Applying the neuroscience of language to the training of early childhood educators

Executive Summary

• Science-oriented curriculum development and training of early childhood educators only emerged in the late 20^th Century, prompted by data from experimental psychology, which revealed the amazing capacities of young children.
• Today, early childhood educators are expected not only to care for young children but also to promote the integral development of their cognitive, emotional, and social abilities.
• Neuroscience can be a powerful tool to prepare early childhood educators to rise to this challenge.
• Because language is crucial for academic achievement, the neuroscience of language can provide a basic framework to understand how the brain works and learns.
• Neuroscience can also guide the development of tools for early detection of difficulties and to support remedial initiatives.
• Regular updating of early childhood educators’ training is needed due to rapid advances in neuroscience.

Introduction

Pre-school was initially conceived as a place without specific curricula where young children were cared for while their parents worked. Curricula and science-oriented training of early childhood educators only emerged by the late 20^th Century, promoted by the findings of experimental psychology, which revealed the amazing capacities of young children.

Today, early childhood educators are expected not only to care for young children’s wellbeing and physical safety but also to promote the integral development of their cognitive, emotional, and social domains from birth until they start attending school. We believe that theoretical and applied neuroscience can significantly contribute to preparing early educators to succeed in these challenging tasks.

The research in some developing countries describes gaps in the disciplinary training of early childhood educators, mainly because they are well trained in social skills but less consistently in cognitive ones. Indeed, early childhood educators have facilities to establish successful affective interactions with infants and young children, which impact positively on the social and emotional development of the children. However, they do not use these positive contexts to train the cognitive skills of children that influence academic achievement, such as critical thinking, metacognition, reading, and math¹.

The neuroscience of language

A classic example of the contributions of neuroscience to a better understanding of early childhood development is language acquisition, which starts in the womb and extends beyond puberty. The initial stages of such learning take place in the first year and then amplify as a cascade. Indeed, healthy infants begin with a set of speech sounds that they use to discover and build words and then discover the rules with which to combine these words in their native language. Notably, these gains in verbal communication are accompanied by rapid brain growth, and a remarkable sensitivity to external stimuli.

The crucial role of native phoneme learning

Today, infants are perceived as human beings able to select, process, and interpret information from the environment in which they develop from birth. That initial rudimentary knowledge relates to later linguistic and communicative achievements at school. As in a cascade, the progress or delay in developing such abilities during early development shape the subsequent development of related skills.

One of the most studied examples of this developmental continuity is the learning of the native phoneme repertoire. There are roughly 7,000 languages spoken in the world today. Among them, linguists have recognized hundreds of vowels and consonants, also known as phonemes. Phonemes correspond to the set of sounds that minimally differ between words in a particular language. For instance, in English the phrases, “there was brass” and “there was grass”, differ in the slight and subtle difference between the phonemes /g/ and /b/. Interestingly, no language uses all known phonemes, but only a restricted repertoire of them, i.e., those that distinguish between words in that language.

By the 1980s, behavioural studies showed that new-born children distinguish phonemes through non-nutritive sucking, demonstrating an increase in sucking pressure as they hear new phonemes.²

Neuroscientific research has added to our understanding of early language acquisition by measuring the healthy neonate brain activity associated with phoneme change detection. Thus, neuroscience has provided a mechanistic explanation of this important stage of learning, both in typically and atypically developing children. The most common techniques used in infant brain studies are electroencephalography, which records the electrical activity of the brain, and near-infrared spectroscopy, which records changes in the oxygenation levels of the brain, at the scalp. Both techniques can measure the infant’s detection of subtle but crucial distinctions between phonemes.

Electroencephalography

Near-infrared spectroscopy

Both methods can safely be used in babies born at full term³ or pre-term (i.e., as early as ~27 weeks of gestational age)⁴. Thus, neuroscience allows us to map the brain areas involved in the phoneme distinction task. The results show that, across languages, speech activates similar areas in neonate and adult brains. In this way, brain data on the initial stages of extra-uterine life can illustrate the mechanisms underpinning how we process phonemes.

