Hot Executive Function Assessment Instruments in Preschool Children: A Systematic Review

The study aimed to systematically analyze the empirical evidence that is available concerning batteries, tests or instruments that assess hot executive functions (EFs) in preschoolers, identifying which are the most used instruments, as well as the most evaluated hot EFs. For the review and selection of articles, the systematic review methodology PRISMA was used. The article search considered the EBSCO, Web of Science (WoS), SciELO and PubMed databases, with the keywords “Hot executive function”, “Assessment”, “test”, “evaluation”, using the Boolean operators AND and OR indistinctly, between 2000 and April 2021. Twenty-four articles were selected and analyzed. The most commonly used instruments to assess hot EFs in preschool children were the Delayed Gratification Task, the Child’s Play Task, and the Delayed Reward Task. Amongst those analyzed, 17 instruments were found to assess hot EFs in preschoolers. The accuracy and conceptual clarity between the assessment of cognitive and emotional components in EFs is still debatable. Nevertheless, the consideration of affective temperature and reward stimulus type, could be an important influence when assessing EFs in this age range. Evidence of the possible involvement of cortical and subcortical structures, as well as the limbic system, in preschool executive functioning assessment has also been incorporated.


Introduction
This study is framed in the context of neuropsychology, a clinical discipline pertaining to a part of neuroscience that focuses on a neural interpretation of the behavioral and affective cognitive evidence in people [1,2]. Along these lines, the mnesic, attentional, and executive functions (EFs), which is the particular interest of this study, are evaluated according to a person's response in relation to a possible neurological correlate.
Executive function (EF) is a concept incorporated within the discipline of neuropsychology [3,4]. Alexander Luria associated the prefrontal lobe with the control of superior intellectual activity, whereas the term Executive Functions (EFs) was attributed to Muriel Lezak [5]. EFs are defined as a set of neurocognitive skills that can inhibit, regulate and/or plan behavior, emotional behavior, and complex social functioning, contributing to adaptability, and orienting goal-directed behavior in the individual. Through these processes, proactive, autonomous, and productive activities can be developed [2,[5][6][7][8][9].
In recent decades there has been significant interest in the evaluation of EFs during childhood since they contribute to school and social development, and their dysfunction being the cause of some psychopathological and behavioral disorders [2,[10][11][12]. Therefore, preschool is considered a period of greater sensitivity in executive development [13], linked to the maturation of cortical brain regions [14,15].
EFs can be classified into cold (only cognitive components) and hot (with socioemotional components). The former requires logical and critical analysis, involving conscious control of thoughts and actions, such as planning and cognitive flexibility, where preferentially the dorsolateral prefrontal cortex is involved [16]. On the other hand, hot EFs

Materials and Methods
The article review was based on international PRISMA statements [32]. The article selection process began with the identification of articles in the Web of Science (WoS), EB-SCO, SciELO and PubMed databases, using the keywords in Spanish and English "Función ejecutiva cálida", "Evaluación", "Prueba"; "Hot executive function", "Assessment", "test", "evaluation", with the Boolean operators AND and OR as appropriate, between the periods 2000 to 2020 in April 2021. The review process was confirmed by a second reviewer to ensure the inclusion validity. Differences in opinion were discussed, reaching consensus on the inclusion or exclusion of the study. The methodological quality of the reviewers for each review, as well as the evidence, was assessed using PRISMA.
The review of articles is based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) considering selected articles that refer to the effect of interventions on the topic of warm EFs [33,34].
A total of 118 articles were found in WoS, 54 in EBSCO, 16 in SciELO, and 4 in PubMed, for a total of 192 results. The inclusion criteria consisted of (i) strictly empirical research, (ii) a primary focus on Hot EF assessment instruments, (iii) studies done only with a preschool age range, and (iv) publications occurring between 2000 and 2020. The exclusion criteria pertain to (i) systematic reviews or meta-analyses, (ii) articles presenting data only on Cold Executive Functions, and (iii) articles not including a preschool aged sample.
Of the 192 results, 59 duplicates were eliminated among the four databases, leaving 133 articles. Thereafter, 109 articles were discarded for being systematic reviews (n = 13), meta-analyses (n = 3), for not including instruments that evaluate hot EFs (n = 38) and for not including a preschool aged sample (n = 55) (See Figure 1).
were discussed, reaching consensus on the inclusion or exclusion of the study. The methodological quality of the reviewers for each review, as well as the evidence, was assessed using PRISMA.
The review of articles is based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) considering selected articles that refer to the effect of interventions on the topic of warm EFs [33,34].
A total of 118 articles were found in WoS, 54 in EBSCO, 16 in SciELO, and 4 in PubMed, for a total of 192 results. The inclusion criteria consisted of i) strictly empirical research, ii) a primary focus on Hot EF assessment instruments, iii) studies done only with a preschool age range, and iv) publications occurring between 2000 and 2020. The exclusion criteria pertain to i) systematic reviews or meta-analyses, ii) articles presenting data only on Cold Executive Functions, and iii) articles not including a preschool aged sample.
Of the 192 results, 59 duplicates were eliminated among the four databases, leaving 133 articles. Thereafter, 109 articles were discarded for being systematic reviews (n = 13), meta-analyses (n = 3), for not including instruments that evaluate hot EFs (n = 38) and for not including a preschool aged sample (n = 55) (See Figure 1).

