Development of Inhibitory Control across the Second Year

• In Event: The Development of Executive Functions in Early Toddlerhood

Abstract

Of all the executive functions, inhibitory control (IC) may be the most critical in early development. Early IC abilities predict cognitive, academic, and socio-emotional outcomes in childhood and adolescence (Blair & Razza, 2007; Carlson & Wang, 2007). Although there is disagreement as to the specific nature of IC (Munakata et al., 2011; Nigg, 2000), its value for optimal development is undisputed. Diamond (2013) proposes a parsimonious view of IC during early development, with two main types of IC: interference control and self-control/response inhibition (related to later developing self-discipline). Cognitive inhibition is a subtype of interference control focused on the suppression of previously acquired information and memories. Response inhibition involves resisting temptations and resisting impulsive actions. These types of IC are foundational for developing self-regulation and are widely studied in early childhood, but we know little about their development prior to the 3rd birthday. We focused on the development of IC during the second year, when developmental changes in multiple aspects of self-regulation are rapidly occurring, because we wanted to track developmental changes in two types of IC and determine if the patterns of development were similar or disparate. In adults, both cognitive IC and response inhibition are associated with various frontal networks (Diamond, 2013); thus, we hypothesized that the developmental patterns of these types of IC would be similar across the second year, with each showing a progressive increase in performance.

Thirty-eight typically developing toddlers (half girls) and their parents were seen in the research lab at 15, 18, 21, and 24 months. At each lab visit experimenters administered a cognitive IC task (looking A-not-B task with invisible displacement; Diamond et al., 1997) and a response inhibition task (glitter wand “don’t touch” task; Friedman et al., 2012).

Figure 1 shows percentage correct performance across age on the cognitive IC task. Performance on the inhibitory trials (reversal or “B” trials) showed development across age (Wilks’ = .88, p = .002); however, performance on the non-inhibitory trials (original or “A” trials) did not change (Wilks’ Lambda = .456, p=.308). The greatest change in development for the inhibitory trials was between 21 and 24 months. Figure 2 shows latency to touch across age on the prohibition task (Wilks’ = .67, p < .001). As with the cognitive IC task, the greatest change in development was between 21 and 24 months. When examining the number of children who did not touch the prohibited glitter wand, there were 3, 7, 6, and 14 children at 15, 18, 21, and 24 months, respectively.

These data show development of two different types of IC (cognitive IC, a type of interference control; and self-control/response inhibition) during the second year. These data also highlight what appears to be a critical development shift between 21 and 24 months, unlike our progressive increase hypothesis. This work fills critical gaps in our scientific knowledge regarding normal trajectories of early IC development during toddlerhood.

Authors

• Martha Ann Bell, Virginia Polytechnic Institute and State University
  Presenting Author

• Leslie A. Patton, Virginia Tech
  Non-Presenting Author

• Ran Liu, Columbia University
  Non-Presenting Author

• Tatiana Meza-Cervera, Virginia Polytechnic Institute and State University
  Non-Presenting Author

• Madeleine Diane Bruce, University of Utah
  Non-Presenting Author