Large scale studies have documented socioeconomic (SES) and racial/ethnic disparities in children's standardized math achievement at kindergarten entry. These early math skills predict future mathematics achievement and career success. However, limited research has been conducted using large sample sizes to understand how SES and race/ethnicity are related to children's numerical skills at even younger ages. The current study aims to investigate sociodemographic variability in three fundamental areas of early numeracy: nonverbal numerosity discrimination, rote counting, and cardinal number word knowledge. In addition, we will examine if the relations between numerical skills might be explained by their shared correlations to sociodemographic factors and if differences in numerical skills between sociodemographic groups can be explained by variability in working memory. Finally, we also investigate whether childcare attendance moderates early sociodemographic differences in numerical abilities. To achieve these goals, data from children aged 2; 6-6; 0 will be gathered from ∼ 45 US sites, drawn from a larger multi-lab international project (ManyNumbers project). The findings of this research will enhance our understanding of early emerging variability in numerical skills and provide insights into developing responsive and inclusive educational practices that support diverse learning needs in the early years. SUMMARY: Early mathematical skills are crucial for long-term academic and career achievement. SES and race/ethnicity-related disparities in math achievement emerge as early as preschool. Most studies use standardized math assessments that combine different numerical skills to assess achievement gaps, leaving uncertain which specific skills vary with demographic variables. We explore disparities in developmentally significant numerical skills and their relation to demographic variables. We also report relations between WM, childcare attendance and numerical skills. Data from approximately N = 1080 children aged 2;6-6;0 will be collected from ∼ 45 US labs, including demographic information and numeracy measures.

Recent studies (Cheung et al., 2017; Chu et al., 2020; Sullivan et al., 2023) argue that children may infer the existence of infinite magnitudes through experience with number words, which provide a system of rules for generating ever-larger numbers. We tested this hypothesis by investigating the development of children's infinity beliefs in two languages - English and Hindi - whose counting systems differ with respect to the transparency of their rules. In a study with 240 four- to eight-year-old children, we found that children who learn to count in English (n = 120) demonstrated both greater counting proficiency and better understanding of the successor relations between numbers relative to children who learn to count in Hindi (n = 120). We also found that children's infinity beliefs were associated with their mastery of the verbal count list, but the proportion of children who endorsed the belief that numbers are infinite did not differ across languages. We conclude that transparency of the linguistic structure of a counting system may be important for understanding the rules governing counting, but in contrast to previous studies, suggest that the direct relationship between these rules and beliefs about the boundless nature of number words may be weak. The implications of these findings and avenues for future research are discussed.

In the years following the acute COVID-19 crisis, facemask mandates became increasingly rare, rendering masking a highly visible personal choice. Across three studies conducted in the U.S. in 2022 and 2023 (N = 2,973), the current work provided a novel exploration of the potential impacts of adhering to vs. deviating from group masking norms within college classrooms. Experiments 1 and 2 used causal methods to assess the impact of hypothetical target students' masking behavior on participants' beliefs about that student's classroom fit (e.g., how well they fit in, how much their professor likes them, whether they are invited to study group). Maskers were expected to experience more classroom inclusion relative to non-maskers, but the largest effects were conformity effects: participants expected that students who deviated from a class's dominant mask-wearing behavior would experience massively lower classroom fit. Study 3 used correlational and qualitative methods to establish the real-world impact of mask conformity in a diverse sample of college students. Students reported believing that masking-and mask conformity-impacted others' perceptions of them, and reported avoiding deviating from masking norms. Students reported that their desire for mask-conformity impacted both their willingness to enroll in courses and their actual masking behavior, suggesting both academic and public health impacts. Across all three studies, we asked whether pressures to conform have disproportionate effects on particular groups, by exploring the effects of gender (Studies 1 and 3), immune-status (Studies 2 and 3) and race (Study 3). Our data raise important issues that should be considered when determining whether to e.g., enact mask mandates within college classrooms and beyond, and for understanding the cognitive and social consequences of mask wearing.

