Executive Functions in Non-WEIRD Populations: Reflections from Ecuador and Thailand

1.1. Executive Functions and Human History

Earlier in this text, we have described studies linking child labor, homelessness, and poverty to enhanced executive function, suggesting a strong influence of culture on the development of these functions. Such associations are likely of interest to anthropology and related disciplines that study how culture interacts with human development. Despite this, the contribution of anthropology to understanding cognitive functions has remained relatively limited until recently [25]. However, there is a resurgence of interest in the cultural and social contributions to cognitive phenomena. A recent and influential review focused on neuropsychiatry concluded that nearly all cognition is social in some way, and further, nearly all psychiatric illnesses are based on social cognition [26]. Metacognition was seen as crucial to understanding these concepts within a classical executive function framework (i.e., the supervisory system of Norman and Shallice [3]).

Similarly, paleoanthropology was once focused on language use as the core human skill, allowing advanced cultural development. Language was seen as the factor distinguishing modern humans from their ancestors [27]. However, recently, there has been interest in how the development of cognitive-control skills in archaic humans, specifically executive working memory ability, may have contributed to their survival and to their relatively recent grand achievements, including the development of complex societies, technology, etc [28]. This is because executive control allows for technical achievements through insight, planning, and innovation. Hence, it has recently been argued that ‘executive functions lay the neural and cognitive foundation for civilization and culture’ [29].

The historical origin of executive control in humans is controversial; however, it is clear that some change in cognition has occurred. Some scholars have suggested that a genetic change in the human genome occurred around 100,000 years ago, leading to greater development of the prefrontal cortex [30]. As that area is the part most closely associated with executive function [1, 5, 6, 13], the change may have provided a biological substrate for increased behavioral flexibility. In addition, enhanced working memory, a key aspect of executive function, may have allowed ancient humans to make greater use of complex skills learnt and stored in long-term memory, providing for more flexible technical cognition [28]. An alternative explanation is that the social nature of human existence, spanning from hundreds of thousands of years ago to modern times, has driven the need for a flexible cognitive system that provides reflection, allowing for complex interactive behaviors, such as reciprocal altruism, imitation, self-regulation, social manipulation, and defenses against that manipulation [31]. In the context of the self-regulatory model, the need for social flexibility has led to the evolution of executive cognitive control and the necessary expansion of the prefrontal cortex in humans. This neurocognitive base has allowed for the development of cultural standards, artefacts, tools, and, within recent millennia, writing systems that can sustain advanced cultures [29].

Furthermore, cultural interactions influence executive functions bidirectionally. Evidence from studies on diverse cultures is in support of this. Ethnographic studies with Mayan children in Mexico suggested that the way they apply top-down cognitive control is influenced by their greater autonomy and domestic responsibilities, in contrast to Westernized Mexican children [32]. Evidence from both Slovakia and Vanuatu suggested that following rituals promotes delayed gratification in children, an aspect of inhibitory executive control [33].

1.2. Cross-cultural Influences on Executive Function

From a biological perspective, race does not exist [34]. Therefore, the variation in executive functions observed in different parts of the world is mainly due to cultural variations. A striking example of this comes from brain imaging of cognitive functions. The Go/No-go task measures a core executive function, response inhibition, which is closely linked to activity in the frontal lobes of the brain, as are other core executive functions [13]. When Japanese adults, USA citizens of European descent, and USA citizens of Japanese descent perform this task, their activation within the frontal lobe varies, and the level of activation is associated with their cultural beliefs. Most importantly, activation levels varied between Japanese citizens and the citizens who lived in the USA. But there was no difference in inhibition-induced frontal lobe activation between USA and Japanese Americans [35]. This strongly suggests that the culture people live in is the driving force behind cross-national differences in cognitive processing, and not ‘race’.

