Executive functions organize thoughts toward purposeful behaviors (1). Defects in these functions can indicate damage to the prefrontal cortex. Early assessment can detect defects in this area in the early stages and consider rehabilitation programs for children (7). A wide variety of tests have long been available to evaluate executive functions. Among those that assess executive functions in children, it can be found the Fish Flanker Task, Dots Task (Hearts & Flowers), and the Form Span Task, designed by Adele Diamond.

These three tests examine the three basic components of executive functions: inhibitory control, cognitive flexibility, and working memory. Considering the usefulness of these tests, the importance and necessity of studying executive functions in children, and the lack of valid and special tools for preschool children to directly measure executive functions in the country, known tests in this area need to be translated and standardized. Therefore, this study was conducted with the aim of a preliminary study of three questions: 1- validity, 2- differential power, and 3- reliability of the mentioned tests to provide a tool for measuring executive functions in preschool children.

Methods

Seventy-four children aged 4 to 6 years in Tehran were evaluated in this study. After obtaining parental consent, they completed the Behavior Rating Inventory of Executive Function Preschool version (BRIEF-P), the Child Behavior Checklist Preschool version (CBCL-P), and the demographic information form. After collecting and scoring the questionnaires, based on the scores of subscales of DSM of CBCL, the subjects were divided into normal and clinical groups. Then, Flanker task, Hearts & Flowers task and Form Span were taken from children in two sessions of 10-15 minutes. The data were analyzed using a correlation test to evaluate the simultaneous criterion validity. Then, to measure the differentiation power of the test, the mean scores of the normative and clinical groups were compared using the independent t-test. The tests were repeated five weeks apart for half of the subjects to check their reliability. Data were analyzed by Excel 2016 and SPSS-22.

Results 

Spearman correlation was calculated between the results of the BRIEF questionnaire and the results of the Diamond tests to evaluate the validity of the tests. The correlation rate in the working memory component of the two tests was 0.63, the inhibitory control component was 0.87, and the flexibility component was 0.89.

Accordingly, a significant relationship was found between the components of executive function tests and BRIEF subscales.

In the next step, to evaluate the differentiation power of the tests, the scores of the subjects in the clinical group (n=15) were compared with 15 subjects in the normal group using the independent t-test. 

The findings of Table 1 show that there is a significant difference in all components between the scores of normal and clinical groups (P<0.01). These differences indicate the optimal diagnostic validity of executive function tests.

1. Results of independent t-tests to compare normal and clinical children for executive function components

Normal

Clinical

Tasks

Mean

Standard Deviation

Mean

Standard Deviation

T Score

Working memory

51.02

9.60

43.65

9.24

2.67

Inhibitory control

52.36

7.83

43.41

7.62

3.97

Cognitive flexibility

52.45

7.49

42.29

7.73

4.46

Five weeks after the initial test, a retest was performed for half of the subjects to evaluate the reliability of the test. The correlation rate was 0.71 in the working memory component of the test and retest, 0.80 in the inhibitory control component, and 0.78 in the flexibility component. Accordingly, there is a good correlation between the scores of the components of executive function tests in the test and retest. Therefore, these tests have the desired reliability.

Conclusion

The presence of these tasks in preschool age is essential for early detection of defects in the prefrontal cortex. Seemingly, due to the use of color shapes and game format, the child communicates better with the tasks and provides more realistic results of the child's ability than the interview and paper-pencil tests. Another advantage of these tasks is that they are specific to the task area. In many questionnaires, the terms used to score several abilities are common or overlapping. However, in these tasks, according to the possibility of calculating the score in each part of the task, the score of selective attention, shifting, inhibition, and flexibility can be obtained separately. Furthermore, since the reaction time is recorded in computer tests, scores can be calculated and compared separately regarding accuracy and speed. This feature allows therapists to design appropriate interventions and exercises according to the subject's needs. These tests can be used in various cases, such as measuring and diagnosing executive function disorders in clinical groups, such as attention deficit/hyperactivity disorder, coping disorder, anxiety disorders, and depressive disorders. These tests also can be used for designing children's interviews.

In a similar study in Canada on 42 children aged 3-5 years, there was a strong correlation between the components of inhibitory control, working memory, and flexibility in a set of tests designed to measure executive function and BRIEF questionnaire scores. These findings confirm the results of the present study. One of the limitations of this study is the impossibility of sampling in other cities and larger samples.

All participants participated in the study with their consent and their parents' consent. The children were free to leave the room whenever they did not want to continue the assessment or felt tired. Individuals' information is protected. In performing the test, the examiner behaved in such a way that the child did not feel defeated or weak, and participating in this study did not cause any psychological or physical harm.

Samineh S. Pourtakdoust, Javad Hatami & Alireza Moradi: Designed and conceived the presented idea. Samineh S. Pourtakdoust: performed experiments and analyzed data. Samineh S. Pourtakdoust: Performed testing section during the experiment. All authors supervised the research & provided critical feedback, and reviewed the initial and final versions.

This research received no financial support from any funding agency in the public, commercial, or not-for-profit sectors.

The authors thank all the participants, colleagues, and experts who helped us conduct this study.

The authors acknowledged no potential conflicts of interest regarding this article's research, authorship, and/or publication.