What drives children's early beliefs about disease transmission and prevention? We taught children (N = 152; 3;0-7;11) about three ailments (COVID-19, a novel disease Zerpox, bike-related injury) and the Personal Protective Equipment (PPE) used to prevent them (facemasks, earmuffs, helmets). Children then saw pairs of characters and decided who was safer from [getting sick/hurt]. In a preregistered 2x3x2 within-subjects design, we manipulated whether each character wore PPE or not, whether they wore the correct PPE for the ailment, and whether they wore the PPE properly. Children displayed stronger knowledge of PPE for preventing injury than illness, although there were large age effects. Performance on COVID-19 trials was generally similar to Zerpox trials, suggesting similar reasoning about novel and more familiar diseases. We classified children's performance based on the folk theories that might underlay their behavior, showing a strong reliance on theories other than germ theory in shaping performance.

When children first learn to count, what do they understand about the structure of the count system? The present study investigated English-speaking children’s ability to generalize the rules that structure their count list to novel contexts. A total of N = 86 children (3;0 – 6;11) completed a battery of tasks aimed at measuring their understanding of the English count list: they counted as high as they could, and were asked to generate successors to English numbers (e.g., “Fifty-seven: what comes next?”). Next, they were introduced to novel decade terms, and were asked to generate successors to numbers containing those terms (e.g., “Blicky-seven: what comes next?”). Children’s ability to generate successors was predicted by their counting ability, and a sizeable subset of children were able to generate successors both for novel numbers and for English numbers outside their productive count range. These data suggest that emerging counters can use their understanding of the structure of the English count list to generate successors to unfamiliar numbers.

Are there cognitive connections between humans' ability to make music and their understanding of math and numbers? This question has motivated centuries of speculation across the fields of philosophy and education and an increasing number of empirical studies of the topic. We review research at the intersection of numerical and music cognition, and establish its relevance both to the applied sphere (e.g., education) and to core theoretical issues in the cognitive sciences. Next, we identify notable limitations within the literature, and attempt to explain some of the likely causes of-and solutions to-these limitations. Finally, we propose specific themes of focus (spatialization and the mapping between symbolic and nonsymbolic representations) for future research aimed at understanding whether there is shared cognitive architecture for reasoning about number and math.

Researchers from a range of disciplines emphasize that effectively socializing children about race and racism is vital to promoting positive outcomes, such as disrupting the development of racist attitudes and beliefs. While parents and guardians influence children's racial attitudes and beliefs, children also learn about race and racism from many other important adults in their lives, such as teachers, community leaders, and librarians. Yet race-related topics are largely absent or underdeveloped from child-facing programming, policies, and procedures. In this paper, we describe three major barriers to effectively socializing children about race and racism within child-facing institutions like libraries, museums, and schools: (1) adults’ (often inaccurate) beliefs about children's social and cognitive race-related development, (2) adults’ knowledge and comfort discussing race and racism with others, and (3) social norms that minimize explicit discussion of race and racism in institutional and interpersonal contexts. To contextualize these barriers, we address how children can process and reason about race across childhood and outline the evidence-based benefits of socializing children about race and racism inside and outside the home. Finally, we provide recommendations aimed at translating this research to child-focused spaces and provide general guidelines to consider when implementing such practices in their own spheres of influence. In sum, we argue that effective socialization about race and racism benefits all children and can (and should!) be achieved successfully outside of the home; and that adults who interact with children must interrogate their own beliefs, biases, and perspectives, work to develop cultural competence, and invest in and continually reassess practices and policies to facilitate effective socialization about race and racism.

Which factors shape adults' perceptions of the appropriateness of child-facing messaging about race? In an online survey, U.S. adults (N = 715 Black; N = 780 White; Mage = 47 y; 60% parents) read an interaction between a hypothetical parent and their child. The hypothetical child was described as a [Black/White] [5/13]-year-old. The parent conveyed either race-homogenizing (e.g. minimizing racial differences), multicultural (e.g. valuing racial diversity), or structural fairness (e.g. connecting fairness to laws) messaging about race. Participants perceived all of the messages to be appropriate (i.e. above the midpoint of the scale). Generally, Black participants rated messages as more appropriate than White participants, and participants rated all messages as more appropriate for 13-year-olds than 5-year olds. These effects were largest for messages that connected laws to fairness (i.e. structural fairness). There were few effects of the target child's race, including no target child race interactions.

