Relations between Parent Reports of Effortful Control and Behavioral Measures of Executive Function in Toddlers

University of Mississippi University of Mississippi

eGrove eGrove

Honors Theses

Honors College (Sally McDonnell Barksdale

Honors College)

Spring 5-9-2024

Relations between Parent Reports of Effortful Control and Relations between Parent Reports of Effortful Control and

Behavioral Measures of Executive Function in Toddlers Behavioral Measures of Executive Function in Toddlers

Racheal Embry

Follow this and additional works at: https://egrove.olemiss.edu/hon_thesis

Part of the Child Psychology Commons, Cognitive Psychology Commons, and the Developmental

Psychology Commons

Recommended Citation Recommended Citation

Embry, Racheal, "Relations between Parent Reports of Effortful Control and Behavioral Measures of

Executive Function in Toddlers" (2024).

Honors Theses

. 3058.

https://egrove.olemiss.edu/hon_thesis/3058

This Undergraduate Thesis is brought to you for free and open access by the Honors College (Sally McDonnell

Barksdale Honors College) at eGrove. It has been accepted for inclusion in Honors Theses by an authorized

administrator of eGrove. For more information, please contact [email protected].

RELATIONS BETWEEN PARENT REPORTS OF EFFORTFUL CONTROL AND

BEHAVIORAL MEASURES OF EXECUTIVE FUNCTION IN TODDLERS

Racheal A. Embry

A thesis submitted to the faculty of The University of Mississippi in partial fulfillment of the

requirements of the Sally McDonnell Barksdale Honors College.

Oxford

2024

Approved by:

____________________________

Advisor: Dr. Stephanie Miller

____________________________

Reader: Dr. John Young

____________________________

Reader: Dr. Teresa Lefmann

Racheal A. Embry

ACKNOWLEDGMENTS

I would like to extend my appreciation to the Sally McDonnel Barksdale Honors College

and the National Institute of Health for their financial support of this project. I would also like to

offer my sincerest appreciation to Dr. Stephanie Miller for her unending support of my work as a

student and researcher and her willingness to answer the plethora of questions I have had along

the way. Finally, I would like to thank my family and friends who have encouraged me and

offered their unwavering support over the past two years as I have worked on this project.

ABSTRACT

Racheal A. Embry: Relations between Parent Reports of Effortful Control and Behavioral

Measures of Executive Function in Toddlers (Under direction of Stephanie Miller)

Recent proposals have identified many commonalities in conceptualizations of effortful control

and executive function (EF, e.g., Zhou, Chen, & Main, 2012). However, the overlap of effortful

control and EF during periods of emerging regulation in toddlerhood has not been thoroughly

investigated. In the present study, I examined the relationship between effortful control and EF in

14, 18, and 24 month old toddlers by a combination of in-lab tasks and parent report measures.

Results revealed few relations between effortful control and EF during this time. The lack of

overlap between effortful control and EF may be explained by a number of factors including

differences in method of measurement and the rapid development of self regulatory behaviors

during this age group.

Keywords: Effortful Control, Executive Function

TABLE OF CONTENTS

LIST OF TABLES AND FIGURES ……………………………………………………………..6

INTRODUCTION………………………………………………………………………………...7

THE PRESENT STUDY………………………………………………………………………...15

METHODS………………………………………………………………………………………15

RESULTS………………………………………………………………………………………..24

DISCUSSION……………………………………………………………………………………27

WORKS CITED…………………………………………………………………………………30

LIST OF TABLES AND FIGURES

FIGURE 1………………………………………………………………………………………..18

TABLE 1…………………………………………………………………………………………25

TABLE 2…………………………………………………………………………………………26

The examination of self-regulation is fundamental to understanding development across

multiple domains, justifying its identification as a cornerstone of early child development

(Shonkoff et al., 2000). Research suggests that evidence of self-regulatory behaviors begin

developing during toddlerhood and into the preschool years (Schmidt, 2021; Kochanska, 2001).

However, the examination of self-regulation is broad, encompassing a collection of functions

related to individual control over thought and action. This has led to a number of separate

constructs, often focused on very similar abilities but based in different developmental

literatures. The present paper examined two constructs within self-regulation—effortful control

and executive function (EF)—that originated from two different developmental literatures but

have been proposed to measure similar abilities (Zhou et al., 2012). Explorations of the relations

between these constructs are rare, especially in the toddler years which many have suggested is a

foundational period for the development of self regulation (Miller et al., 2015; Garon et al.,

2008; Isquith et al., 2005; Best et al., 2010). . Thus, the goal of the present work is to explore the

commonalities and differences between EF and effortful control at 14-, 18-, and 24- months of

age.

Theoretical Underpinnings between EF and Effortful Control

Although effortful control and EF are both focused on self-regulation, there are

differences in their conceptualizations. Effortful control is defined as the ability to inhibit

dominant responses necessary to activate less dominant responses, plan, and detect errors

(Kochanska et al., 2000; Rothbart et al., 2007). This construct originated from research on

temperament, which initially focused on uncovering relatively stable individual differences in

infant reactivity and self-regulation, frequently collected through parent reports (e.g., activity

level, orienting, see Rothbart, 1981; Thomas & Chess, 1977). Work extended to the toddler and

childhood years as researchers began to appreciate the role of experience, context, and

developing aspects of cognition (i.e., self-control and attention) in guiding behavior (e.g., Shiner

et al., 2012). This resulted in more toddler- and child-centered effortful control measures

involving voluntary control, such as parent report measures of attentional focus, attentional

shifting, and inhibitory control in 18-month-olds (Putnam et al., 2006). Developmentally,

Rothbart and colleagues proposed a neurological model of effortful control, suggesting that

reactivity in infancy is initially driven by an attentional orienting system that infants have little

control over (e.g., parietal areas and frontal eye fields activated during orienting, see Posner et

al., 2012; Rothbart et al., 2007). By preschool, a later developing executive attention network

(i.e., the anterior cingulate gyrus and lateral prefrontal areas activated during cognitive control) is

responsible for advances in effortful control. EF, on the other hand, is defined as the ability to

regulate behavior consciously toward a goal and is typically measured through behavioral tasks

rather than surveys or parent reports that are common for effortful control(Zelazo et al., 2003).