It has been proposed that executive functions develop from the exertion of reaching goals and meeting the demands within specific living environments through a contextually bound set of knowledge, beliefs, and norms [36]. Thus, given the apparent malleability of executive functions to cultural factors, cross-cultural studies could likely be fruitful methods of identifying the parameters of human executive control. Nevertheless, there is a dearth of studies comparing executive task performance across societies or different sectors of society. Research focused on variation in countries often compares perceived racial groups, a pattern common in USA-based research. For example, historically, it was reported that there exist gaps in cognitive performance of Black and Hispanic populations performing worse than White and Asian students, and gaps between immigrants and nonimmigrants, and native and also non-native speakers [37]. Indeed, the background of people and the living context determine how cognitive abilities develop, but ‘race’ per se is unlikely to be an essential factor.

Returning to studies that correctly focus on culture, one important and replicated observation is that children in some East Asian countries appear to develop executive control at younger ages than children in Western countries. For example, Ellefson et al. [38] showed adults in the U.K. and Hong Kong to perform at equivalent levels on various tests of executive function and develop with age in the same way. However, adolescents in Hong Kong outperformed adolescents in the UK. This suggests that cultural variables affect how quickly executive functions develop from infancy to adolescence, but not the peak of performance in adulthood. Other effects of culture on executive function development in children and adolescents suggest that in most cultures, but not all, girls develop executive function ability faster than boys and that bilingual children develop executive control more readily than monolinguals [39].

Although Ellefson et al. [38] found no evidence for adult differences in executive function ability in their East-West comparisons, a study that compared adults raised in the USA and adults raised in India did detect differences in executive task performance across cultures. Kelkar et al. [40] found that India-born participants outperformed USA-born participants on some executive function measures, but the reverse pattern was shown on other measures. These East-West comparisons are helpful; however, it should be noted that they make a very broad comparison and also represent only two broad regions. Comparisons between other cultures regarding cognitive function are relatively scarce. One region that is very much left out of these comparisons is Latin America. Although some progress is being made, Gago‐Galvagno et al. [41] have recently described several idiosyncrasies associated with the development of executive functions in Latin America related to local cultural values, educational systems, income inequality, etc.

Following on, income inequality between countries is likely a substantial factor driving cross-cultural gaps in cognitive test performance. Executive functions have been identified as cognitive skills of particular interest in understanding and aiding national socioeconomic development [42]. Nevertheless, there are likely other factors that may cause differences in executive skills between cultures. One might be how tests are designed. It is well-known that most commercially sold cognitive assessments (e.g., intelligence test batteries) are mainly developed for application within WEIRD cultures. The criticism suggests that this is problematic because of the lack of an adequate representation of a diverse population in the development of cognitive tests. Consequently, there may be a major problem with how culture-fair the tests are. We can take as an example the Pyramids and Palm Trees Test, which is widely used to assess semantic knowledge. When this was applied in Thailand, 25 of the 52 line-drawing stimuli (48%) were found to be inappropriate, because they portrayed scenes that, although easily recognizable to people in the UK (where the test was developed), were not easily recognizable by Thai people, such as an image of a lord mayor in ceremonial regalia [43]. Similarly, when a battery of different executive function tests from WEIRD countries was applied to indigenous children in Mexico, only 6 (35%) of the children responded, as expected [32].

Nevertheless, Obradović and Willoughby have argued that, across cultures, the fundamentals of executive function are similar, including aspects, such as their criterion validity, biological bases, and relationships with demographic and family predictors [42]. Furthermore, they have provided a 3-step guide to developing executive function assessments for non-WEIRD cultures, starting with a review by local experts to identify possible problems and solutions, using translators from the community, and finally, performing iterative pilot testing to identify and correct any problems.

