The haves and have-nots: Infants use wealth to guide social behavior and evaluation.

Biases favoring the wealthy are ubiquitous, and they support and bolster vast resource inequalities across individuals and groups; yet, when these biases are acquired remains unknown. In Experiments 1 through 5 (Total N = 232), using multiple methods, we found that 14- to 18-month-old infants track individuals' wealth (Experiments 1-5), prefer and selectively help rich (vs. poor) individuals (Experiments 2 and 3), and negatively evaluate poor individuals (Experiments 4 and 5). In two subsequent experiments with 11- to 13-month-old infants (Total N = 65), however, we find no evidence of preferences for rich (vs. poor) individuals (Experiment 6) or differential evaluations of rich and poor people (Experiment 7). Together, these results demonstrate that in the second year of life, wealth emerges as a central and robust dimension of evaluation that guides social decision making. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Associations of prenatal exposure to per- and polyfluoroalkyl substances (PFAS) with measures of cognition in 7.5-month-old infants: An exploratory study.

BACKGROUND: Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) has been linked to a wide array of adverse maternal and child health outcomes. However, studies examining PFAS in relation to offspring cognition have been inconclusive. OBJECTIVE: We examined whether prenatal exposure to a mixture of PFAS was related to cognition in 7.5-month-old infants. METHODS: Our analytic sample included participants enrolled in the Chemicals in Our Bodies (CIOB) and Illinois Kids Development Study (IKIDS) cohorts (N = 163). Seven PFAS were measured in 2nd trimester maternal serum samples and were detected in >65% of participants. Infant cognition was measured with a visual recognition memory task using an infrared eye tracker when infants were 7.5 months old. This task included familiarization trials where each infant was shown two identical faces and test trials where each infant was shown the familiar face paired with a novel face. In familiarization, we assessed average run duration (time looking at familiarization stimuli before looking away) as a measure of information processing speed, in addition to time to familiarization (time to reach 20 s of looking at stimuli) and shift rate (the number of times infants looked between stimuli), both as measures of attention. In test trials, we assessed novelty preference (proportion of time looking to the novel face) to measure recognition memory. Linear regression was used to estimate associations of individual PFAS with cognitive outcomes, while Bayesian kernel machine regression (BKMR) was used to estimate mixture effects. RESULTS: In adjusted single-PFAS linear regression models, an interquartile range increase in PFNA, PFOA, PFOS, PFHxS, PFDeA, and PFUdA was associated with an increase in shift rate, reflecting better visual attention. Using BKMR, increasing quartiles of the PFAS mixture was similarly associated with a modest increase in shift rate. There were no significant associations between PFAS exposure and time to reach familiarization (another measure of attention), average run duration (information processing speed), or novelty preference (visual recognition memory). CONCLUSION: In our study population, prenatal PFAS exposure was modestly associated with an increase in shift rate and was not strongly associated with any adverse cognitive outcomes in 7.5-month-old infants.

Cross-cultural applicability of eye-tracking in assessing attention to emotional faces in preschool-aged children.

Humans show an attention bias toward emotional versus neutral information, which is considered an adaptive pattern of information processing. Deviations from this pattern have been observed in children with socially withdrawn behaviors, with most research being conducted in controlled settings among children from urban areas. The goal of the current study was to examine the cross-cultural applicability of two eye-tracking-based measures in assessing attention biases and their relations to children's symptoms of socially withdrawn behaviors in two independent and diverse samples of preschool children. The cross-cultural comparison was conducted between the Navajo Birth Cohort study (NBCS), an indigenous cohort with relatively low socioeconomic status (SES), and the Illinois Kids Development study (IKIDS), a primarily Non-Hispanic White and high SES cohort. Children in both cohorts completed eye-tracking tasks with pictures of emotional faces, and mothers reported on children's symptoms of socially withdrawn behaviors. Results showed that general patterns of attention biases were mostly the same across samples, reflecting heightened attention toward emotional versus neutral faces. The differences across two samples mostly involved the magnitude of attention biases. NBCS children were slower to disengage from happy faces when these emotional faces were paired with neutral faces. Additionally, socially withdrawn children in the NBCS sample showed a pattern of attentional avoidance for emotional faces. The comparability of overall patterns of attention biases provides initial support for the cross-cultural applicability of the eye-tracking measures and demonstrates the robustness of these methods across clinical and community settings. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Prenatal PFAS and psychosocial stress exposures in relation to fetal growth in two pregnancy cohorts: Applying environmental mixture methods to chemical and non-chemical stressors.