Although EF focuses on similar inhibitory abilities as effortful control (e.g., Carlson, 2005), EF

also taps into the additional components of working memory (i.e., holding and manipulating

information in mind) and set-shifting (i.e., switching between mental sets, Wiebe et al., 2008;

Wiebe et al., 2011). These component abilities are proposed to share a “common EF”, capturing

the ability to maintain task relevant information and guide lower level processes toward

executing a goal (Miyake & Friedman, 2012). EF emerged out of the cognitive neuroscience

literature with a developmental focus on preschool during which children typically display rapid

development (e.g., Carlson, 2005; Garon et al., 2008), longitudinal stability (e.g., Carlson et al.,

2004; Hughes & Ensor, 2005, 2007) and relations between performance on various behavioral

measures of EF thought to tap into different EF components. Neurological frameworks point to

similar structures implicated in improved effortful control (e.g., development in the prefrontal

cortex and executive attention networks, Garon et al., 2008; Johansson et al., 2015). Further,

accounts have linked these neural processes to neurocognitive skills that involve forming and

reflecting on task-relevant representations necessary to execute pertinent rules (e.g., using

relevant language to represent task problems and help guide behavior activated within the

prefrontal cortex, Zelazo, 2004, 2015). Developmentally, these representational frameworks of

EF suggest that one may trace the origins of a “common EF” to the toddler years with the

development of representation (Miller & Marcovitch, 2015). Thus, research has renewed focus

on the second and third year suggesting that important developments in EF emerge between 12

and 24 months of age (Wiebe et al., 2010)

Potential for Integrating Conceptualizations of EF and Effortful Control

Theoretical Frameworks. Zhou and colleagues (2012) called for an integrated model of

self-regulation bringing together examinations of effortful control and EF, arguing that these

self-regulatory abilities are more similar than different in their examination of component

abilities (e.g., inhibition) and common processes (e.g., attentional mechanisms involved in

conflict monitoring, resolution, and top down processing, see also Bridgett et al., 2015; Bridgett

et al., 2013). Similarly, Nigg (2016) asserted that while effortful control is narrower in scope (i.e.

it does not include complex cognitive strategies such as following sequenced instructions or

predicting future conflicts) than EF, they share many of the same features (e.g., executive

attention) thus likely leading the measures to correlate. Schmidt (2022) argued that EF and

effortful control lack clear separation in some of their measures (e.g., inhibition) and the choice

of which term a researcher uses is based on their developmental approach. Thus, this may lead to

complications, as research findings are not integrated across disciplines. For example, the snack

delay task (i.e., children are asked to wait for a period of time before eating a snack placed in

front of them) has been used to measure both EF and effortful control as the task has been

hypothesized to measure inhibition, working memory, and delay of gratification, subcomponents

of both constructs. They suggest that in order to grasp the similarity and correlative nature of EF

and effortful control, younger ages groups, specifically following the first year of life, should be

the focus of research as EF and effortful control develop rapidly during this time frame. Other

researchers argue that effortful control and EF are not necessarily redundant measures.

Researchers have asserted that unshared elements between the two constructs may allow them to

make distinct contributions to understanding self-regulation (Blair & Razza, 2007; Liew, 2011),

a proposal that aligns with some reseacher’s (Schmidt, 2022; Zhou 2011; Nigg, 2016) suggestion

that integrated models should examine effortful control and EF together to help identify common

and distinct elements (see also Miyake et al., 2000, for a similar approach with componential EF

models). Examples of these unshared elements include differences in measurement, as effortful

control typically examines more “hot” affectively driven control that is measured via parent-

report of how children handle common situations within familiar settings (e.g., when told “no”

how often does your child stop an activity quickly, Putnam et al., 2006). EF focuses on more

“cool” cognitive problems (e.g., Zelazo et al., 2003) measured via behavioral problem-solving

tasks typically within a laboratory setting (but see Zhou et al., 2012). In addition, working

memory is more central to the EF literature (Liew, 2011; Zhou et al., 2012), possibly resulting in

different contributions to self-regulation.

Empirical Examinations of the Relationships Between Effortful Control and Executive

Function

Empirically, there is a growing body of research examining relations between effortful

control and EF across the lifespan. For instance, work with adults demonstrated that measures of

effortful control are related to working memory in EF, suggesting these two constructs share

considerable overlap supporting perspectives of integration (Bridgett et al., 2013; Zhou et al.,

2012). There have also been a number of studies that have examined effortful control-EF

relationships during the first 6 years of life.

Preschoolers

Research involving data from preschool children have found data supporting the theory

of commonalities and relationships between the construct of EF and effortful control. For

example, Kalin (2021) examined children between the ages of 4 and 6 through both parent report

measures (Early Childhood Behavior Questionnaire, ECBQ) and behavioral measures of

effortful control such as the whisper task (children were asked to whisper the names of

characters and were scored based on the number of times they shouted rather than whispered)

and the puzzle box (children were asked to put together a puzzle box without looking at it). This

was compared to measures of working memory such as the backward color span (children were

asked to recall the colors of disks in reverse order), inhibition such as the fruit stroop task

(children were asked to choose an alternate color than the color they were presented), and

shifting through the dimensional change card sorting task (DCCS; children were asked to sort

cards by one of two dimensions that shifted depending on the trial). They found a significant

relationship between children’s performance on behavioral measures of inhibitory control (i.e.,

whisper task and puzzle task) and EF measures of inhibition (fruit stroop). Additionally, there

were significant correlations between parent report measures of effortful control (i.e., the

effortful control subscale of the ECBQ) and behavioral EF measures of shifting (DCCS). Thus,

this work shows some relations between effortful control and EF with some across methodology

(i.e., behavioral vs. parent report). But not all correlations were significant (e.g., inhibition in

effortful control typically correlated with inhibition in EF). In the same way, Schmidt (2022)

found notable correlations between measures of EF and effortful control. Schmidt (2022)

examined 3-6 year olds through an electronic assessment of EF in combination with parent

reported measures of effortful control through ECBQ. They found a significant correlation

between the inhibition measure on the EF assessment and reports of effortful control from the

parent survey. Further, in their cross sectional study with children (6-8 years) and adolescents

(13-14 years), Kim-Spoon and colleagues (2019) examined performance in several behavioral

EF measures-the digit span task (children were asked to recall a set of numbers in reverse order),

DSSC, the number stroop, the wisconsin card sort task (children sort cards by a rule and must

shift their sorting depending on new rules presented), and the multi-source interference task

(children indicate which number is different from the rest). These behavioral EF measures were

compared to parent report measures of effortful control using the CBQ with subscales of

attention focusing, inhibitory control, low intensity pleasure, and perceptual sensitivity, and they

found correlations between EF and effortful control in both age groups. Specifically, they found

that the subcomponents of inhibition and attention control for both constructs were related thus

supporting the idea that EF and effortful control may overlap.