One reason the fundamentals of executive functions are likely equivalent across cultures, provided the assessment method is appropriate, is the substantial overlap among the processes involved in task performance. Scores on cognitive assessments of executive function are often highly related to the scores on tests of fluid intelligence [44, 45]. This is important for the current analysis as the set of processes underlying fluid intelligence may be the same cognitive processes employed in performing many tests of executive function. This set of procedures is known within cognitive neuroscience as the multiple-demand system [45]. The fact that a core brain network may underlie variation in executive/fluid intelligence is based on the observation that scores on all cognitive tests positively correlate with each other, a phenomenon known as the positive manifold, forming the basis of the concept of general intelligence [46]. The positive manifold has been demonstrated in many cultures, WEIRD and non-WEIRD, suggesting that the core basis of executive functions may be invariant across human cultures [47]. Most relevant to the current analysis, it has been demonstrated in Ecuador as well [48]. A study from Brazil also highlighted these issues. By applying the principles of cognitive measurement proposed by the British psychologist Charles Spearman in 1904 [46], 120 years later, the Brazilian researchers were able to develop a test that performed as expected, yielding a valid measure of general intelligence and the expected relationships with demographic variables [49].

Although the presence of the positive manifold of cognitive test scores appears to be invariant across human cultures and is even seen in a range of non-human animals [50], the stimulus materials used in cognitive tests, particularly executive function assessments, can be a problem. For example, the Delis-Kaplan Executive Function System [51] was the battery of tests that Kelkar et al. [40] used to compare USA- and India-raised adults in their cross-cultural study. However, it is a commercial test specifically developed for the USA market and optimized to be in a format suitable for people in the USA. The India-raised participants were tested in English to allow direct comparison with the English-speaking USA-raised participants. This raises the problem that direct comparisons of task performance may never be genuinely culture-fair because the task formats and methods may be more comprehensible within one culture than the other.

The language issue is important as many tests of executive function use words or other linguistic features as stimuli. As an example, the Hayling Test [9] requires participants to complete sentences with either appropriate or inappropriate words, depending on the condition, such as ‘he posted the letter without a …..’. In English, the language in which the test was originally developed, it is common for objects to appear at the end of a sentence; however, in other linguistic cultures, atypical grammatical structures may be required, or may not be possible at all, making valid test application difficult. Even if the stimulus materials are non-linguistic, there are inevitably task instructions, and, with executive function tests, often quite complex rules to follow. Thus, language can, in some cases, buffer adaptation, making it straightforward, and, in others, pose a risk to validity. For this reason, where possible, it is recommended to choose tasks that minimize language content [42] when planning to adapt assessments to countries different from where they were originally developed. Some scholars have argued that the linguistic content of cognitive tests tends to favor some ethnic groups over others [37], challenging their validity as measures of ability. On the other hand, at the psychometric level, it has been shown that the basic factor structure of cognitive tests across linguistic cultures is invariant [47], suggesting that cross-cultural application may often be appropriate. However, it should also be noted that linguistic differences may be important. Translating task instructions or stimulus materials from English to Korean, Japanese, or Chinese, for example, can be challenging because of the differences in written forms. In contrast, in countries that use a Latin-script adaptation, adaptation may be more straightforward. Similarly, adaption between languages with similar origins, such as the Romance languages spoken in Italy, Spain, Portugal, etc., may be less challenging and allow greater validity. Furthermore, language-free assessments are not necessarily free of bias. Classical work in cognitive anthropology has shown that even pictorial stimuli, such as drawings, can be interpreted very differently by people from different cultures [52].

An example of this, and a laudable attempt to address the WEIRD bias in executive function assessment, was a recent ethnographic study with Mayan youth living in Mexico [32]. The Mayans are indigenous to the Americas and have a culture that substantially differs from the Westernized European-heritage majority population. Gaskins and Alcalá [32] found that several aspects of executive function testing, using tasks developed in WEIRD nations, were alien and unmotivating to the Mayan youth, partially explaining their ostensibly relatively low performance. They suggested several ways in which tasks could be developed to be relevant within the culture and hence be more valid measures of actual top-down executive cognitive control.

The point is that various factors influence how test takers can apply and perform cognitive tasks, which vary by culture, separately from true executive processing capacity differences. In this study, we used a qualitative and reflective approach to consider this in more detail by comparing issues encountered by psychologists working in two quite different non-WEIRD cultures, Ecuador (in South America) and Thailand (in Southeast Asia). The researchers working in these countries contributed their experiences to compare and contrast culture-specific issues in the measurement of executive functions. To achieve this, they provided an analysis of the cultural context of each country, linking it to cognitive and assessment issues. Working together, they suggested actions to ameliorate some of the identified problems.

