values in their culture reported more father-displays of warmth and greater mother-reported expectations for children's family obligations. Fathers with higher-than-average individualism in their culture reported setting more rules and soliciting more knowledge about their children's whereabouts. Fathers who endorsed higher-than-average conformity in their culture displayed more warmth and expectations for children's family obligations and granted them more autonomy. Being connected to an interdependent, cohesive group appears to relate to parenting and children's adjustment.

Infants of mothers with early remitted clinical depression and mothers with no postpartum depression: Adaptive functioning in the second year of life.

Whether and how remitted clinical depression in postpartum motherhood contributes to poor infant adaptive functioning is inconclusive. The present longitudinal study examines adaptive functioning in infants of mothers diagnosed as clinically depressed at 5 months but remitted at 15 and 24 months. Fifty-five U. S. mothers with early, remitted clinical depression and 132 mothers without postpartum depression completed the Vineland Adaptive Behavior Scales about their infants at 15 and 24 months. Between groups, mothers were equivalent in age, ethnicity, marital status, and receptive vocabulary (a proxy for verbal intelligence), and infants were equivalent in age and distribution of gender. Controlling for maternal education and parity, mothers with early, remitted clinical depression and mothers with no postpartum depression rated their infants similarly on communication, daily living skills, and socialization. Mothers with early, remitted clinical depression rated their infants poorer in motor skills. Girls were rated more advanced than boys in communication at 24 months and daily living skills at 15 and 24 months. Rated infant adaptive behavior skills increased from 15 to 24 months. With exceptions, adaptive functioning in infants may be robust to early, remitted maternal depression, and adaptive functioning presents a domain to promote positive development in this otherwise vulnerable population.

Si la depresión clínica remitida en la maternidad del período de postparto contribuye y cómo contribuye al débil funcionamiento de adaptación del infante es algo inconcluso. El presente estudio longitudinal examina el funcionamiento de adaptación en infantes de madres clínicamente deprimidas a los 5 meses, pero remitidas a los 15 y 24 meses. Cincuenta y cinco madres con una temprana depresión clínica remitida y 132 madres sin depresión en el período de postparto en los Estados Unidos completaron las Escalas Vineland del Comportamiento de Adaptación acerca de sus infantes de 15 y 24 meses de edad. Entre los grupos, las madres presentaban equivalencia en cuanto a la edad, la etnicidad, el estado marital, así como el vocabulario receptivo (un reemplazo para la inteligencia verbal), y los infantes presentaban equivalencia en edad y género. Con los factores de educación y paridad controlados, las madres con temprana depresión clínica remitida y las madres sin depresión en el período de postparto evaluaron a sus infantes similarmente en cuanto a la comunicación, las habilidades del diario vivir y la socialización. Las madres con temprana depresión clínica remitida evaluaron a sus infantes más pobremente en cuanto a habilidades motoras. A las niñas se les evaluó como más avanzadas que los varones en la comunicación a los 24 meses y en las habilidades del diario vivir a los 15 y 24 meses. Las evaluadas habilidades del comportamiento de adaptación de los infantes aumentaron de los 15 a los 24 meses. Con excepciones, el funcionamiento de adaptación en los infantes pudiera ser robusto en relación con la temprana depresión materna remitida, y el funcionamiento de adaptación presenta un dominio para promover el positivo desarrollo en este grupo de población que, de lo contrario, es vulnerable.

Adolescents' relationships with parents and romantic partners in eight countries.