However, it is also important to note that not all studies found a relationship between

effortful control and EF. For example, Weiss (2023) looked at the potential overlap in first,

second, third, fourth, and fifth grade children through a longitudinal study highlighting items

from the Temperament in Middle Childhood Questionnaire (TMCQ) rated by the child’s teacher

to measure effortful control and the DCCS task to behaviorally measure EF in children between

first and fifth grade and found no evidence that the two constructs share a developmental

pathway. That being said, they state the lack of a clear overlap between these measures could be

a result of the extensive gaps between the collection of data as well as teacher-reported data.

Toddlers

In populations of children under the age of two years, not only are the relationships

between EF and effortful control more inconsistent, but there is a significant lack of research on

this age range altogether. A review of the available literature on relations between the constructs

of executive functioning and effortful control resulted in only five articles that looked at effortful

control and EF within the abstracts when a targeted search (conducted April 20, 2023) included

the keywords ((toddler* OR infan*) AND (“Effortful Control”) AND (“executive function” OR

“cognitive control” OF “executive control”)) was conducted across four databases (Psychinfo,

Scopus, Academic Search Premier, and Pubmed, published in English). Further examination of

the articles revealed that two articles examined effortful control and EF, but did not present data

on the relationship between the two (Tu et al., 2022; Neale et al., 2018). Thus, this area of work

is relatively novel.

Gago Galvagno and colleagues (2019) evaluated 60 infants between 18 and 24 months of

age. The researchers utilized a battery of three EF tasks, the A-not-b task with multiple locations

(children were asked to locate toys hidden in one of five locations after they saw where the toy

was hidden), snack delay (children were asked to wait for a cookie that was placed underneath a

cup until the experimenter rand a bell), and spatial reversal task (children were asked to locate a

toy from under one of two cups but had not observed where the toy was hidden). For effortful

control the ECBQ was used to examine the effortful control subscale. Composite EF was

calculated by the average number of tasks passed while composite effortful control was

calculated by the average across the effortful control subscale. Their results found a positive

correlation between composite measures of EF and composite measures of effortful control

measures, suggesting that infants with higher levels of effortful control were also more

successful when completing EF tasks.

Shinya and colleagues conducted a study in 2022 to understand the development of

executive function in preterm and term infants in Japan. A total of 70 infants participated in the

study at 12 and 18 months of age by completing an eye tracking task (children were placed in

front of a monitor that played a short movie clip followed by two white squares and a reward

stimuli, (i.e., a cartoon character), was presented in one of the squares. The reward stimuli was

presented in the same white square for nine trials before it moved to the opposite side of the

screen and eye tracking technology was used to monitor their attention) at 12 months to measure

EF and their parents completed the ECBQ at 18 months to measure effortful control. Results

showed a correlation between incorrect looking on the eye tracking task at 12 months and

inhibitory control as measured through the ECBQ at 18 months. incorrect or correct looking was

not significantly correlated to the other components measured on the ECBQ (i.e., attention

shifting, low intensity pleasure, cuddliness, attention focusing; Shinya, 2022).

Finally, Johansson and colleagues (2015) conducted a longitudinal study with 66 infants

at 12 to 13 months and again at 24 to 25 months to understand the potential interconnectivity

between EF with behavioral measures including eye tracking in the A-not-B task (children’s eyes

were tracked to examine whether they knew where a hidden character was hidden) and parent

report measures of effortful control (effortful control subscale of the ECBQ). The results

demonstrated a significant correlation between effortful control and executive function at age

two, but found no relation at 1 year. They argue this could be due to the lack of cohesion

between EF and effortful control in infancy when compared to older populations or the rapid

development of self regulatory behaviors during the second year suggesting the two may be more

closely related in older infants such as the 24 month olds.

In sum, prior research has suggested that there may be links between effortful control and

EF, but that it may be based on the age of the population with younger age groups showing fewer

relations as the constructs are rapidly developing and not yet cohesive (Galvagno et al., 2019;

Shinya, 2022; Johansson et al., 2015). Some limitations presented themselves in the available

literature such as the general lack of previous literature on the two constructs within the target

age group (24 months of age and younger), small sample sizes (Galvagno et al., 2019; Shinya,

2022), the lack of diversity in populations (Galvagno et al., 2019), and the lack of reliability in

parent report measures (Johansson et al., 2015; Shinya, 2022).

The Present Study

Through the present study, I examined the possible relationships between effortful

control and EF in study of 14 to 24-month-olds to determine if these constructs overlap as

theoretically proposed (Zhou, 2012) and empirically shown in populations older than 2 years

(Bridgett, 2013). I hypothesized that EF and effortful control will share very little overlap within

this age group (Johansson, 2015) due to developmental frameworks proposing the toddler years

as a formative period during which self-regulation demonstrates dramatic growth (Miller &

Marcovitch, 2015; Rothbart al., 2007).

Methods

Participants

Sixty toddlers aged 14-, 18-, or 24- months (I

age

=19.24, SD=.435) participated in the in-

lab portion of the data collection and 52 of their respective parents/guardians completed a parent

survey following the appointment. Of the parents who responded, 68.8% identified as Caucasian,

7.8% identified as African American, 6.3% identified as Asian, 4.7% identified as Hispanic,

1.6% identified as another race or ethnicity, and 10.8% chose not to respond when asked the

racial demographics of the primary caregiver. For the racial demographics of the secondary

caregiver, guardians reported 64.1% identified as white, 6.3% identified as African American,

4.7% identified as Asian, 1.6% identified as Hawaiian or Pacific Islander, and 23.3% chose not

to respond. For the 82.8% who responded, annual household income ranged from less than

$10,000 to over $140,000, and 71.7% reported an annual income of $60,000 or more.