2.1. Ecuador, Nation and Culture

Ecuador, situated in the northwestern region of South America and intersected by the equatorial line, is a nation of stark contrasts and profound diversity. Historically, colonization by Spain, beginning in the 16th century, has had a huge impact on the country. This took power from the existing states governed by native Amerindian groups, particularly the Inca empire. Although the country has long had independence and statehood, the impact of European culture is ubiquitous. As in most of Latin America, descendants of the European colonizers wield substantially more political and economic power than people within indigenous populations [62]. Another important aspect of Spanish colonization was the introduction of Catholicism, which remains the dominant religion in Ecuador and has had a broad and profound impact on cultural values within the country [63]. This influence cannot be understated and likely drives many aspects of the personality and political attitudes of the Mestizo ethnic majority [64].

The population of Ecuador is over 16 million people, inhabiting its Andean peaks (‘La Sierra’), Amazonian rainforests (‘El Oriente’), coastal plains (‘La Costa’), and insular wonders of the Galapagos Islands [65], and each area has a distinct climate, economy, topography, culture, and demographic characteristics. There are approximately 13 million self-identifying Mestizo inhabitants, and 1.3 million people identify as indigenous, divided into about 19 ethnic groups. In addition, around eight hundred thousand citizens identify as Afro-Ecuadorian, about 1.3 million identify as Montubios (natives of the coastal region), and over three hundred thousand individuals identify as White or other ethnicities. According to the last national poll, there are more than 200,000 immigrants from different countries. Beyond ethnic diversity, there are 14 indigenous languages spoken across diverse regions [66].

It is well known that the living context largely determines the physical and socio-emotional characteristics of a human being [67]. Of course, this is not different for cognitive development. The prevailing socioeconomic conditions in Ecuador are marked by widespread issues, including unemployment, racism, and discrimination [68], which link to the cultural and historical influences on cognitive and emotional development [69]. In addition, the current challenges in Ecuador include malnutrition and ill health, limited education [70], healthcare access disparities [71], proneness to natural disasters, political instability, corruption, endemic violence, crime, and narco-trafficking. The issue of child labor is generally a consequence of economic conditions that favor work over schooling. The location of Ecuador close to the international illegal drugs trade is also important in this respect because many out-of-school children become employed informally in this illicit industry, both in manufacturing and selling [72]. As Ecuador borders Colombia, the long-running conflict in that country has impacted the mental health of many people, particularly at the border regions.

People experiencing poverty in Ecuador constitute a quarter of the population, being income-based, and one in twelve people live in extreme poverty. In the urban areas, the poverty rate is 18% and that of extreme poverty is 4%, whereas in the rural areas, the poverty percentage is 41%, and that of extreme poverty is 17%. Beyond all these socioeconomic issues, Ecuadorian cultural diversity is marked by family- and community-oriented people living in a country with a vast natural richness and several ecosystems that allow the population access to productive lands, affordable organic food, and beautiful landscapes. On the one hand, this represents a positive aspect of Ecuador's potential, impacting the development trajectories of its inhabitants. On the other hand, it also presents significant challenges in providing equitable education, assessment, and diagnostic practices that accommodate language diversity while addressing the cognitive needs of students from such diverse contexts [73].

2.2. Issues in Assessing Executive Functions in Ecuador

At present, there are multiple challenges to assessing executive function in both academic research and applied settings (e.g., educational and clinical). In many cases, these potentially invalidate the findings or promote injustice. One of the most prominent intelligence tests applied in Ecuador is the Wechsler Intelligence Scale for Children [74], based on a hierarchical structure of cognitive processes where the g factor (also known as general intelligence) is a consequence of the positive manifold of correlations among lower-level processes [46, 48, 50]. Contrary to this, Kovacs and Conway [75] argue that there are domain-general processes that correlate more with domain-specific processes than the domain-specific processes with each other. From this perspective, it would be desirable to avoid using non-specific subtests and instead prioritize cognitive evaluations whose processes are more targeted on cognitive constructs, such as working memory or attentional control.