Researchers from a range of disciplines emphasize that effectively socializing children about race and racism is vital to promoting positive outcomes, such as disrupting the development of racist attitudes and beliefs. While parents and guardians influence children's racial attitudes and beliefs, children also learn about race and racism from many other important adults in their lives, such as teachers, community leaders, and librarians. Yet race‐related topics are largely absent or underdeveloped from child‐facing programming, policies, and procedures. In this paper, we describe three major barriers to effectively socializing children about race and racism within child‐facing institutions like libraries, museums, and schools: (1) adults’ (often inaccurate) beliefs about children's social and cognitive race‐related development, (2) adults’ knowledge and comfort discussing race and racism with others, and (3) social norms that minimize explicit discussion of race and racism in institutional and interpersonal contexts. To contextualize these barriers, we address how children can process and reason about race across childhood and outline the evidence‐based benefits of socializing children about race and racism inside and outside the home. Finally, we provide recommendations aimed at translating this research to child‐focused spaces and provide general guidelines to consider when implementing such practices in their own spheres of influence. In sum, we argue that effective socialization about race and racism benefits all children and can (and should!) be achieved successfully outside of the home; and that adults who interact with children must interrogate their own beliefs, biases, and perspectives, work to develop cultural competence, and invest in and continually reassess practices and policies to facilitate effective socialization about race and racism.

How do children form beliefs about the infinity of space, time, and number? We asked whether children held similar beliefs about infinity across domains, and whether beliefs in infinity for domains like space and time might be scaffolded upon numerical knowledge (e.g., knowledge successors within the count list). To test these questions, 112 U.S. children (aged 4;0-7;11) completed an interview regarding their beliefs about infinite space, time, and number. We also measured their knowledge of counting, and other factors that might impact performance on linguistic assessments of infinity belief (e.g., working memory, ability to respond to hypothetical questions). We found that beliefs about infinity were very high across all three domains, suggesting that infinity beliefs may arise early in development for space, time, and number. Second, we found that-across all three domains-children were more likely to believe that it is always possible to add a unit than to believe that the domain is endless. Finally, we found that understanding the rules underlying counting predicted children's belief that it is always possible to add 1 to any number, but did not predict any of the other elements of infinity belief.

The COVID-19 pandemic has forced children to reckon with the causal relations underlying disease transmission. What are children’s theories of how COVID-19 is transmitted? And how do they understand the relation between COVID-19 susceptibility and the need for disease-mitigating behavior? We explored these questions in the context of children’s beliefs about supernatural beings, like Santa and the Tooth Fairy. Because these beings cannot be observed, children’s beliefs about the impact of COVID-19 on them must be based on their underlying theories of disease transmission and prevention rather than on experience. In Summer of 2020, N = 218 U.S. children between the ages of 3 and 10 (M = 81.2 months) were asked to rate supernatural beings’ susceptibility to COVID-19, and the extent to which these beings should engage in disease-mitigating behaviors, such as social distancing and mask wearing. Many children believed supernatural beings were susceptible to COVID-19. However, children rated the need for supernatural beings to engage in disease-mitigating behaviors as higher than the beings’ disease susceptibility, indicating a disconnect between their conceptions of the causal relations between disease-mitigating behavior and disease prevention. Children’s belief that a particular supernatural being could be impacted by COVID-19 was best predicted by the number of human-like properties they attributed to it, regardless of the child’s age. Together, these findings suggest that although young children fail to appreciate specific pathways of disease transmission, they nonetheless understand disease as a bodily affliction, even for beings whose bodies have never been observed.

Anti-racist efforts require talking with children about race. The present work tested the predictors of U.S. adults' ( N  = 441; 52% female; 32% BIPOC participants; M age  = 35 years) conversations about race with children across two timepoints in 2019. Approximately 60% of adult participants talked to their children (3–12 years) about race during the preceding week; only 29% talked to other adults about race during the same period. This paper describes the content and predictors of conversations about race, revealing how conversations differ depending on the participant's race, a child's age, and whether the conversation occurs with children or another adult. These data have important implications for theorizing about when, why, and how adults actually talk about race with children and adults.

Anti-racist efforts require talking with children about race. The present work tested the predictors of U.S. adults' (N = 441; 52% female; 32% BIPOC participants; Mage  = 35 years) conversations about race with children across two timepoints in 2019. Approximately 60% of adult participants talked to their children (3-12 years) about race during the preceding week; only 29% talked to other adults about race during the same period. This paper describes the content and predictors of conversations about race, revealing how conversations differ depending on the participant's race, a child's age, and whether the conversation occurs with children or another adult. These data have important implications for theorizing about when, why, and how adults actually talk about race with children and adults.