INTRODUCTION: Creating romantic relationships characterized by high-quality, satisfaction, few conflicts, and reasoning strategies to handle conflicts is an important developmental task for adolescents connected to the relational models they receive from their parents. This study examines how parent-adolescent conflicts, attachment, positive parenting, and communication are related to adolescents' romantic relationship quality, satisfaction, conflicts, and management. METHOD: We interviewed 311 adolescents at two time points (females = 52%, ages 15 and 17) in eight countries (China, Colombia, Italy, Kenya, the Philippines, Sweden, Thailand, and the United States). Generalized and linear mixed models were run considering the participants' nesting within countries. RESULTS: Adolescents with negative conflicts with their parents reported low romantic relationship quality and satisfaction and high conflicts with their romantic partners. Adolescents experiencing an anxious attachment to their parents reported low romantic relationship quality, while adolescents with positive parenting showed high romantic relationship satisfaction. However, no association between parent-adolescent relationships and conflict management skills involving reasoning with the partner was found. No associations of parent-adolescent communication with romantic relationship dimensions emerged, nor was there any effect of the country on romantic relationship quality or satisfaction. CONCLUSION: These results stress the relevance of parent-adolescent conflicts and attachment as factors connected to how adolescents experience romantic relationships.

Comparing apples to manzanas and oranges to naranjas: A new measure of English-Spanish vocabulary for dual language learners.

The valid assessment of vocabulary development in dual-language-learning infants is critical to developmental science. We developed the Dual Language Learners English-Spanish (DLL-ES) Inventories to measure vocabularies of U.S. English-Spanish DLLs. The inventories provide translation equivalents for all Spanish and English items on Communicative Development Inventory (CDI) short forms; extended inventories based on CDI long forms; and Spanish language-variety options. Item-Response Theory analyses applied to Wordbank and Web-CDI data (n = 2603, 12-18 months; n = 6722, 16-36 months; half female; 1% Asian, 3% Black, 2% Hispanic, 30% White, 64% unknown) showed near-perfect associations between DLL-ES and CDI long-form scores. Interviews with 10 Hispanic mothers of 18- to 24-month-olds (2 White, 1 Black, 7 multi-racial; 6 female) provide a proof of concept for the value of the DLL-ES for assessing the vocabularies of DLLs.

How adolescents' lives were disrupted over the course of the COVID-19 pandemic: A longitudinal investigation in 12 cultural groups in 9 nations from March 2020 to July 2022.

It is unclear how much adolescents' lives were disrupted throughout the COVID-19 pandemic or what risk factors predicted such disruption. To answer these questions, 1,080 adolescents in 9 nations were surveyed 5 times from March 2020 to July 2022. Rates of adolescent COVID-19 life disruption were stable and high. Adolescents who, compared to their peers, lived in nations with higher national COVID-19 death rates, lived in nations with less stringent COVID-19 mitigation strategies, had less confidence in their government's response to COVID-19, complied at higher rates with COVID-19 control measures, experienced the death of someone they knew due to COVID-19, or experienced more internalizing, externalizing, and smoking problems reported more life disruption due to COVID-19 during part or all of the pandemic. Additionally, when, compared to their typical levels of functioning, adolescents experienced spikes in national death rates, experienced less stringent COVID-19 mitigation measures, experienced less confidence in government response to the COVID-19 pandemic, complied at higher rates with COVID-19 control measures, experienced more internalizing problems, or smoked more at various periods during the pandemic, they also experienced more COVID-19 life disruption. Collectively, these findings provide new insights that policymakers can use to prevent the disruption of adolescents' lives in future pandemics.

Titin-Truncating variants Predispose to Dilated Cardiomyopathy in Diverse Populations.

Importance: The effect of high percentage spliced in (hiPSI) TTN truncating variants (TTNtvs) on risk of dilated cardiomyopathy (DCM) has historically been studied among population subgroups defined by genetic similarity to European reference populations. This has raised questions about the effect of TTNtvs in diverse populations, especially among individuals genetically similar to African reference populations. Objective: To determine the effect of TTNtvs on risk of DCM in diverse population as measured by genetic distance (GD) in principal component (PC) space. Design: Cohort study. Setting: Penn Medicine Biobank (PMBB) is a large, diverse biobank. Participants: Participants were recruited from across the Penn Medicine healthcare system and volunteered to have their electronic health records linked to biospecimen data including DNA which has undergone whole exome sequencing. Main Outcomes and Measures: Risk of DCM among individuals carrying a hiPSI TTNtv. Results: Carrying a hiPSI TTNtv was associated with DCM among PMBB participants across a range of GD deciles from the 1000G European centroid; the effect estimates ranged from odds ratio (OR) = 3.29 (95% confidence interval [CI] 1.26 to 8.56) to OR = 9.39 (95% CI 3.82 to 23.13). When individuals were assigned to population subgroups based on genetic similarity to the 1000G reference populations, hiPSI TTNtvs conferred significant risk of DCM among those genetically similar to the 1000G European reference population (OR = 7.55, 95% CI 4.99 to 11.42, P<0.001) and individuals genetically similar to the 1000G African reference population (OR 3.50, 95% CI 1.48 to 8.24, P=0.004). Conclusions and Relevance: TTNtvs are associated with increased risk of DCM among a diverse cohort. There is no significant difference in effect of TTNtvs on DCM risk across deciles of GD from the 1000G European centroid, suggesting genetic background should not be considered when screening individuals for titin-related DCM.