Procedure

This research was conducted as a two-part study that required children’s in-lab

participation and parents’ report of behavior through an online Qualtrics survey. For the in-lab

portion of the study, children and their parent(s) came into a lab on the University of Mississippi

campus. The children’s parent or guardian completed consent forms and a brief survey about

children’s sleep from the previous night. The experimenter answered any questions and engaged

with the children in a brief warm-up activity before inviting the children to play a series of

games. Depending on the preferences of the children and parents, children were either placed in

a high chair or on the parents' lap to complete the activities. Parents were asked to naturally

redirect the children’s attention to the task in the event that the children engaged with the parent

during a task. Additionally, parents had the option to watch the activities from an adjacent room,

though this was not common. In response to COVID-19, an air purifier was used and researchers

offered to wear face masks and provide facemasks for children, however these were generally

not used and any mask worn by the experimenter was clear to allow children to see facial

expressions and cues. The experimenter then presented the children with a series of 10 tasks in a

fixed order to prevent confounds caused by order effects: (a) multilocation A-not B, (b) imitation

sequence game, (c) delay of gratification task, (d) rule shift game, (e) boxes task, (f) object

retrieval, (g) spatial reversal, (h) imitation sorting task, (i) snack delay task, and (j) theory of

mind task (Miller & Marcovitch, 2015). The fixed order of the tasks alternated between differing

task requirements (e.g., searching, imitating, and waiting) and theorized requirements (e.g.,

working memory, inhibition, and switching). Due to the age group of the selected population,

experimenters maintained a flexible nature with respect to the tasks in the event that one of the

children refused to complete the task (e.g., skipped tasks, revisited tasks, switched hiding

materials). Children were also given breaks as needed. After completing the series of tasks,

parents were asked if they had any questions and were given information about the survey and

gifts for the appointment completion (a $50 gift card and a t-shirt). Email invitations to complete

the survey via Qualtrics were sent out within two days of the initial appointment, and parents

received one reminder email if the survey was not completed. For the purposes of this project, I

only included a subset of data which included 9 of the 10 in-lab behavior measures and the Early

Childhood Behavior Questionnaire (ECBQ) subscales included in the parent survey.

Behavioral Measures of Executive Function

To measure executive function, I utilized a total of 9 tasks that differed in measurement type and

hypothesized task requirements (inhibitory control, working memory, and shifting attention) but

all aligned with the goal of understanding behavior regulation across scenarios. To accommodate

a wide age range and rapid development, all tasks had multiple levels and children progressed to

the next level of a task if they passed an earlier level. A total EF score was calculated by

summing the number of levels passed across all 9 tasks. Figure 1 Provides a depiction of all 9

tasks.

Figure 1.

Depiction of Nine Executive Function Tasks

Delay of Gratification Object Retrieval Snack Delay

(a) Depictions of Inhibition Tasks

Imitation Sequence Imitation Sorting Boxes

(b) Depictions of Working Memory Tasks

A-not-B Rule Shift Spatial Reversal

Inhibitory Control. Children were presented with three tasks thought to measure inhibition, all

of which had two levels. Figure 1a shows a depiction of all the inhibition task materials

Delay of Gratification Task (Kochanska at a., 1998, 2000). During level 1 of the delay

of gratification task, children were taught not to touch an appealing train toy that was placed

within arms reach and were told to instead play with a less appealing caterpillar noise maker.

The train toy was activated for 10 seconds after a delay of 30 seconds and again for twenty

seconds after an additional 30-second delay. If the children inhibited their behavior and did not

touch the train during the entire task, they passed and moved on to level 2. During level 2, a clear

box was presented with a curtain, and the experimenter instructed the children not to peek while

they got a surprise ready. An electronic dog was placed inside where the children could not see

and was activated, making noise continuously for 120 seconds. The children passed the task if

they did not lift the curtain and peek for the entire 120-second increment. Thus scores for this

task ranged from 0 to 2.

Object Retrieval Task (Diamond, 1990; Garon et al., 2014). During the first level of the

object retrieval task, a clear box made of plexiglass was presented with only the back open, and a

pink rattle toy was placed inside. The experimenter asked the children to retrieve the toy; if the

children retrieved the toy in 60 seconds, they moved on to level 2. In level 2, a new clear box

with two clear doors was presented. The pink rattle toy was placed inside using one of the doors,

but that door was then locked and turned to face the child. To pass the task, the children had to

retrieve the toy through the back door within 60 seconds. Thus scores for this task ranged from 0

to 2.

Snack Delay (Kochanska et al., 1996; Bialecka-Pikul et al., 2018). During the snack

delay task, children were instructed not to eat a snack (e.g., Goldfish or Cheerio) that was under

a clear cup until the experimenter told them to; if the children waited 60 seconds, they were

instructed to eat the snack and they moved on to level 2. Level 2 consisted of four trials that

required the children to wait varying lengths of time (10 seconds, 20 seconds, 30 seconds, and 15

seconds) before eating a snack that was under a clear cup when the experimenter rings a bell.

The children passed level 2 if they successfully waited during all four trials.

Working Memory. Children were presented with three tasks thought to measure

working memory. Figure 1b shows a depiction of all the inhibition task materials.

Imitation Sequence Game (Wiebe & Bauer, 2005; Wiebe et al., 2010). The imitation

sequence game had two levels, which required the children to follow sequenced directions.

During level 1, two 3-step sequences were modeled by the experimenter. The children were then

presented with all the materials needed to complete the target sequence, as well as some

materials from the distractor sequence. If the children completed the three steps of the target

sequence in 90 seconds, they moved on to level 2. In level 2, the children were presented with

two 6-step sequences that were both modeled by the experimenter. The children were then

presented with all the materials to complete the target 6-step sequence and some of the materials

from the distractor sequence. If the children completed the six steps of the target sequence within

90 seconds, they were considered to pass level 2.

Imitation Sorting Task (Alp, 1994; Miller and Marcovitch, 2015). The imitation sorting

task required children to mimic the sorting of toys into their respective buckets over three levels.

Level 1 had five trials during which the experimenter sorted one toy into one bucket. If the

children correctly put the toy in the bucket within 20 seconds, they passed the trial. The children

were considered to pass the level if they passed three of the five trials. During level 2, two toys

were sorted into two buckets over three trials. Children were given up to two attempts for each

trial. If the children correctly put each toy into its respective bucket within 20 seconds, they were

considered to pass the trial. If the children passed two of the three trials, they moved on to level

3. Level 3 also had three trials, with two attempts for each trial; however, the children were now

asked to sort three toys into two buckets. They passed the trial if they correctly sorted the three

toys into the two buckets within two attempts. The children were considered to pass level 3 if

they passed two of the three trials.

Boxes Task (Diamond et al., 1997; Wiebe et al., 2010). The boxes task had two levels

and required the children to search boxes and find toys. During level 1, three different color

boxes with different shaped lids were presented to the child, and the children watched as toys

were placed in all boxes. The experimenter then hid the boxes from the child’s view with a white

foam board for five seconds before inviting the children to look for the toys. The first box the

children touched was considered their selection for search. After each search, the experimenter

occluded the child’s view of the boxes for five seconds with a white board before representing

the boxes and encouraging the children to look for a toy. To pass the task, the children must have

found all three toys without making four consecutive errors (searching in a box that had already

been searched). If the children passed level 1, they moved on to level 2, in which six different

color boxes with six different shaped lids were presented. Again, the children watched as the

experimenter placed toys in each of the boxes before the experimenter blocked the child’s view

for five seconds. The children were then encouraged to look for toys in the boxes. If the children

located all six toys without making four consecutive errors (looking in a box that had already

been searched) they passed level 2.

