There is an open secret in the study of child development: Most of what we think we know about how babies develop is actually based on a specific subset of kids—those born to families from Western, educated, industrialized, rich, and democratic (a.k.a. WEIRD) nations. The acronym was first coined in an influential 2010 paper to describe the wildly unrepresentative populations that many psychology studies have long relied on. This is an issue in the field generally, and certainly a thorny problem in developmental psychology, which primarily studies children: According to one paper, WEIRD subjects make up 96 percent of the data used in published developmental-science studies but represent only 12 percent of the world’s population.
As a result, it’s hard to be certain whether many things we think we know about babies’ development are truly universal elements of human nature. It means that we tell an incomplete story about the process of our own becoming. Yet the problem has remained hard to fix. Even within the U.S., similar demographic biases have arisen: The families that most often participate in research studies tend to be white, affluent, and highly educated. The type of parent who brings their baby to a study typically lives near a university, many of which are located in cities, and has the resources and free time to travel to a lab and wait. “Some labs can book a single baby for a day” to collect one data point, Elizabeth Bonawitz, a cognitive scientist at Harvard, told me.
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