Results
Between the years 2000 and April 2021, there exist 24 articles related to the topic of hot EFs in preschoolers, mainly focused from 2011 to 2020 (n = 22; 91.7%), where 87.5% (n
Research seems to be predominantly done in the USA (n = 7; 29.2%), then Canada (n = 3; 12.5%), and Italy, the Netherlands, and Poland combined (n = 2; 8.3%). Some variables have been associated with altered hot EFs in preschool children, such as preterm birth (n = 2; 8.3%), obesity (n = 1; 4.2%), attention deficit disorder (n = 1; 4.2%), and developmental coordination disorder (n = 1; 4.2%). Among the most used instruments with hot EFs in preschool children are the Delay of Gratification Task (n = 9; 37.8%), followed by Children's Gambling Task (n = 6; 25%), and Gift Delay Task (n = 6; 25%), totaling 17 instruments. The most studied hot EFs were Gratification Delay (n = 16; 66.7%), Decision Making (n = 7; 29.2%) and Emotional Self-Regulation (n = 4; 16.7). The list of instruments that were considered, together with the function evaluated and psychometric aspects that account for reliability and validity aspects, are shown in Table 1. It can be seen that some studies refer exclusively to hot EF aspects and others to the combination of cold and hot EFs.  The hot EF assessment instruments reviewed, for the most part, have an individual format. Two relevant classifications were identified: the first being related to decision making by means of a card game (IGT and ChGT), and the second being related to a gratification delay while waiting to be rewarded (LMT, DGT, GDT, SDT, PSRA, MIDA, CDT, and SwT). Assessment instruments typically use rewards in their application, among them, those which incorporate food (LMT, DGT, DCCS, SDT, PSRA, and CDT), stickers (SS, DGT), coins (DGT), gifts (GDT), and toys (PSRA), were distinguished. The aim of this article is to systematically analyze the empirical evidence available on the types of batteries, tests, or instruments that assess hot EFs in preschool children. In summary, 17 evaluative tools published in 24 articles were reported (See Table 2).
As can be observed in Table 2, the DGT test and PSRA battery stand out as being the most frequently used instruments with measuring gratification delay since they involve considering or waiting for a greater reward. Others, such as CDT and SDT, wait for the sound of a bell to receive a reward. Whereas, with computational applications, games that include prizes, versus waiting for gratification, have also been used. An example of such being MIDA which is more commonly used in children over 5 years of age. Gestures made when approaching a more entertaining toy are also measured using tests such as SwT. Questionnaires that are completed by external observers, such as teachers or parents, where they check the access gratification control to EFIn, are also used. Others deal with attentional inhibition to a desirable object while performing tasks, which can be seen in tests such as DCCS and GDT. ERC and the EM-FIST Tests evaluate affective flexibility in the performance of a task with the influence of a significant character. There are also those in which rewards are given when the least advantageous one is chosen, such as the LMT and the SS, a situation that is referred to as inverse reward in the case of the former. The IGT and ChGT use cards where people evaluate those that have something advantageous such as smiley faces.  [81]). Two rewards are presented, a small one (2 pieces) and a large one (10 pieces), the child being evaluated must wait to obtain the larger reward. Adapted from Kochanska et al., (1996 [71], 2000 [72]). The activity consists of instructing the child to try not to touch the gift for a delay of 1 min.