Yarkoni’s analysis clearly articulates a number of concerns limiting the generalizability and explanatory power of psychological findings, many of which are compounded in infancy research. ManyBabies addresses these concerns via a radically collaborative, large-scale and open approach to research that is grounded in theory-building, committed to diversification, and focused on understanding sources of variation.

Gender stereotypes shape individuals' behaviors, expectations, and perceptions of others. However, little is known about the content of gender stereotypes about people of different ages (e.g., do gender stereotypes about 1-year-olds differ from those about older individuals?). In our pre-registered study, 4,598 adults rated either the typicality of characteristics (to assess descriptive stereotypes), or the desirability of characteristics (to assess prescriptive and proscriptive stereotypes) for targets who differed in gender and age. Between-subjects, we manipulated target gender (boy/man vs. girl/woman) and target age (1, 4, 7, 10, 13, 16, or 35). From this, we generated a normed list of descriptive, prescriptive, and proscriptive gender-stereotyped characteristics about people across the early developmental timespan. We make this archive, as well as our raw data, available to other researchers. We also present preliminary findings, demonstrating that some characteristics are consistently ungendered (e.g., challenges authority), others are gender-stereotypic across the early developmental timespan (e.g., males from age 1 to 35 tend to be dirty), and still others change over development (e.g., girls should be submissive, but only around age 10). Implications for gender stereotyping theory-as well as targets of gender stereotyping, across the lifespan-are discussed.

Understanding symbols requires going beyond what they literally are, and figuring out what they're intended to communicate. For example, a drawing of a bird (or the word bird) could refer to a particular bird, a species, etc… The interpreter must decide between these intended meanings. We ask how children go beyond the literal meanings of communicative acts (i.e., compute pragmatic inferences), and whether these inferences are domain-general. We tested 443 US 2- to 6-year-olds' inferences about the referential interpretation of ambiguous symbols. We manipulated the domain (e.g., word or a drawing) and task (interpret vs. create the communicative act). Children robustly identified the referents of ambiguous symbols and chose from among alternatives during linguistic and non-linguistic communication tasks. There were no effects of age or domain on performance. These data provide some of the earliest evidence of children's computations of pragmatic inferences, and provide exciting evidence that pragmatic inferences may extend beyond the domain of language.

To help children navigate their social environments, adults must understand what children know about race, and when they acquire this knowledge. Across three pre-registered studies, we tested US adults’ knowledge of when children first use race to categorize and ascribe traits to others. Participants wildly—and uniquely—misjudged children’s abilities to process race. This inaccuracy was consequential: it was a stronger predictor of the preference to delay conversations about race with children than other factors previously theorized to underlie adults’ reluctance to talk about race. And, this relation was causal. Our data suggest that fundamental misunderstandings about children’s capacities to process race are pervasive in the US population and may delay when adults engage children in important conversations about race.

Although many US children can count sets by 4 years, it is not until 5½-6 years that they understand how counting relates to number - i.e., that adding 1 to a set necessitates counting up one number. This study examined two knowledge sources that 3½-6-year-olds (N = 136) may leverage to acquire this “successor function”: (1) mastery of productive rules governing count list generation; and (2) training with “+1” math facts. Both productive counting and “+1” math facts were related to understanding that adding 1 to sets entails counting up one number in the count list; however, even children with robust successor knowledge struggled with its arithmetic expression, suggesting they do not generalize the successor function from “+1” math facts.

We introduce a new resource: the SAYCam corpus. Infants aged 6-32 months wore a head-mounted camera for approximately 2 hours per week, over the course of approximately two and a half years. The result is a large, naturalistic, longitudinal dataset of infant- and child-perspective videos. Over 200,000 words of naturalistic speech have already been transcribed. Similarly, the dataset is searchable using a number of criteria (e.g., age of participant, location, setting, objects present). The resulting dataset will be of broad use to psychologists, linguists, and computer scientists.

Although many U.S. children can count sets by 4 years, it is not until 5½–6 years that they understand how counting relates to number—that is, that adding 1 to a set necessitates counting up one number. This study examined two knowledge sources that 3½- to 6-year-olds ( N  = 136) may leverage to acquire this “successor function”: (a) mastery of productive rules governing count list generation; and (b) training with “+1” math facts. Both productive counting and “+1” math facts were related to understanding that adding 1 to sets entails counting up one number in the count list; however, even children with robust successor knowledge struggled with its arithmetic expression, suggesting they do not generalize the successor function from “+1” math facts.