Shifting Attention. The children were also presented with three tasks thought to measure

shifting attention. Figure 1c shows a depiction of all the inhibition task materials.

Multi Location A-not-B Task (Marcovitch & Zelazo 2006; Miller and Marcovitch,

2011, 2015). During the multi location A-not-B task, an apparatus was presented that contained

five hiding locations. In level 1, the children were shown a toy being hidden in one of the five

locations before a foam board was placed in front of the apparatus to obstruct the child’s view

for 10 seconds. The children were then instructed to find the toy. Level 1 contained three trials

during which the toy was placed in the same location each time. The children were considered to

pass the trial if they located the toy before searching incorrectly four consecutive times and they

were considered to pass level 1 if they passed all three trials hidden at the same location. Level 2

contained one trial in which the children had to find the toy at the new location without making

four consecutive errors to pass. During level 3, the experimenter moved the toy to a new location

and introduced the multistep procedure that had to be completed before children searched for the

toy. This procedure required the children to remove two blocks and move a curtain before they

were able to search for the toy. This level contained six trials during which the children had to

find the toy in the same location six times without four consecutive errors to pass. During level

4, the toy was moved to one more new location and children had to follow the multistep

procedure and locate the toy once without four consecutive errors.

Rule Shift Game (Bernier et al., 2010; Carlson et al., 2004; Zelazo & Resnick, 1991;

Zelazo et al., 1995). The rule shift game contained three levels and required the children to sort

small and large animals into their respective bucket. During level 1, children were presented with

one bucket (the “mommy bucket”) and were asked to put “mommy animals” into the bucket.

They were then presented with six “mommy animals” one at a time and asked where they went.

If the children put five of the six animals into the bucket, they passed level 1 and moved on to

level 2. In level 2, the children were given two buckets (the “mommy bucket” and the “baby

bucket”) and told that “mommy animals” go in the “mommy bucket” and “baby animals” go in

the “baby bucket”. The children were then presented with three “mommy animals” and three

“baby animals” in a fixed order and asked to place them in their respective buckets. The children

passed level 2 if they correctly sorted five of the six animals. During level 3, the children were

introduced to a new rule that required them to put “baby animals” into the “mommy bucket” and

“mommy animals” into the “baby bucket”. The children were then presented with twelve animals

in a fixed order and asked to sort them by the new rule. The children passed level 3 if they

correctly sorted ten of the twelve animals correctly.

Spatial Reversal Task (Epsy et al., 1999). The spatial reversal task had three levels and

required the children to correctly locate the toy under one of two buckets. During level 1, the

experimenter showed the children the two buckets before placing a foam board in front of the

buckets and telling the children they were going to hide a toy. The toy was hidden out of sight of

children. The experimenter removed the foam board after approximately 10 seconds and asked

the children to find their toy. The children were considered to pass the task if they found the toy

on two consecutive trials without six incorrect searches. During level 2 the same protocol was

repeated now for a new location. The children were considered to pass level 2 if they found the

toy on four consecutive trials without six incorrect searches. For level 3, the same protocol was

utilized for a new location and the children passed the level if they found the toy in the new

location once without six incorrect searches.

Parent Report Measures of Effortful Control

Subscales from the Early Childhood Behavior Questionnaire (Putnam et al., 2006) were selected

for parents to rate the frequency of their child’s behavior related to effortful control in attentional

focusing (e.g., “When playing alone how often does your child become easily distracted?”),

attentional shifting (e.g., “When you were busy, how often did your child find another activity to

do when asked?”), and inhibitory control (e.g., “When told “no”, how often did your child stop

an activity quickly?”). The effortful control was one of three scales on the 36-question measure

which was answered using a 7-point Linkert scale. Each scale had twelve questions. Higher

scores indicate better control. This scale was originally designed for children between the ages of

18 to 36 months and reliability for these subscales is typically acceptable (.60 < α < .90, see

Putnam et al., 2006).

Results

Descriptive Statistics, Data Reduction and Missing Data

To calculate a composite EF score, I added the highest level passed across all nine tasks

If a child chose not to complete a task, they were assigned a 0 for that respective task (Miller &

Marcovitch, 2015). Missing data was handled in a pairwise deletion fashion. Table 1 presents

descriptive statistics for the behavioral EF tasks and the parent report ECBQ.

Relationship between EF and Effortful Control

To examine the main research question related to the potential relationship between EF

and effortful control, I first conducted bivariate correlations between average ECBQ score and

total number of EF tasks passed. Consistent with my hypothesis, there was not a significant

correlation between parent reports of effortful control and number of EF tasks passed, r(50)=.18,

p=.20, 95% CI [-.06, .47]. I also conducted a Bayseian analysis to examine the evidence for the

alternative and null hypotheses given the data. Bayesian analyses revealed anecdotal evidence

for the null hypothesis BF

=.24.

There were only two significant relationships between overall effortful control and

performance across the nine EF tasks when examined separately (see Table 2). Overall effortful

control was only related to the highest level passed on the spatial reversal task , r(50)=.297,

p=.03 and snack delay task, r(48)= .45, p=.001. All other correlations were not significant.

When I examined the relationship between the number of EF tasks passed across all EF measures, only 12.5% of the 72 possible correlations

were related r (see Table 2). I found no correlation between the three delay tasks. Within the three working memory tasks, the imitation sequence

task was related to the three boxes task r(56)= .41, p=.001 and the three boxes task was related to the imitation sorting task r(56)= .32, p=.013.

Because there were few correlations across EF and within the component measures of EF and in line with previous research for this age range, I

created a global measure of EF related to the number of EF levels passed across all tasks (Miller & Marvocitch, 2015).

Table 1

Descriptive Statistics for Behavioral EF Tasks and Parent Reported Effortful Control

Range

Effortful Control

3-5.92

4.49

Composite EF

1-13

5.3

2.87

A-not-B

0-4

1.1

1.05

Don’t

0-2

.43

.81

Imitation

Sequence

0-1

.13

.34

Rule Shift

0-1

.40

.49

Object Retrieval

0-2

1.5

.62

Spatial Reversal

0-3

1.7

1.21

Imitation Sorting

0-3

1.4

.92

Snack Delay

0-1

.34

.48

Three Boxes

0-2

.74

*Note: EF tasks measurements refer to the highest level passed

Table 2

Correlations Between EF Tasks and Effortful Control

10.

