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Previously, research on wishful thinking has found that desires bias older children's and adults' predictions during probabilistic reasoning tasks. In the present paper, we explore wishful thinking in children aged 3-to 10years-old. Do young children learn to be wishful thinkers? Or do they begin with a wishful thinking bias that is gradually overturned during development? Across 5 experiments, we compare low-and middle-income U.S. and Peruvian 3-to 10-year-old children (N=682). Children were asked to make predictions during games of chance. Across experiments, preschool aged children from all backgrounds consistently displayed a strong wishful thinking bias. However, the bias declined with age.

Extensive research has explored the ability of young children to learn about the causal structure of the world from patterns of evidence. These studies, however, have been conducted with middle-class samples from North America and Europe. In the present study, low-income Peruvian 4-and 5-year-olds and adults, low-income U.S. 4-and 5-year-olds in Head Start programs, and middle-class children from the U.S. participated in a causal learning task (N = 435). Consistent with previous studies, children learned both specific causal relations and more abstract causal principles across culture and socioeconomic status (SES). The Peruvian children and adults generally performed like middle-class U.S. children and adults, but the low-SES U.S. children showed some differences. CAUSAL LEARNING ACROSS CULTURE AND SES 3 Causal learning across culture and socioeconomic statusComing to understand the causal structure of the world is a central part of cognitive and conceptual development. Causal learning plays an especially important role in the development of intuitive theories of the world, such as folk biology and "theory of mind". In the past fifteen years, there has been a large body of research showing how computational systems can accurately infer causal relations from statistical patterns of data (e.g. Spirtes, Glymour, & Scheines,1993;Pearl, 2009;Tenenbaum, Kemp, Griffiths, & Goodman, 2011). There have also been hundreds of causal learning experiments with toddlers and preschoolers, coming from a number of different laboratories (see Gopnik &Wellman 2012; Xu & Kushnir, 2012 for recent reviews). These studies show remarkably high levels of competence in young children. In fact, some recent causal learning studies have yielded a counterintuitive pattern of findings: the ability to infer certain types of abstract causal relations from evidence actually appears to decline with age, so that younger children do better than older children and adults (Gopnik, Griffiths, & Lucas, 2015;Lucas, Bridgers, Griffiths, & Gopnik, 2014; Seiver, Gopnik & Goodman, 2013, Gopnik et al. in press).However, to our knowledge, these studies have all examined children in similar middleto upper-class samples in North America and Europe-i.e., children from WEIRD (Western, educated, industrial, rich, and democratic) cultures (Henrich, Heine, & Norenzayan, 2010). There has been important cross-cultural work on the development of intuitive theories (e.g. Avis & Harris, 1991;Callaghan et al, 2005;Coley 2012;Gelman & Legare, 2011;Medin & Atran, 2004;Wellman et al. 2006), but not on the causal learning abilities that might help underpin this development. CAUSAL LEARNING ACROSS CULTURE AND SES 4In the current paper, we extend research on causal learning to two very different types of populations: a cross-cultural sample of relatively low-income Peruvian children and adults and a cross-socioeconomic sample of children from low-income North American families. There is increasing recognition of the importance of including a wider range of particip...

Pragmatic reasoning – the ability to infer the intended meaning of an utterance in context – is one of the core aspects of language comprehension. Yet classic linguistic accounts of pragmatics may not apply as consistently in non-WEIRD (western, educated, industrialized, rich, democratic) contexts. Children’s ability to reason pragmatically increases across childhood in U.S. and European communities. Ad hoc (contextual) implicatures tend to emerge around age four, but this pattern has not been studied cross-culturally. We conducted a study of the development of ad-hoc implicatures in Shipibo-Konibo communities in the Peruvian Amazon – a culture with a holistic orientation that might be expected to lead to a decrease in the felicity of implicatures, inferences which typically lead to restrictions on context. While 8–10 year-olds successfully made these implicatures, younger children did not, despite successfully understanding control trials. These findings suggest that ad-hoc implicatures are available interpretations, even in a community with different cultural expectations, but that their development may be more protracted.

Pretend play universally emerges during early childhood and may support the development of causal inference and counterfactual reasoning. However, the amount of time spent pretending, the value that adults place on pretence and the scaffolding adults provide vary by both culture and socioeconomic status (SES). In middle class U.S. preschoolers, accuracy on a pretence-based causal reasoning task predicted performance on a similar causal counterfactual task. We explore the relationship between cultural environment, pretence and counterfactual reasoning in low-income Peruvian ( N = 62) and low-income U.S. ( N = 57) 3- to 4-year olds, and contrast findings against previous findings in an age-matched, mixed-SES U.S. sample ( N = 60). Children learned a novel causal relationship, then answered comparable counterfactual and pretence-based questions about the relationship. Children's responses for counterfactual and pretence measures differed across populations, with Peruvian and lower-income U.S. children providing fewer causally consistent responses when compared with middle class U.S. children. Nevertheless, correlations between the two measures emerged in all populations. Across cohorts, children also provided more causally consistent answers during pretence than counterfactually. Our findings strengthen the hypothesis that causal pretend play is related to causal counterfactual reasoning across cultural contexts, while also suggesting a role for systematic environmental differences. This article is part of the theme issue ‘Thinking about possibilities: mechanisms, ontogeny, functions and phylogeny’.