Intraindividual variability in parental acceptance-rejection predicts externalizing and internalizing symptoms across childhood/adolescence in nine countries.

Parenting that is high in rejection and low in acceptance is associated with higher levels of internalizing (INT) and externalizing (EXT) problems in children and adolescents. These symptoms develop and can increase in severity to negatively impact adolescents' social, academic, and emotional functioning. However, there are two major gaps in the extant literature: (a) nearly all prior research has focused on between-person differences in acceptance/rejection at the expense of examining intraindividual variability (IIV) across time in acceptance/rejection; and (b) no prior studies examine IIV in acceptance/rejection in diverse international samples. The present study utilized six waves of data with 1,199 adolescents' families living in nine countries from the Parenting Across Cultures study to test the hypotheses that (1) higher amounts of youth IIV in mother acceptance/rejection predict higher internalizing and (2) externalizing symptoms, and (3) that higher youth IIV in father acceptance/rejection predict higher internalizing, and (4) externalizing symptoms. Meta-analytic techniques indicated a significant, positive effect of IIV in child-reported mother and father acceptance/rejection on adolescent externalizing symptoms, and a significant positive effect of IIV in father acceptance/rejection on internalizing symptoms. The weighted effect for mother acceptance/rejection on internalizing symptoms was not statistically significant. Additionally, there was significant heterogeneity in all meta-analytic estimates. More variability over time in experiences of parental acceptance/rejection predicts internalizing and externalizing symptoms as children transition into adolescence, and this effect is present across multiple diverse samples. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Developmental Trajectories of Parental Self-Efficacy as Children Transition to Adolescence in Nine Countries: Latent Growth Curve Analyses.

Little is known about the developmental trajectories of parental self-efficacy as children transition into adolescence. This study examined parental self-efficacy among mothers and fathers over 3 1/2 years representing this transition, and whether the level and developmental trajectory of parental self-efficacy varied by cultural group. Data were drawn from three waves of the Parenting Across Cultures (PAC) project, a large-scale longitudinal, cross-cultural study, and included 1178 mothers and 1041 fathers of children who averaged 9.72 years of age at T1 (51.2% girls). Parents were from nine countries (12 ethnic/cultural groups), which were categorized into those with a predominant collectivistic (i.e., China, Kenya, Philippines, Thailand, Colombia, and Jordan) or individualistic (i.e., Italy, Sweden, and USA) cultural orientation based on Hofstede's Individualism Index (Hofstede Insights, 2021). Latent growth curve analyses supported the hypothesis that parental self-efficacy would decline as children transition into adolescence only for parents from more individualistic countries; parental self-efficacy increased over the same years among parents from more collectivistic countries. Secondary exploratory analyses showed that some demographic characteristics predicted the level and trajectory of parental self-efficacy differently for parents in more individualistic and more collectivistic countries. Results suggest that declines in parental self-efficacy documented in previous research are culturally influenced.

Comprehensive quantification of metabolic flux during acute cold stress in mice.