Although many executive cognitive assessments are employed in Ecuador, their use tends to be limited by linguistic and cultural factors. Linguistic problems arise because participants or patients in cognitive research studies need to be assessed in their usual languages. Assessments widely used in the English-speaking world to measure executive function, such as the Hayling Test and the Cognitive Estimates Test, rely on orally delivered stimulus material. Therefore, translation into a local language is needed. In most cases, this problem can be addressed, as Spanish is the main language in Ecuador, and therefore, some tests can be obtained from studies in larger or more developed Latin American countries or in Spain. They can then be adapted to address cultural differences between the originator country and Ecuador. Indeed, this has been done for both the Hayling Test [9] and the Cognitive Estimates Test [76].

However, a substantial proportion of the Ecuadorian population, including many people from the indigenous American populations, does not understand Spanish well. In that case, very few options exist to measure executive function. The Rowland Universal Dementia Assessment Scale is a clinical tool that includes aspects of executive functioning and has been designed to minimize cultural and linguistic effects. This has the potential for use in some indigenous populations in Ecuador and has been shown to function well with indigenous Quechua speakers in neighboring Peru [77]. This is encouraging as Kichwa, a Quechua variation, is the most widely spoken indigenous language in Ecuador.

Nevertheless, language-based executive function assessment options for Ecuadorians who speak indigenous languages remain extremely limited. In this respect, bilingualism among indigenous populations in Ecuador is another element worth considering in terms of executive function assessment. There is an existing controversy concerning whether bilinguals outperform monolinguals in executive tasks. For example, in a study that included 11,000 adults and another that included 4,500 children, there was no difference in executive tasks between monolinguals and bilinguals [78, 79]. In another study, bilingual participants actually performed worse than monolinguals [80]. On the other hand, a study that included 18,000 children showed that those from bilingual homes outperformed those from monolingual homes [81]. Accordingly, Bialystok and Craik [82] argue that bilingualism has a positive lifespan effect on developmental trajectories, academic success, and delayed symptoms of dementia. The aforementioned results suggest that other factors could influence these outcomes, rather than just a simplistic monolingual vs. bilingual dichotomy, as the varied sociolinguistics and cultural elements that revolve around language influence its use. Indeed, research on the cognitive science of language has become more insightful as it takes on a sociolinguistic perspective [83]. From a practical perspective, it may be sufficient for the assessors to apply their expertise in the interpretation of cognitive test scores within the context of multilingual test takers. Though this does require quite high levels of training in clinical or educational cognitive assessment, which many psychologists working in Ecuador lack access to.

Fortunately, many common executive function assessments are language-free, as they use rather abstract stimulus materials. The most obvious example is the Wisconsin Card Sort Test [84]. However, the use of those tests has not been explicitly validated for Ecuadorian culture. Furthermore, most executive function tests, such as the Wisconsin Card Sorting Test, and most standardized cognitive tests in general, have been developed within WEIRD English-speaking cultures. There is an often-implicit assumption within such cultures that monolingualism is the norm, and multilingualism is a rare exception. Tests are thus designed from that perspective. However, the monolingualism observed mainly in WEIRD English-speaking cultures is the exception, with multilingualism being the norm in non-WEIRD cultures [85]. The bilingualism or multilingualism of many within the Indigenous American populations of Ecuador, therefore, may influence their cognitive performance in ways that differ from the cognitive constructs assessed in the original WEIRD version.

