Efficiently processing information from faces in infancy is foundational for nonverbal communication. We studied individual differences in 5-month-old infants' (N = 517) sustained attention to faces and preference for emotional faces. We assessed the contribution of genetic and environmental influences to individual differences in these gaze behaviors, and the association between these traits and other concurrent and later phenotypes. We found an association between the mean duration of looking at a face (before looking away from it) at 5 months and socio-communicative abilities at 14 months (β = 0.17, 95% CI: 0.08; 0.26, p < 0.001). Sustained attention to faces predicted socio-communicative abilities over and above variance captured by mean fixation duration. We also found a statistically significant but weak tendency to prefer looking at smiling faces (relative to neutral faces), but no indication that variability in this behavior was explained by genetic effects. Moderate heritability was found for sustained attention to faces (A = 0.23, CI: 0.06; 0.38), while shared environmental influences were non-significant for both phenotypes. These findings suggest that sustained looking at individual faces before looking away is a developmentally significant ‘social attention’ phenotype in infancy, characterized by moderate heritability and a specific relation to later socio-communicative abilities.

中文翻译：

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5 个月大时持续看脸与第二年的社交沟通能力有关

在婴儿期有效处理来自面部的信息是非语言交流的基础。我们研究了 5 个月大婴儿 ( N  = 517) 对面孔的持续关注和对情绪面孔的偏好的个体差异。我们评估了遗传和环境影响对这些凝视行为个体差异的贡献，以及这些特征与其他同时发生和后来的表型之间的关联。我们发现 5 个月时看脸的平均持续时间（在移开目光之前）与 14 个月时的社交沟通能力之间存在关联（β  = 0.17，95% CI：0.08；0.26，p  < 0.001）。对面部的持续关注可以预测社交沟通能力，而这超出了平均注视持续时间捕获的方差。我们还发现了一种统计上显着但微弱的倾向，即更喜欢看笑脸（相对于中性面孔），但没有迹象表明这种行为的变异性可以用遗传效应来解释。对面孔的持续关注具有中等遗传力（A  = 0.23，CI：0.06；0.38），而共同的环境影响对两种表型都不显着。这些发现表明，在看向别处之前持续注视个别面孔是婴儿期一种具有重要发育意义的“社会注意力”表型，其特征是中等遗传力以及与后来的社会沟通能力的特定关系。