BACKGROUND: Prenatal exposure to individual per­ and poly­fluoroalkyl substances (PFAS) and psychosocial stressors have been associated with reductions in fetal growth. Studies suggest cumulative or joint effects of chemical and non-chemical stressors on fetal growth. However, few studies have examined PFAS and non-chemical stressors together as a mixture, which better reflects real life exposure patterns. We examined joint associations between PFAS, perceived stress, and depression, and fetal growth using two approaches developed for exposure mixtures. METHODS: Pregnant participants were enrolled in the Chemicals in Our Bodies cohort and Illinois Kids Development Study, which together make up the ECHO.CA.IL cohort. Seven PFAS were previously measured in 2nd trimester maternal serum samples and were natural log transformed for analyses. Perceived stress and depression were assessed using self-reported validated questionnaires, which were converted to t-scores using validated methods. Quantile g-computation and Bayesian kernel machine regression (BKMR) were used to assess joint associations between PFAS, perceived stress and depression t-scores and birthweight z-scores (N = 876). RESULTS: Individual PFAS, depression and perceived stress t-scores were negatively correlated with birthweight z-scores. Using quantile g-computation, a simultaneous one quartile increase in all PFAS, perceived stress and depression t-scores was associated with a slight reduction in birthweight z-scores (mean change per quartile increase = -0.09, 95% confidence interval = -0.21,0.03). BKMR similarly indicated that cumulative PFAS and stress t-scores were modestly associated with lower birthweight z-scores. Across both methods, the joint association appeared to be distributed across multiple exposures rather than due to a single exposure. CONCLUSIONS: Our study is one of the first to examine the joint effects of chemical and non-chemical stressors on fetal growth using mixture methods. We found that PFAS, perceived stress, and depression in combination were modestly associated were lower birthweight z-scores, which supports prior studies indicating that chemical and non-chemical stressors are jointly associated with adverse health outcomes.

Associations of Maternal Stress, Prenatal Exposure to Per- and Polyfluoroalkyl Substances (PFAS), and Demographic Risk Factors with Birth Outcomes and Offspring Neurodevelopment: An Overview of the ECHO.CA.IL Prospective Birth Cohorts.

BACKGROUND: Infants whose mothers experience greater psychosocial stress and environmental chemical exposures during pregnancy may face greater rates of preterm birth, lower birth weight, and impaired neurodevelopment. METHODS: ECHO.CA.IL is composed of two cohorts, Chemicals in Our Bodies (CIOB; n = 822 pregnant women and n = 286 infants) and Illinois Kids Development Study (IKIDS; n = 565 mother-infant pairs), which recruit pregnant women from San Francisco, CA and Urbana-Champaign, IL, respectively. We examined associations between demographic characteristics and gestational age, birth weight z-scores, and cognition at 7.5 months across these two cohorts using linear models. We also examined differences in biomarkers of exposure to per- and polyfluoroalkyl substances (PFAS), measured in second-trimester serum, and psychosocial stressors by cohort and participant demographics. RESULTS: To date, these cohorts have recruited over 1300 pregnant women combined. IKIDS has mothers who are majority white (80%), whereas CIOB mothers are racially and ethnically diverse (38% white, 34% Hispanic, 17% Asian/Pacific Islander). Compared to CIOB, median levels of PFOS, a specific PFAS congener, are higher in IKIDS (2.45 ng/mL versus 1.94 ng/mL), while psychosocial stressors are higher among CIOB. Across both cohorts, women who were non-white and single had lower birth weight z-scores relative to white women and married women, respectively. Demographic characteristics are not associated with cognitive outcomes at 7.5 months. CONCLUSIONS: This profile of the ECHO.CA.IL cohort found that mothers and their infants who vary in terms of socioeconomic status, race/ethnicity, and geographic location are similar in many of our measures of exposures and cognitive outcomes. Similar to past work, we found that non-white and single women had lower birth weight infants than white and married women. We also found differences in levels of PFOS and psychosocial stressors based on geographic location.

Infants preferentially help individuals who label objects conventionally.

Recent evidence suggests that infants engage in selective prosocial behavior toward some individuals over others; the ways in which infants are selective can illuminate the origins of prosocial behaviors. Here, we explored selective helping behavior, investigating whether a target recipient's prior adherence to, or defiance of, social conventions affects infants' subsequent likelihood of helping the target individual. 19-month-old infants (N = 120) participated in an interaction with an experimenter who correctly labeled common objects, incorrectly labeled objects, or labeled objects with nonsense English-like labels. Infants' rates of helping were higher when the experimenter adhered to labeling conventions than when she defied labeling conventions by either labeling objects incorrectly or using unfamiliar nonsense labels. The current study provides evidence that infants use information about adhering to conventions to guide their helping behavior. These findings help to document the ways in which infants are selective in their helping behavior as well as possible origins of prosocial obligations toward ingroup members.