A further limiting factor is that modern cognitive assessment is rapidly moving towards more ecologically valid methods. For example, the Hotel Test [86] uses a typical British workplace scenario to study time management, attention shifts, etc., which are essential components of executive functioning. But as tests become more realistic, as developed in WEIRD countries, more problems emerge in the application in other non-WEIRD contexts. The Hotel Test was used in a research study in Ecuador [87], where the procedures of working in a hotel were somewhat different, and several aspects of the procedure had to be altered, raising issues of construct validity. As another example, the Jansari assessment of Executive Functions, validated in the UK, uses office role-play and is presented in a virtual reality environment [88]. This assessment has been used in some student research studies in Ecuador [89], again with questions about whether ecological validity can apply across cultures.

With respect to the applied issue, the problem of access to valid executive function assessments is more critical. The stakes are high in clinical and educational work involving cognitive assessment of executive functions. A misdiagnosis of impairment or educational potential difficulties can have substantial real-life implications. Related to this, there is a lack of methods for deciding on performance abnormality. In applied work in WEIRD countries, this is usually achieved by using normative tables to estimate how far an individual client’s performance falls from the average. Such normative tables are costly and complex to compile and only remain valid for perhaps a decade. Due to these practical constraints, few normative tables are available for cognitive tests in Ecuador. One exception, which avoided the costs of full norming, was that adjustments for IQ scores on the WAIS-IV for the Ecuadorian population have been provided that can be applied to the original normative tables developed in Spain [90]. The same data set has been used to additionally assess test validity [48]. This approach can circumvent some of the difficulties with test norming in non-WEIRD countries, such as Ecuador, in certain situations.

However, if full normative tables are to be developed for use in Ecuador, following internationally-recognized guidelines, cross-sector collaboration is essential, likely involving commercial, governmental, and NGO support. The practical aspects of collecting sufficiently diverse data, i.e., normative tables of executive function test batteries, cannot be achieved by small groups of academics working alone. This level of collaboration could, however, support fair assessment standards.

3.1. Thailand, Nation and Culture

Thailand is a middle-income country located in Southeast Asia. Unlike Ecuador, where colonialism has formed much of the modern culture, Thailand has never been colonized by another country [95]. This fact has substantial relevance to the national self-image, outlook, and structure of Thai society. Although many languages are spoken in the country, Central Thai is the dominant language, and most citizens speak it as either a first or second language. It is written in a script that is specific to the country.

Thai culture is considered a rather hierarchically structured society, with significant differences between rich and poor, making it the country with the highest income inequality in the East Asia and Pacific region. This inequality is reflected in differences in human development and leads to disparities in education and occupational levels. A study by Topothai et al. [96] revealed that cognitive development was the least attained domain among the four capability domains. The prevalence of appropriate cognitive development was found to be positively correlated with family wealth, as it was associated with better cognitive outcomes. Also, Thailand is ruled by a democratic government; however, the importance of the royal family within Thai culture and governance is substantial.

In terms of cultural values, similar to Ecuador, Thailand places significant importance on collectivism, prioritizing in-group goals, interdependence, and strong ties with extended family. However, Thailand more likely endorses traditional gender roles and less likely assertiveness and competition compared to Ecuador, which places a greater emphasis on status orientation.

The culture of Thailand, historically, has been greatly influenced by Buddhism, which is the dominant religion in the country. This has had, and continues to be, a significant influence on behavior and outlook, influencing many aspects of the day-to-day psychology of Thai people [97]. The culture is also substantially influenced by ancient Chinese culture, particularly Confucianism. This cultural influence cannot be understated, as Confucianist education concepts are interwoven into the Thai approach to learning and teaching. In Thailand, as in other regional nations, this influences academic study, beliefs in how one achieves, and how people should be held responsible for achievements or failures, anxiety, and self-doubt [98]. A strong cultural influence of Confucianism is present in Thailand and its neighboring countries too, and has likely played a substantial role in the overall regional identity, cooperation, and economic development of Southeast Asian nations [99].

