Development is a complex interaction between genes, the environment, and past development (Sroufe, 2013). Neural development, specifically, is known to be an experience-dependent process (Greenough, Black, & Wallace, 1987), and early life experiences can have powerful effects on the developing brain (Fox, Levitt, & Nelson, 2010; Meaney & Szyf, 2005). Further, the relations between neural activity and the genetic processes that regulate it are now known to be bidirectional (Grossman, Churchill, McKinney, Kodish, Otte, & Greenough, 2003). Thus, a complete understanding of the processes driving neural and cognitive development requires incorporating elements of both individual capacities and environmental conditions into research models. One limitation of the current study was that it exclusively focused on intrinsic processes. However, extrinsic influences, most notably the caregiving environment, on the development of attention (Swingler, Perry, & Calkins, 2015) and cognition (Cuevas, Deater-Deckard, Kim-Spoon, Watson, Morasch, & Bell, 2014) have been noted. Although studies are beginning to expand on this basic model to include extrinsic influences on early neural maturation, attention, and cognition (Bernier, Calkins, & Bell, in press), many more are needed.