Cold-induced thermogenesis (CIT) is widely studied as a potential avenue to treat obesity, but a thorough understanding of the metabolic changes driving CIT is lacking. Here, we present a comprehensive and quantitative analysis of the metabolic response to acute cold exposure, leveraging metabolomic profiling and minimally perturbative isotope tracing studies in unanesthetized mice. During cold exposure, brown adipose tissue (BAT) primarily fueled the tricarboxylic acid (TCA) cycle with fat in fasted mice and glucose in fed mice, underscoring BAT's metabolic flexibility. BAT minimally used branched-chain amino acids or ketones, which were instead avidly consumed by muscle during cold exposure. Surprisingly, isotopic labeling analyses revealed that BAT uses glucose largely for TCA anaplerosis via pyruvate carboxylation. Finally, we find that cold-induced hepatic gluconeogenesis is critical for CIT during fasting, demonstrating a key functional role for glucose metabolism. Together, these findings provide a detailed map of the metabolic rewiring driving acute CIT.

The Home Environments of Infants of Mothers with Early, Remitted Clinical Depression and No Depression during the First Two Years Postpartum.

The current study examines stability, continuity, and group and gender differences in the home environments of infants of mothers with early, remitted clinical depression and no postpartum depression, overcoming methodological variations in the extant literature. Fifty-five mothers diagnosed with clinical depression (major or minor depression, dysthymia, or depressive disorder not otherwise specified) at 5 months and fully remitted by 15 and 24 months, and 132 mothers with no postpartum depression (Mage = 32.47; 69.7% European American) completed the Home Observation for Measurement of the Environment (HOME) Inventory Infant/Toddler version when their infants were 15 and 24 months old. No differences in stability estimates of the HOME scales were found between the groups. In terms of continuity, controlling for maternal education and infant birth order, HOME responsivity, involvement, and total score decreased, while HOME acceptance increased between 15 and 24 months in the full sample. There were no effects of group or gender. Results may point to the home environment as a key protective factor for infants of mothers with early, remitted clinical depression, or findings may suggest improved maternal parenting cognitions and practices following remission.

Coregulation: A Multilevel Approach via Biology and Behavior.

In this article, we explore the concept of coregulation, which encompasses the mutual adaptation between partners in response to one another's biology and behavior. Coregulation operates at both biological (hormonal and nervous system) and behavioral (affective and cognitive) levels and plays a crucial role in the development of self-regulation. Coregulation extends beyond the actions of individuals in a dyad and involves interactive contributions of both partners. We use as an example parent-child coregulation, which is pervasive and expected, as it emerges from shared genetic relatedness, cohabitation, continuous interaction, and the influence of common factors like culture, which facilitate interpersonal coregulation. We also highlight the emerging field of neural attunement, which investigates the coordination of brain-based neural activities between individuals, particularly in social interactions. Understanding the mechanisms and significance of neural attunement adds a new dimension to our understanding of coregulation and its implications for parent-child relationships and child development.

The nature and structure of maternal parenting practices and infant behaviors in U.S. national and international samples.

Methods: Twenty maternal parenting practices and 15 behaviors of their 5½- month-old infants in a U.S. national sample (N = 360) and 9 international samples (N = 653) were microcoded from videorecords of naturalistic interactions at home and aggregated into domains. Altogether, the samples were recruited from Argentina, Belgium, Brazil, France, Israel, Italy, Japan, Kenya, as well as the United States. Background and Rationale: A previous test of three competing models of the nature and structure of the maternal parenting practices supported a hybrid 2 factor/6 domain model as superior to a 1-factor dimensional model and a multi-factor style model: Maternal parenting practices are structured into nurture, physical, social, didactic, material, and language domains undergirded by dyadic and extradyadic factors. Infant behaviors were organized into physical, social, exploration, nondistress vocalization, and distress communication domains. The current study sought to examine links connecting these previously identified maternal domains and factors with infant behavior domains using structural equation models. Results: Mothers' dyadic factor is associated with infant social behaviors with mother; and mothers' extradyadic factor and encouragement of infant physical development are associated with infant exploration of their immediate physical environment and physical development. Infant distress communication (and less nondistress vocalization) is associated with more maternal nurturing. Discussion: Mothers' parenting practices in the middle of the first year of infant life are commonly structured and adapted to specific needs and developmental tasks of infants. Evaluations of mother-infant interactions with national and international samples permit a wide yet judicious analysis of common vs. specific models of mother-infant relationships.