Furthermore, while Thailand is predominantly religiously and ethnically homogenous, Muslims constitute the largest minority group, comprising approximately 6% of the population [100]. Islam dominates in the three southernmost provinces bordering Malaysia (i.e., Narathiwat, Yala, and Pattani). The Muslim majority, primarily ethnic Malays, also includes children of immigrants from South Asia, China, Cambodia, and Indonesia, as well as ethnic Thais. Due to the ongoing conflict in the southernmost region, children in this particular area are at risk of developmental delays and growth failure [101]. Negative impacts on child development are also sexual exploitation and trafficking in the region, which is also associated with the substantial narcotics industry [102].

There are approximately 20 distinct communities, known as ‘hill tribes’ (chao khao), comprising approximately 1 million individuals residing in the mountainous northern and western regions of the country. Each tribe may have a unique language and customs, typically within about five main linguistic families. These populations commonly engage in subsistence farming or swidden agriculture. More importantly, hill tribe communities remain among the poorest in Thailand, with low schooling rates, exacerbated by inadequate schools and a lack of instruction in their native language.

Currently, shortages in various occupational fields in Thailand are reflected in deficits in cognitive skills, such as mathematical reasoning, writing, and reading comprehension, as well as in social skills, such as service orientation, and technical skills, such as programming and technology design. The most lacking knowledge areas are computers and electronics, clerical knowledge, and customer and personal service. With Thailand facing global trends, such as population aging, globalization, and automation, high-level cognitive and social skills shortages are expected to worsen, similar to trends observed in many countries.

Unlike Ecuador, the typical pattern of high levels of epilepsy in low- and middle-income countries is not observed [103]; however, some other disorders with neuropsychological implications are substantially more prevalent, in particular HIV [104].

3.2. Issues in Assessing Executive Functions in Thailand

The increasing demand for clinical neuropsychological assessments, including executive function assessment, has led to the development of several tools for assessing cognition within the Thai population. However, until recently, there have been very few instruments available. Various approaches to the development and use of cognitive assessment tools are evident. The main approach has been to adopt tools developed in other national contexts, primarily in WEIRD countries. Some of these instruments have been used by simply translating administration instructions and materials and relying on the original normative data for interpretation. Others have been modified to improve linguistic and cultural relevance, sometimes with new normative data being collected [105]. In addition, a small number of indigenous instruments have been developed from the ground up to maximize linguistic and cultural relevance (such as the Color Trails Test). Nevertheless, there remains a continuing need for more extensive and up-to-date normative data, particularly for executive function assessments designed for the population of children and adolescents. At present, the development of such tools is often limited by numerous factors, including the limited local expertise available within the country.

Concerning the coverage of the main domains of cognition, the primary purpose of most tests has been found to detect dementia, most typically Alzheimer’s disease or mild cognitive impairment. The emphasis has, therefore, been clinical. The domains of orientation, delayed recall, attention, language, and perceptual motor function are relatively well covered. In contrast, executive functions are generally much less covered. However, recent criticism of the lack of coverage of executive functions in the standard dementia screening tests has led to slightly better coverage in some of the more recently developed tests, such as the Montreal Cognitive Assessment, which has recently been validated for clinical use in Thailand [106]. However, even when tests of executive functions are included in these screening tests, they are often not comprehensive.

Some intensive and established neuropsychological tests are applied in Thailand, such as the Delis-Kaplan Executive Function System [51], which has been used, for example, to detect impairments associated with HIV+ status [107]. Nevertheless, there are no Thai-generated norms for this battery that appropriately account for age, education level, and other Thai-specific issues. Researchers have often simply translated the test instruments from the original language into Thai to adapt test materials for executive function assessment procedures in Thailand. This approach, however, fails to address potential differences in understanding the materials, task rules, and other elements that might be culturally relevant. In these cases, the materials are maintained with the original meaning, with only minimal modifications, such as changing a few words in a word list or pictures. Then, these tests are validated by comparing the test performance between clinical groups and healthy controls. Almost all of the tests used or adapted in Thailand have been developed for people over the age of 50 and primarily focused on detecting dementia. Examples are the Mini-Mental State Examination [108] and the Chula Mental Test [109]. These test instruments, therefore, are not suitable for use in younger groups, such as children, adolescents, and those in early or middle adulthood. A notable concern is the lack of executive function tests that have been adapted or validated for the many ethnic minority groups living in Thailand. As a result, options for valid assessment of executive functions within these groups are very limited. In some cases, tests validated in other countries may offer potential usefulness, such as a dementia screening tool that includes executive function items developed for use in Myanmar [110] may be useful within the diaspora of that country residing in Thailand.