1. Effortful

Control

-.051

.129

.297*

.096

-.063

.449*

.084

.176

-.046

2. A-not-B

-.112

.061

-.028

.146

.319*

.170

.242

.334*

3. Rule Shift

.141

-.274*

-.006

-.038

-.120

.037

-.145

4. Spatial

Reversal

.105

.042

.254

.253

.455**

.175

5. Don’t

-.019

.180

.277*

.275*

.124

6. Object

Retrieval

-.058

-.148

.264*

.040

7. Snack

Delay

.065

.230

.220

8. Imitation

Sequence

.414**

.057

9. Three

Boxes

.323*

10. Imitation

Sorting

Discussion

The present study examined the association between parent reports of effortful control

and EF performance in toddlers ranging from 14 to 24 months of age. Results support prior

research that shows effortful control and EF share few correlations within the second year of life

(e.g., Johansson et al., 2015). This work may suggest that this period of rapid development may

be responsible for the lack of cohesion between EF and effortful control that I saw in this young

sample.

My failure to find a relationship between overall measures of effortful control and EF

supported my hypothesis that there would be little overlap between the two constructs during this

age group. This lack of overlap was not surprising based on the evidence of weak relations

between EF and effortful control prior to preschool years (Johansson, 2015; see also, Schmidt,

2022). However it is important to note that Baysian analyses did not provide strong evidence for

the null, indicating that more research with larger sample sizes could be helpful in better

understanding the relationship between these two constructs.

The lack of significant correlations between effortful control and EF measures could be a

result of several factors. First, it is important to note that effortful control and EF were measured

using different methods as effortful control was measured by parent report and EF was measured

by in-lab behavioral assessments. This could be problematic as parents report the behaviors their

children exhibit at home whereas behavioral measures are conducted in lab settings with optimal

conditions for children’s performance. Each type of measurement also has its limitations, as

some have noted that parent reports may not be an adequate reflection of estimations of

children’s behavior during this young age range (Toplak et al., 2013). Further, due to the optimal

conditions of in-lab behavioral measures, they may fail to generalize to everyday contexts that

children may be accustomed to. While this may explain the lack of connection between effortful

control and EF, prior research suggests the difference in measurement is not the dominant factor

contributing to these results as these methods are typical in studies investigating EF and effortful

control (Galvagno, 2019; Johansson, 2015; Shinya, 2022). Further, research focused on older age

groups with behavioral tasks used to measure EF and parent report data to measure effortful

control have displayed significant correlations between the two (Weiss, 2023; Schmidt, 2022)

highlighting the age-specific nature of the lack of overlap between the constructs.

The lack of evidence supporting the relationships between effortful control and EF align

with the theory that infancy and toddlerhood are distinct age groups wherein development of

self-regulatory measures are rapidly developing thus, little overlap exists between its

subcomponents (Miller & Marcovitch, 2015; Wiebe et al., 2010). EF literature highlights the

development in EF task performance between the ages of 14 and 18 months (Miller and

Marcovitch, 2015), whereas effortful control appears to develop and stabilize after 18 months of

age (Putnam et al., 2006). Due to the small sample size utilized by the current study,

relationships between the different ages were difficult to distinguish, thus future research with

larger sample sizes is needed to further investigate differences based on age.

Though the majority of our results point to a lack of overlap between effortful control and

EF, two significant correlations were found between the parent report measure of effortful

control and individual measures of EF. Both the spatial reversal task and the snack delay task

were both related to the effortful control scale on the ECBQ. The demonstrated relationship

between the snack delay task and the effortful control subscale could be explained due to the task

being a measure of inhibition that directly correlates to a question on the ECBQ (“When asked to

wait for a desirable item, how often does your child wait patiently”; Putnam et al., 2006).

Additionally, when effortful control is measured through in-person tasks as opposed to the parent

report measures such as were used in this study, the snack delay task is a common measure of

effortful control further explaining the correlation between the measures in this study (Yoo et al.,

2021; Neale et al., 2019). The link between the spatial reversal task and the measure of effortful

control, while weaker, may point to an important early-developing link between the two

constructs though more work is needed to investigate this potential relationship.

In sum, evidence suggests that the lack of relationship between effortful control and EF

during this age range may make sense given the lack of development of the two constructs prior

to preschool age (Miller & Marcovitch, 2015; Putnam et al., 2006). While it is important to note

the differences in measurement (i.e., behavior measures and parent reports) that may have

contributed to confounds in data collection, it is also important to note that these varying

methods of measurement may detect slightly different abilities thus enhancing the understanding

of self-regulatory measures such as EF and effortful control. In-lab behaviors allows researchers

to observe behavior under optimal conditions whereas behavior reports allow researchers to

gauge how an individual performs in everyday situations (Toplak et al., 2013), however, future

research should utilize both behavioral and parent-report measures of both EF and effortful

control to more thoroughly understand the role methods of measurement play on the overlapping

nature of the constructs. Additionally, due to the rapidly developing self-regulatory behaviors

during toddlerhood specifically between 14 and 24 months of age (Bridgett et al., 2013; Putnam

et al., 2006), future studies should investigate larger sample sizes and perhaps investigate the

longitudinal developmental pathways between the constructs to better understand how the

independent constructs of EF and effortful control are developing, but also how their relationship

to one another may change across development.

WORKS CITED

Alp, E. (1994). Measuring the size of working memory in very young children: The imitation

sorting task. International Journal of Behavioral Development, 17, 125-141.

Bernier, A., Carlson, S. M., & Whipple, N. (2010). From external regulation to self-regulation:

Early parenting precursors of young children’s executive functioning. Child

Development, 81, 326-339.

Best, J. R., & Miller, P. H. (2010). A developmental perspective on executive function. Child

development, 81(6), 1641–1660. https://doi.org/10.1111/j.1467-8624.2010.01499.x

Bialecka-Pikul, M., Byczewska-Konieczny, K., Kosno, M., Bialek, A., & Stepien-Nycz, M.

(2018). Waiting for a treat. Studying behaviors related to self-regulation in 18- and 24-

month-olds. Infant and Behavior Development, 50, 12-21.