A Scientometric Review of Infant Cry and Caregiver Responsiveness: Literature Trends and Research Gaps over 60 Years of Developmental Study.

Infant cry is an adaptive signal of distress that elicits timely and mostly appropriate caring behaviors. Caregivers are typically able to decode the meaning of the cry and respond appropriately, but maladaptive caregiver responses are common and, in the worst cases, can lead to harmful events. To tackle the importance of studying cry patterns and caregivers' responses, this review aims to identify key documents and thematic trends in the literature as well as existing research gaps. To do so, we conducted a scientometric review of 723 documents downloaded from Scopus and performed a document co-citation analysis. The most impactful publication was authored by Barr in 1990, which describes typical developmental patterns of infant cry. Six major research thematic clusters emerged from the analysis of the literature. Clusters were renamed "Neonatal Pain Analyzer" (average year of publication = 2002), "Abusive Head Trauma" (average year of publication = 2007), "Oxytocin" (average year of publication = 2009), "Antecedents of Maternal Sensitivity" (average year of publication = 2010), "Neurobiology of Parental Responses" (average year of publication = 2011), and "Hormonal Changes & Cry Responsiveness" (average year of publication = 2016). Research clusters are discussed on the basis of a qualitative inspection of the manuscripts. Current trends in research focus on the neurobiology of caregiver responses and the identification of factors promoting maternal sensitivity. Recent studies have also developed evidence-based strategies for calming crying babies and preventing caregivers' maladaptive responses. From the clusters, two topics conspicuously call for future research: fathers' responsiveness to infant cry and the impact of caregiver relationship quality on cry responsiveness.

Electrophysiological Evidence for Interhemispheric Connectivity and Communication in Young Human Infants.

Little is known empirically about connectivity and communication between the two hemispheres of the brain in the first year of life, and what theoretical opinion exists appears to be at variance with the meager extant anatomical evidence. To shed initial light on the question of interhemispheric connectivity and communication, this study investigated brain correlates of interhemispheric transmission of information in young human infants. We analyzed EEG data from 12 4-month-olds undergoing a face-related oddball ERP protocol. The activity in the contralateral hemisphere differed between odd-same and odd-difference trials, with the odd-different response being weaker than the response during odd-same trials. The infants' contralateral hemisphere "recognized" the odd familiar stimulus and "discriminated" the odd-different one. These findings demonstrate connectivity and communication between the two hemispheres of the brain in the first year of life and lead to a better understanding of the functional integrity of the developing human infant brain.

A Quantitative Evaluation of Thin Slice Sampling for Parent-Infant Interactions.

Behavioural coding is time-intensive and laborious. Thin slice sampling provides an alternative approach, aiming to alleviate the coding burden. However, little is understood about whether different behaviours coded over thin slices are comparable to those same behaviours over entire interactions. To provide quantitative evidence for the value of thin slice sampling for a variety of behaviours. We used data from three populations of parent-infant interactions: mother-infant dyads from the Grown in Wales (GiW) cohort (n = 31), mother-infant dyads from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort (n = 14), and father-infant dyads from the ALSPAC cohort (n = 11). Mean infant ages were 13.8, 6.8, and 7.1 months, respectively. Interactions were coded using a comprehensive coding scheme comprised of 11-14 behavioural groups, with each group comprised of 3-13 mutually exclusive behaviours. We calculated frequencies of verbal and non-verbal behaviours, transition matrices (probability of transitioning between behaviours, e.g., from looking at the infant to looking at a distraction) and stationary distributions (long-term proportion of time spent within behavioural states) for 15 thin slices of full, 5-min interactions. Measures drawn from the full sessions were compared to those from 1-, 2-, 3- and 4-min slices. We identified many instances where thin slice sampling (i.e., < 5 min) was an appropriate coding method, although we observed significant variation across different behaviours. We thereby used this information to provide detailed guidance to researchers regarding how long to code for each behaviour depending on their objectives.