The high prevalence of HIV in Thailand [104] has also driven developments in cognitive testing, due to the striking negative impact of AIDS on executive functioning [107]. This has provided impetus to the development and adaptation of tests of executive function to the Thai context [91], as well as for the development of normative performance tables for clinical neuropsychological use of several executive function assessments [111].

Nevertheless, there remains a need for more normative data for educational and clinical assessments. Only two cognitive screening tests account for age, education, or both when generating standard scores that can be used clinically to determine whether performance is impaired. The first is Addenbrooke’s Cognitive Screening Test Thai Version, which generates a standardized score referencing age and education [112]. The second is the Thai Montreal Cognitive Assessment [106], which has two cut points based on the level of education to differentiate healthy people from people with cognitive impairment. In summary, the validity and practical applicability of executive function testing adapted in Thailand can be questioned.

From an educational perspective, although research suggests that teachers value executive function as a personal strength among students [113], and some basic research in Thailand highlights the importance of working memory in achievement [94], research in this applied field in Thailand remains minimal. This is partly due to the dearth of tests specifically developed or validated for basic research on children and adolescents in the country. The idiosyncrasies of Thai culture and its language make adopting tests and experimental materials from other cultures for psychoeducational use fraught with problems. Consequently, the use of executive tools in basic cognitive research and in assessing cognitive impairment among Thai individuals is currently challenging. There are several limitations, including the limited number of executive function tests available in Thailand, the methods of test adaptation being difficult, and normative tables being inconsistent with the Thai cultural context. As a result, providing the knowledge of test adaptation to Thai clinicians and researchers is urgent. Additionally, provision of training in cognitive assessment to a professional level is rare in Thailand, as much of clinical and educational psychology focuses on well-being. Addressing issues related to executive function could benefit from greater recognition of the importance of cognitive testing and its integration into postgraduate training courses.

5.1. A Framework for Bespoke Executive Function Assessment Development

We suggest several steps that could be used to develop culturally-appropriate assessments of executive function. People familiar with both the concept of executive cognition and the local culture must be involved at every step. This refers to psychologists, neuroscientists, or other relevant experts who are of the same culture or have at least performed relevant ethnographic studies. The first step should be to identify basic aspects of possible tasks that would be compatible with the experiences, existing skills, and interests of the target population. Points to consider here are the medium (e.g., spoken, pencil and paper, computerized, or gamified approaches), use of feedback and tolerance of stress, and relatability of the task contents. Secondly, the researchers should research, in detail, the fundamental aspects of executive functioning, such as goal-directedness, attention-demanding, top-down control, limited resources, non-routineness, etc [1, 3-6]. The researchers should be focused at this point on what executive control is, in terms of definition, rather than on schemes, classifications, taxonomies of different executive functions, etc., as these may be overly biased by WEIRD interpretations and psychometric observations. In the third stage, the researcher must produce a basic task that requires executive control and harmonizes with the previous stages. This is the stage that requires innovation. However, novel cognitive test design is already commonplace in fields, such as experimental psychology, and also clinical [124] and cognitive [125] neuropsychology, and the same principles can be applied here. Important practical considerations include producing an assessment that yields a range of scores without ceiling or floor effects, with the range determined by the efficiency of executive control. An additional consideration at this stage is test reliability. These steps, if followed closely, may produce a culturally-appropriate assessment with face validity as a measure of executive function. The next stage requires piloting on diverse participants, but including those from the target population. A final, optional stage could be to assess more formally the validity of the assessment, for example, demonstrating that achievement measures on the task are negatively associated with psychiatric or neurological illness.