Blair, C. & Razza, R. P. (2007). Relating effortful control, executive function, and false belief

understanding to emerging math and literacy ability in kindergarten. Child Development,

78, 647-663.doi: 10.1111/j.1467-8624.2007.01019.x

Bridgett, D. J., Burt, N. M., Edwards, E. S., & Deater-Deckard, K. (2015) Intergenerational

transmission of self-regulation: A multidisciplinary review and integrative conceptual

framework. Psychological Bulletin, 141, 602-654. doi: 10.1037/a0038662

Bridgett, D. J., Oddi, K. B., Laake, L. M., Murdock, K. W., & Bachmann, M. N. (2013).

Integrating and differentiating aspects of self-regulation: Effortful control, executive

function, and links to negative affectivity. Emotion, 13, 47-63. doi: 10.1037/a0029536

Carlson, S. M. (2005). Developmentally sensitive measures of executive functioning in

preschool children. Developmental Neuropsychology, 28, 595-616. doi:

10.1207/s15326942dn2802_3

Carlson, S. M., Mandell, D. J., & Williams, L. (2004). Executive function and theory of mind:

Stability and prediction from ages 2 to 3. Developmental Psychology, 40, 1105-1122. doi:

10.1037/0012-1649.40.6.1105

Diamond, A. (1990). Developmental time course in human infants and infant monkeys, and the

neural bases of inhibitory control in reaching. Annals of the New York Academy of

Sciences, 608, 637-676.

Diamond, A. (2006). The early development of executive functions. In E. Bialystock & F. I. M.

Craik (Eds.), Lifespan cognition: Mechanisms of change (pp. 70–95). New York: Oxford

University Press.

Diamond, A., Prevor, M. B., Callender, G., & Druin, D. P. (1997) Prefrontal cortex cognitive

deficits in children treated early and continuously for PKU. Monographs of the Society

for Research in Child Development, 62, 1-206.

Espy, K. A., Kaufmann, P. M., McDiarmid, M. D., & Glisky, M. L, (1999). Executive

functioning in preschool children: Performance on A-not-B and other delayed response

format tasks. Brain and Cognition, 41, 178- 199.

Gago Galvagno, L. G., De Grandis, M. C., Clerici, G. D., Mustaca, A. E., Miller, S. E., & Elgier,

A. M. (2019). Regulation during the second year: Executive function and emotion

regulation links to joint attention, temperament, and social vulnerability in a latin

american sample. Frontiers in Psychology, 10, 1473-1473.

https://doi.org/10.3389/fpsyg.2019.01473

Garon, N., Bryson, S. E., & Smith, I. M. (2008). Executive function in preschoolers: A review

using an integrative framework. Psychological Bulletin, 134, 31-60. doi: 10.1037/0033-

2909.134.1.31

Garon, N., Smith, I. M., & Bryson, S. E. (2014). A novel executive function battery for

preschoolers: Sensitivity to age differences. Child Neuropsychology, 20, 713-736.

doi:10.1080/09297049.2013.857650

Hughes C., & Ensor, R. (2005). Executive function and theory of mind in 2 year olds: A family

affair? Developmental Neuropsychology, 28, 645-668.

Hughes, C., & Ensor, R. (2007). Executive function and theory of mind: Predictive Relations

from Ages 2 to 4. Developmental Psychology, 43, 1447-1459.

Hsing-Fen Tu, Lindskog, M., & Gredebäck, G. (2022). Attentional Control Is a Stable Construct

in Infancy but Not Steadily Linked With Self-Regulatory Functions in Toddlerhood.

Developmental Psychology, 58(7), 1221–1236. https://doi-

org.umiss.idm.oclc.org/10.1037/dev0001362

Isquith, P. K., Gioia, G. A., & Espy, K. A. (2004). Executive Function in Preschool Children:

Examination Through Everyday Behavior. Developmental Neuropsychology, 26(1), 403–

422. https://doi-org.umiss.idm.oclc.org/10.1207/s15326942dn2601_3

Johansson, M., Marciszko, C., Gredebäch, G., Nyström, P., & Bohlin, G. (2015). Sustained

attention in infancy s a longitudinal predictor of self-regulatory functions. Infant

Behavior & Development, 41, 1-11. doi: 10.1015/j.infbeh.2015.07.001

Kälin, S., & Roebers, C. M. (2021). Self-regulation in preschool children: Factor structure of

different measures of effortful control and executive functions. Journal of Cognition and

Development, 22(1), 48-67. https://doi.org/10.1080/15248372.2020.1862120

Kim-Spoon, J., Deater-Deckard, K., Calkins, S. D., King-Casas, B., & Bell, M. A. (2019).

Commonality between executive functioning and effortful control related to adjustment.

Journal of Applied Developmental Psychology, 60, 47-55.

https://doi.org/10.1016/j.appdev.2018.10.004

Kochanska, G., Coy, K.C. and Murray, K.T. (2001), The Development of Self-Regulation in the

First Four Years of Life. Child Development, 72: 1091-1111. https://doi-

org.umiss.idm.oclc.org/10.1111/1467-8624.00336

Kochanska, G., Murray, K., & Harlan, E. T. (2000). Effortful control in early childhood:

Continuity and change, antecedents, and implications for social development.

Developmental Psychology, 36, 220-232. doi: 10.1037//0012-1649.36.2.220

Kochanska, G., Murray, K., Jacques, T., Koenig, A., & Vandeceest, K. (1996). Inhibitory control

in young children and its role in emerging internalization. Child Development, 67, 490-

507.

Kochanska, G., Tjebkes, T. L., & Forman, D. R. (1998). Children’s emerging regulation of

conduct: Restraint, compliance, and internalization fron infancy to the second year. Child

Development, 69, 1378-1389. d0i: 10.2307/1132272

Liew, J. (2011). Effortful control, executive functions, and education: Bringing self-regulatory

and social-emotional competencies to the table. Child Development Perspectives, 9, 1-7.

doi: 10.1111/j.1750-8606.2011.00196.x

Marcovitch, S., & Zelazo, P. D. (2006). The influence of number of A trials on 2-year-olds’

behavior in two A-not-B-type search tasks: A test of the hierarchical competing systems

model. Journal of Cognition and Development, 7, 477-501.