Discussion
The revised articles evaluate hot and cold EFs, covering emotional and cognitive aspects respectively, noting distinct definitions concerning hot and cold EFs with a slight difference between them [82]. For some authors, EFs are a set of neurocognitive abilities that allow adaptability and generate goal-directed behaviors, including emotional and cognitive aspects [5][6][7][8][9]. Yet, according to other authors, this concept only considers cold FEs [83]. Despite these conceptual differences, there is consensus that both aspects are involved in the integral development in individuals [84].
The most studied hot executive function would be gratification delay, which is defined by the willingness to access immediate rewards in favor of delayed gratifications of higher value [85]. Regarding the underlying neural mechanisms, as described in literature, limbic areas of the brain are associated as being sensitive to immediate rewards, while the lateral prefrontal cortex is considered as influencing the ability to delay gratification [86,87]. This neurocognitive assessment process involves two paradigms in a young child's inclination to exhibit a gratification delay: delayed gratification choice and maintenance [46].
The second most studied hot executive function is decision making, despite being often classified as a cold or cognitive EF exclusively, is also involves emotional or hot components actively influencing this function [4]. Possible positive and negative outcomes or consequences, associated with a specific choice of activity, are considered in decision making [88]. This process is related to the somatic marker hypothesis, since actions are analyzed and organized by virtue of future outcomes, with positive or negative valence [24]. As described by Kable and Glimcher (2009), the performance of this task involves dorsolateral prefrontal areas for decision making, the amygdala to express emotional unpleasantness, basal ganglia to modulate behavior, the anterior cingulate cortex in order to relate amongst one another, and the nucleus accumbens in reward circuits, among others [89], where the IOWA Gambling Task (IGT) has been mostly used [69].
The third most studied hot executive function is self-regulation, in which evidence shows that the ventromedial and orbitofrontal cortex are associated as playing an active role in the processes of inhibition, emotion and reward elicitation [88]. Self-regulation is a complex and multifactorial concept [90] that acts at different executive functioning levels that represents the ability to voluntarily plan and modulate one's behavior for an adaptive purpose [91]. Some authors consider the concept of behavioral self-regulation as synonymous with hot EFs [92,93], while others extend the concept, considering it as both hot and cold at the same time [94]. The Preschool Self-Regulation Assessment (PSRA) is used to evaluate hot and cold aspects where the focus is on the EF of delayed gratification [56][57][58][59].
Reward is a common factor in hot EF assessments although there is disagreement as to whether a hot EF task must include rewards, or some type of appetitive stimulus [95], or whether it only needs to elicit an emotional stimulus or increased motivation for it to be performed [16]. In relation to this, some authors propose that the EF performance depends on the influence that the motivational factor has on being either intrinsic or extrinsic [96].
According to reviewed evidence, hot EFs have implications on ADHD symptoms and behavioral problems [21]. They can be affected in adverse contexts, although improving when a training system is incorporated [47]. Hot EFs were not associated with the development of physical or relational aggression, nor significantly with Theory of Mind (ToM), socioeconomic adversity, cognitive self-regulation, or obesity [42,43,48,56]. There are no reported studies relating hot EFs and autism spectrum disorder (ASD) in preschoolers, though both concepts should be further studied. Such is due to the implication that this neurocognitive function has in personal and emotional interpretation, regulation of social behavior and understanding of social and contextual cues [97], all aspects that may be altered in ASD as currently conceptualized [98].
Favoring hot EFs, especially in the willingness to delay gratification, decision making and behavioral self-regulation, during early childhood predicts greater success academically and socially [99,100] and is to health and economic well-being in adulthood [101][102][103][104].
Hot EFs begin to develop early in life, enabling the development of inhibitory control, attention and working memory, forming the basis of voluntary control of behavior and thought, and the ability to interpret one's own emotion as well as another's, therefore enhancing the capacity for self-regulation and learning [5].
Consequently, longitudinal studies that consider problems such as addictions, behavioral disorders, or other pathologies where hot EF based brain structures are involved, are suggested so that predictive hot EF characteristics in preschoolers can be identified. It is also recommended that more studies and instrumental validations be carried out in both Latin American and Spanish-speaking countries, since there is little evidence of research in this population. The future of EF assessment faces the challenge of explaining the integration of cognitive and emotional components. Therefore, the evaluation of EFs should consider the type of stimulus or reward involved and must take into account the temperature of the cognitive activity.
Two limitations can be observed in the study, one being that these instruments are based on visual stimuli, thus requiring a preserved visual capacity, while not considering other sensory-perceptual pathways such as auditory, somesthetic, chemical, olfactory or gustatory. On the other hand, only four electronic databases were selected for the searches: EBSCO, WoS, SciELO and PubMed. Thus, it is possible that there are other articles available on the subject. In addition, the lack of conceptual unification of EFs limits the number of articles identified on the evaluation of hot EFs at a preschool age.

Conclusions
The most commonly used hot EF instruments in preschoolers are the Delay of Gratification Task (DGT), Gift Delay Task, Children's Gambling Task and Preschool Self-Regulation Assessment (PSRA). Most of them assess delayed gratification, affective decision making and self-regulation with emotional components. The accuracy and conceptual clarity between the assessment of cognitive and emotional components in EFs is still debatable. The consideration of the affective temperature and the decision to choose the reward stimulus may have an impact on EF performance, situations that are suggested as involving limbic system structures, the lateral prefrontal cortex, ventromedial cortex, and the nucleus accumbens, among others. Likewise, the study of EFs integrated in their hot and cold aspects, can report a panorama of greater comprehensiveness in the cognitive-affective functioning of preschool children. However, the instruments are not designed with inclusivity criteria that considers other sensory-perceptual channels that may influence EFs. It is pertinent to continue studies in order to incorporate instruments from diverse information inputs into the executive system. The promising development of hot EFs in preschoolers can contribute to a diagnosis and design of rehabilitation strategies, allowing them to better perform in their educational and socio-cognitive life.
Author Contributions: V.M. and L.M. were responsible for the conceptualization, investigation, formal analysis and writing the original draft preparation. S.C. was responsible for the systematic review methodology. K.C. was responsible for reviewing and editing. H.B. was responsible for the supervision and editing of the entire review. All authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.