Similarity in transgender and cisgender children's gender development.

Gender is one of the central categories organizing children's social world. Clear patterns of gender development have been well-documented among cisgender children (i.e., children who identify as a gender that is typically associated with their sex assigned at birth). We present a comprehensive study of gender development (e.g., gender identity and gender expression) in a cohort of 3- to 12-y-old transgender children (n = 317) who, in early childhood, are identifying and living as a gender different from their assigned sex. Four primary findings emerged. First, transgender children strongly identify as members of their current gender group and show gender-typed preferences and behaviors that are strongly associated with their current gender, not the gender typically associated with their sex assigned at birth. Second, transgender children's gender identity (i.e., the gender they feel they are) and gender-typed preferences generally did not differ from 2 comparison groups: cisgender siblings (n = 189) and cisgender controls (n = 316). Third, transgender and cisgender children's patterns of gender development showed coherence across measures. Finally, we observed minimal or no differences in gender identity or preferences as a function of how long transgender children had lived as their current gender. Our findings suggest that early sex assignment and parental rearing based on that sex assignment do not always define how a child identifies or expresses gender later.

Infants' prosocial behavior is governed by cost-benefit analyses.

Cost-benefit analyses are central to mature decision-making and behavior across a range of contexts. Given debates regarding the nature of infants' prosociality, we investigated whether 18-month-old infants' (N = 160) prosocial behavior is impacted by anticipated costs and benefits. Infants participated in a helping task in which they could carry either a heavy or light block across a room to help an experimenter. Infants' helping behavior was attenuated when the anticipated physical costs were high versus low (Experiment 1), and high-cost helping was enhanced under conditions of increased intrinsic motivational benefits (Experiments 2 and 3). High-cost helping was further predicted by infants' months of walking experience, presumably because carrying a heavy block across a room is more effortful for less experienced walkers than for more experienced walkers demonstrating that infants subjectively calibrate costs. Thus, infants' prosocial responding may be guided by a rational decision-making process that weighs and integrates costs and benefits.

The origins of infants' fairness concerns and links to prosocial behavior.

Concerns about fairness are central to mature moral judgments. We review research regarding the origins of a sensitivity to distributive fairness, and how it relates to early sharing. Infants' sensitivity to fairness appears to be commensurate with that of school-age children: infants notice violations to fairness norms and evaluate individuals based on their fair or unfair behavior. However, it may differ in other ways: there is no evidence that infants punish unfair individuals. Sharing behavior plays a role in both the developmental emergence of, and subsequent individual differences in, infants' fairness concerns. These results motivate novel questions, such whether infants can entertain other models of fairness, whether infants' socio-moral concerns hang together, and the relationship early fairness sensitivities and later fair behavior.

Do transgender children (gender) stereotype less than their peers and siblings?

In the present work, we ask whether socially transitioned, transgender children differ from other children in their endorsement of gender stereotypes and response to others' gender nonconformity. We compare transgender children (N = 56) to a group of siblings of transgender children (N = 37), and a group of unrelated control participants (N = 56) during middle childhood (ages 6-8 years old). Our results indicate that transgender children and the siblings of transgender children endorse gender stereotypes less than the control group. Further, transgender children see violations of gender stereotypes as more acceptable, and they are more willing to indicate a desire to befriend and attend school with someone who violates gender stereotypes than the control participants. These results held after statistically controlling for demographic differences between families with and without transgender children. We discuss several possible reasons that can explain these differences.

'To the victor go the spoils': Infants expect resources to align with dominance structures.

Previous research has found that within the first year of life infants possess rich knowledge about social structures (i.e., that some individuals are dominant over other individuals) as well as expectations about resource distributions (i.e., that resources are typically distributed equally to recipients). We investigated whether infants' expectations about resource distribution can be modulated by information about the dominance structure between the recipients. We first replicated the finding that infants attribute a stable dominance hierarchy to a pair of individuals when their goals conflicted and one individual yielded to the other (Expt. 1), and that this sensitivity is not driven by lower-level perceptual factors (Expt. 2). In Experiments 3-5, we tested our main hypothesis that infants' attention to equal and unequal distributions varies as a function of prior social dominance information. We first replicated and extended prior work by establishing that infants looked significantly longer to unequal than equal resource distributions when no prior information about dominance was provided about recipients (Expt. 3). Critically, following social dominance information, infants looked significantly longer to an equal distribution of resources than a distribution that favored the dominant individual (Expt. 4), and looked significantly longer when the submissive individual received more resources compared to when the dominant individual received more resources (Expts. 4 and 5). Together, these findings suggest that infants expect resources to align with social dominance structures.