Two extant frameworks – the harshness-unpredictability model and the threat-deprivation model – attempt to explain which dimensions of adversity have distinct influences on development. These models address, respectively, why, based on a history of natural selection, development operates the way it does across a range of environmental contexts, and how the neural mechanisms that underlie plasticity and learning in response to environmental experiences influence brain development. Building on these frameworks, we advance an integrated model of dimensions of environmental experience, focusing on threat-based forms of harshness, deprivation-based forms of harshness, and environmental unpredictability. This integrated model makes clear that the why and the how of development are inextricable and, together, essential to understanding which dimensions of the environment matter. Core integrative concepts include the directedness of learning, multiple levels of developmental adaptation to the environment, and tradeoffs between adaptive and maladaptive developmental responses to adversity. The integrated model proposes that proximal and distal cues to threat-based and deprivation-based forms of harshness, as well as unpredictability in those cues, calibrate development to both immediate rearing environments and broader ecological contexts, current and future. We highlight actionable directions for research needed to investigate the integrated model and advance understanding of dimensions of environmental experience.

现有的两个框架——严酷-不可预测性模型和威胁-剥夺模型——试图解释逆境的哪些维度对发展有不同的影响。这些模型分别阐述了为什么基于自然选择的历史，发育在一系列环境背景下以这种方式运作，以及作为可塑性和学习响应环境经验的基础的神经机制如何影响大脑发育。在这些框架的基础上，我们提出了环境体验维度的综合模型，重点关注基于威胁的严酷形式、基于剥夺的严酷形式以及环境的不可预测性。这个综合模型清楚地表明，发展的原因和方式是密不可分的，而且对于理解环境的哪些方面很重要至关重要。核心综合概念包括学习的定向性、对环境的多层次发展适应，以及对逆境的适应性和适应不良发展反应之间的权衡。该综合模型提出，基于威胁和基于剥夺的严酷形式的近端和远端线索，以及这些线索的不可预测性，可以根据当前和未来的直接饲养环境和更广泛的生态环境来校准发展。我们强调了调查综合模型和增进对环境体验维度的理解所需的可行研究方向。