Miller, S. E., & Marcovitch, S. (2011). Toddlers benefit from labeling on an executive function

search task. Journal of Experimental Child Psychology, 108, 580-592. doi:

10.1016/j.jecp.2010.10.008

Miller, S. E., & Marcovitch. S. (2015). Examining executive function in the second year of life:

Coherence, stability, and relations to joint attention. Developmental Psychology, 51, 101-

114. doi: 10.1037/a0038359

Miyake, A., & Friedman, N. P. (2012). The nature and organization of individual differences in

executive functions: Four general conclusions. Current directions in psychological

science, 21, 8-14. doi: 10.1177/0963721411429458

Miyake, A., Friedman, N., Emerson, M., Witzki, A., Howerter, A., & Wager, T. D. (2000). The

unity and diversity of executive functions and their contributions to complex “frontal

lobe” tasks: A latent variable analysis. Cognitive Psychology, 41, 49–100.

Neale, D., Basilio, M., & Whitebread, D. (2018). The Grasping Task: A 12‐month predictor of

24‐month delay task performance and BRIEF‐P inhibition scores. Infant & Child

Development, 27(4), 1. https://doi-org.umiss.idm.oclc.org/10.1002/icd.2092

Neale, D., & Whitebread, D. (2019). Maternal scaffolding during play with 12- to 24-month-old

infants: stability over time and relations with emerging effortful control. Metacognition

and Learning, 14(3), 265-289. https://doi.org/10.1007/s11409-019-09196-6

Nigg, J.T. (2017), Annual Research Review: On the relations among self-regulation, self-control,

executive functioning, effortful control, cognitive control, impulsivity, risk-taking, and

inhibition for developmental psychopathology. J Child Psychol Psychiatr, 58: 361-383.

https://doi-org.umiss.idm.oclc.org/10.1111/jcpp.12675

Posner, M. I., Rothbart, M. K., Sheese, B. E., & Voelker, P. (2012). Control networks and

neuromodulators of early development. Developmental Psychology, 48, 827-835. doi:

10.1037/a0025530

Putnam, S. P., Gartstein, M. A., & Rothbart, M. K. (2006). Measurement of fine-grained aspects

of toddler temperament: The early childhood behavior questionnaire. Infant Behavior and

Development, 29(3), 386-401.

Rothbart, M. K. (1981). Measure of temperament in infancy. Child Development, 52(2), 569-

578. doi: 10.1016/j.infbeh.2006.01.004

Rothbart, M. K., Sheese, B. E., & Posner, M. I. (2007). Effortful control: Linking temperament,

brain networks, and genes. Child Development Perspectives, 1, 2-7. doi: 10.1111/j.1750-

8606.2007.00002.x

Schmidt, H., Daseking, M., Gawrilow, C., Karbach, J., & Kerner auch Koerner, J. (2022).

Self-regulation in Preschool: Are Executive Function and Effortful Control Overlapping

Constructs? Developmental Science, 25, e13272. https://doi-

org.umiss.idm.oclc.org/10.1111/desc.13272

Shiner, R. L., Buss, K. A., McClowry, S. G., Putnam, S. P., Saudino, K. J., & Zentner, M.

(2012). What is temperament now? Assessing progress in temperament research on the

twenty-fith anniversary of Goldsmith et al. (1987). Child Development Perspectives, 6,

436-444. doi: 10.1111/j.1750-8606.2012.00254.x

Shinya, Y., Kawai, M., Niwa, F., Kanakogi, Y., Imafuku, M., & Myowa, M. (2022). Cognitive

flexibility in 12-month-old preterm and term infants is associated with neurobehavioural

development in 18-month-olds. Scientific reports, 12(1), 3.

https://doi.org/10.1038/s41598-021-04194-8

Shonkoff, J. P. & Phillips, D. A. (Eds.) (2000). From Neurons to Neighborhoods. (p. 19-32).

National Academy Press, Washington, DC.

Thomas, A., & Chess, S. (1977). Temperament and development. Brunner/Mazel.

Toplak, M. E., West, R. F., & Stanovich, K. E. (2013). Practitioner review: Do performance-

based measures and ratings of executive function assess the same construct? The Journal

of Child Psychology and Psychiatry, 54, 131 – 143. doi: 10.1111/jcpp.12001

Weiss, E. M. (2023). Self-regulation in elementary school: Do teacher-reported effortful control

and directly assessed executive function codevelop? Developmental Psychology.

https://doi-org.umiss.idm.oclc.org/10.1037/dev0001658

Wiebe, S. A., & Bauer, P. J. (2005). Interference from additional props in an elicited imitation

task: When in sight, firmly in mind. Journal of Cognition and Development, 6, 325-363.

Wiebe, S. A., Espy, K. A., & Charak, D. (2008). Using confirmatory factor analysis to

understand executive control in preschool children: I. latent structure, Developmental

psychology, 44, 575-587. doi: 10.1037/0012-1649.44.2.575

Wiebe, S. A., Lukowski, A. F., & Bauer, P. J. (2010). Sequence imitation and reaching measures

of executive control: A longitudinal examination in the second year of life.

Developmental Neuropsychology, 35, 522-538. doi: 10.1037/0012-1649.44.2.575

Wiebe, S. A., Sheffield, T., Nelson, J. M., Clark, C. A. C., Chevalier, N. & Espy, K. A. (2011).

The structure of executive function in 3-year-olds. Journal of Experimental Psychology,

108, 436-452. doi: 10.1016/j.jecp.2010.08.008

Yoo, H. N., & Smetana, J. G. (2022). Associations among child temperament, parenting, and

young children's moral and conventional understanding: The moderating role of self‐

regulation. Social Development (Oxford, England), 31(3), 619-638.

https://doi.org/10.1111/sode.12571

Zelazo, P. D. (2004). The development of conscious control in childhood. Trends in Cognitive

Science, 8, 12-17. doi:10.1016/j.tics.2003.11.001

Zelazo, P. D. (2015). Executive function: Reflection, iterative reprocessing, complexity, and the

developing brain. Developmental Review, 38, 55-68. doi: 10.1016/j.dr.2015.07.001

Zelazo, P., Müller, U., Frye, D., & Marcovitch, S. (2003). The development of executive

function in early childhood. Monographs of the Society for Research in Child

Development, 68, 1-137. doi: 10.1111/j.0037-976x.2003.00260.x

Zelazo, P. D., & Reznick, J. S. (1991). Age-related asynchrony of knowledge and action. Child

Development, 62, 771-735.

Zelazo, P. D., Reznick, J. S., & Pinon, D. E. (1995). Response control and the execution of

verbal rules. Developmental Psychology, 31, 508-517.

Zhou, Q., Chen, S. H., & Main, A. (2012). Commonalities and differences in the research on

children’s effortful control and executive function: A call for an integrated model of self-

regulation. Child Development Perspectives, 6, 112-121. doi: 10.1111/j.1750-

8606.2011.00176.x