Emergent and constrained: understanding brain and cognitive development

The process by which neural structures and cognitive functions arise through manifold local interactions (emergence) is at the core of many neurocognitive frameworks (as reviewed by Hernandez et al., 2018). However, the emergence of neural structures and cognitive processes is not unconstrained; it is context dependent. Therefore, to truly understand brain and behaviour, it is necessary to identify the contexts or factors that interact to constrain the emergence of higher-level neurocognitive processes and behaviour (Mareschal et al., 2007; Thelen & Smith, 1994; Waddington, 1957). It is also important to understand how these factors interact over different timescales (Gottleib, 1992). We illustrate these points using examples from language development, and conclude by arguing that specifying the processes that constrain emergence is the key to understanding brain and cognition