Scott Alexander admits he was wrong about preschool programs like Head Start, discussing new evidence of their long-term benefits and considering the implications for understanding environmental effects and policy. Longer summary

Scott Alexander reflects on his previous skepticism about the effectiveness of preschool programs like Head Start, admitting he was wrong based on new evidence. The post discusses research showing that while preschool doesn't improve academic skills or IQ, it does lead to better long-term life outcomes such as staying in school longer, getting better jobs, and committing less crime. Scott speculates that these benefits might stem from social factors like freeing up parents' time or exposing children to different environments. He also grapples with how this conflicts with studies showing little impact of shared environment on outcomes, and considers implications for policy support of universal childcare or pre-K programs. Shorter summary

Scott Alexander discusses a study challenging the idea that childhood abuse lowers IQ, and explores its implications for understanding the effects of child abuse on various outcomes. Longer summary

This post discusses a study by Danese et al. challenging the assumption that childhood abuse lowers IQ. The study found that after adjusting for pre-existing factors, there was no significant difference in IQ between abused and non-abused children. Scott Alexander explores the implications of this study in the context of shared-environment-skeptical psychiatry and discusses other studies showing limited effects of child abuse on various outcomes. He notes that while these findings are interesting, they may understate the dangers of severe abuse due to sample size limitations. The post concludes by suggesting that child abuse likely causes PTSD-like symptoms but may not have effects drastically different from normal PTSD. Shorter summary

The author revisits their belief in genetic determinism, presenting evidence that environmental factors, especially in divorce, have significant non-genetic effects on children's outcomes. Longer summary

The post discusses the author's initial belief in the genetic determinism thesis from 'The Nurture Assumption', which argues that parenting has little effect on children's outcomes compared to genetics. The author then presents evidence from divorce studies that challenge this view, showing that environmental factors, particularly family conflict, do have significant effects on children. The post reviews several studies that disentangle genetic and environmental effects of divorce, concluding that there are indeed non-genetic negative impacts of divorce on children. The author acknowledges being wrong about shared environment effects being negligible and suggests that short-term environmental impacts can have long-lasting consequences. Shorter summary