Browsing by Subject "Behavior genetics"

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    Free will, determinism, and intuitive judgments about the heritability of behavior
    (2019-09) Willoughby, Emily
    The fact that genes and environment contribute differentially to variation in human behaviors, traits and attitudes is central to the field of behavior genetics. Perceptions about these differential contributions may affect ideas about human agency. We surveyed two independent samples (N = 301 and N = 740) to assess beliefs about free will, determinism, political orientation, and the relative contribution of genes and environment to 21 human traits. We find that lay estimates of genetic influence on these traits cluster into four distinct groups, which differentially predict beliefs about human agency, political orientation, and religiosity. Despite apparent ideological associations with these beliefs, the correspondence between mean lay estimates and published heritability estimates for the surveyed traits is large (r = .77). Belief in genetic determinism emerges as a modest predictor of accuracy in these lay estimates. Additionally, educated mothers with multiple children emerge as particularly accurate in their estimates of the genetic contribution to these traits.
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    Tracing causes and consequences of human intelligence through genetic and cognitive data
    (2020-12) Willoughby, Emily
    The work included in this dissertation represents empirical inquiries into three areas of cause and consequence for individual differences in human intelligence: How molecular genetic data can be used to draw inference about environmental mechanisms, how intelligence relates to information processing in the brain, and whether intelligence is meaningfully malleable by parental influence into adulthood. Study 1 uses polygenic scores derived from a large GWAS of educational attainment to demonstrate “genetic nurture”, through which the unique genetics of parents can give rise to passive gene-environment correlation that affects their offspring’s years of education. Study 2 explores the observation that faster reaction time (RT) on elementary cognitive tasks (ECTs) is associated with higher g. By partitioning stimuli into perceptual and decisional stages of information flow, we show through both additive-factors logic and diffusion modeling that g is expressed uniquely in the decisional, but not perceptual, stage of processing. Finally, Study 3 examines the sources of variance in IQ in a fully adult sample of adoptive and biological families to provide new evidence about the extent of IQ’s malleability. We find that the environment fostered by the parents explains less than 3% of the variance in their offspring’s IQ scores in adulthood. In sum, the converging operations afforded by twin and adoption studies, GWAS, and ECTs can address crucial questions of causal inference in human intelligence.