Assessing Early Changes in Executive Functions: Working Memory, Shifting, and Inhibition in 22-, 24-, and 26-month-olds

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

Abstract

Myake et al. (2000) identified working memory, shifting, and response inhibition as separate but related factors of executive function. EFs are known to predict later life success, but we still know only little about how they first emerge in toddlerhood. In this study, we use an EF task battery introduced by Pauen & Bechtel-Kuehne (2016) to probe EF in two-year-olds, and check whether earlier findings can be replicated based on a larger sample.

Working memory: N = 178 children (22-months: 45; 24-months: 68; 26 months: 65)searched for a toy previously hidden in one of multiple boxes placed in a row (hiding position varying between trials). The number of boxes (3 or 6) and the waiting time before starting to search (5s or 8s) increased across phases A to D of the experiment, including 3 trials each. A significant age difference in the number of correct trials was found, (H(2) = 10.51, padj = .025), and post hoc tests revealed that 22- and 24-month-olds’ performance exceeded that of 26-month-olds during the first phase only (3 boxes, 5s delay), presumably because older toddlers showed more explorative behavior. Otherwise performance was largely comparable across age-groups, thus replicating previous findings.

Response inhibition: N = 167 children (22-months: 49; 24-months: 62; 26 months: 56) were asked to refrain from touching a bowl of cookies placed within their reach until the experimenter returned after 2 minutes. Consistent with Pauen & Bechtel-Kuehne (2016), the mean waiting time increased from 28s in 22-month-olds, over 45s in 24-month-olds to 80s in 26-month-olds, thus showing a strong age-effect (χ2(2) = 27.99; p < .001; see also Figure 1).

Shifting: N = 156 children (22-months: 41; 24-months: 58; 26 months: 57) sorted (a) round and square-shaped forms of white color into yellow and green boxes matching the shape of the forms (pre-switch-phase), (b) yellow and green forms according to their color into the same boxes (post-switch-phase 1), and (c) the same forms according to shape again (post- switch-phase 2). Figure 2 presents the material. The experimenter provided feedback on every trial. Only children sorting 5 out of 6 forms correctly on the pre-switch phase were considered for further analyses (22-months: 17; 24-months: 41; 26 months: 42). Performance increased with age, (H(2) = 8.36; padj = .045), mainly due to the fact that 26- month-olds reached higher scores than 24-month-olds, z = -2.73; padj = .019, r = .30, thus replicating earlier findings.

In sum, results regarding all 3 EF tasks replicate those of Pauen & Bechtel-Kuehne (2016), suggesting that EF performance can be assessed reliably in young toddlers. Whereas success rates did not increase systematically with age in the working memory task, substantial developmental changes could be observed regarding response inhibition and shifting between 24 and 26 months of age. No significant inter-task correlations were found.
Implications for the early development of EF will be discussed in the talk.

Authors

• Sabina M Pauen, Ruprecht-Karls-Universität Heidelberg
  Presenting Author

• Philipp Horrer, University of Heidelberg
  Non-Presenting Author