The intensity of the electrical brain response when distinguishing phonemes is reduced in neonates from families with a history of dyslexia⁵. In 7-month-old infants, the smaller the response during phoneme distinction the smaller is the child’s vocabulary at 24 months of age⁶. Electroencephalogram techniques are probably the cheapest and safest way to explore brain activity in developmental neuroscience. This has been successfully used in some developed countries such as Finland to monitor phoneme detection in neonates from families with a history of dyslexia⁵, and in pre-schoolers with language difficulties.

Performance in distinguishing phonemes also depends on other factors, which develop simultaneously with speech processing in young children. One of these is the quality of oral-motor movements. A recent study of 3-month-old infants showed that they need to move the tongue to distinguish certain phonemes. In English, distinguishing /d/ from /t/ requires that the tongue moves from the border of the teeth to behind the teeth. Thus, the brain response while distinguishing between /d/ from /t/ is reduced when infants use a teething toy that hinders tongue movements⁷. This study suggests that providing young children with periods of free tongue movement may improve phoneme perception and thus early language learning.

As mentioned above, no language uses all of the hundreds of possible phonemes, but just a reduced set of them. It is currently accepted that by the sixth month, infants can distinguish native from non-native vowels⁸, and by the twelfth month native consonants from non-native ones⁹. Other studies indicate that this ability depends on the degree of exposure to speech and on brain maturation^10,11,12. Indeed, infants become more sensitive to the specific phonemes they are exposed to¹⁰. Moreover, by comparing how healthy full-term and pre-term infants learn the native repertoire of consonants we have shown that brain maturation constrains the learning of the native phoneme repertoire^11,12. Thus, healthy pre-term infants who were born three months before full maturation and received whole speech from birth do not experience accelerated learning of the repertoire of native consonants. Thus, restriction could be because learning the native phoneme repertoire requires a certain level of neural maturation. Interestingly, although pre-term infants do not experience accelerated learning of the native repertoire of phonemes, they are more advanced than full-term infants in vocalizing face-to-face interactions¹³ and following the gaze of others¹⁴, suggesting that social cognition is sensitive to external stimulation even when the brain is very immature. Thus, social skills are crucial for communication, even when language is not yet available.

Another factor that contributes to learning of the native phoneme repertoire is social interaction. A study found that 9-month-old infants learn better from direct interaction with a person than when they watch a video of the same person¹⁵. Personal interaction is more attractive, challenging, and rewarding for young humans than interaction through screens. Thus, the learning of the native phoneme repertoire is an active process that depends on brain maturation and systematic speech stimulation.

Phoneme difficulties as predictors of future development

Detecting language and communication delay at early stages of childhood developments is highly relevant to education, primarily because language and communication delay are powerful predictors of reading difficulty at school age, which in turn is a strong predictor of academic failure, poorer work opportunities and social development, and lower quality of life¹⁶.

A recent UNESCO report cites the alarming statistic that 617 million children and adolescents worldwide currently do not achieve the minimum performance level in reading (UNESCO, Statistics, 2017), despite most attending school. Depending on the language, between eleven and thirty percent of these cases may be explained by biological factors, such as dyslexia (2–20%)¹⁷, hearing loss due to recurrent otitis media, which affects approx. 9% of preschoolers^18,19, or by non-identified factors that are presumed to be biological, such as chronic stress.

Dyslexia has been the subject of intensive neuroscientific research. One of the more frequent difficulties reported is the problem of distinguishing between phonemes⁵. Thus, 70–90% of the reading failure reported by UNESCO is environmental in origin, mostly associated with lack of access to high-quality education.

A preventive approach involves developing efficient systems that allow early detection of the approx. 30% of biologically determined cases and structured early childhood education programmes to detect the 70% of delayed readers whose failure cannot be explained by biological factors.

The reading skills of first graders are directly associated with their abilities to comprehend and produce speech prior to school entry²⁰. A recent study shows that, in sighted people, reading comprehension skills at school depend on the ability to transform the images of letters into sounds (i.e., phonemes)²¹. These basic speech skills need to be properly assessed and promoted during infancy and childhood.

Preventive interventions for language and communication evaluation have a better prognosis, at least with respect to reading skills, when starting in the first year of live²².

Promoting language initiatives

The intervention programmes inspired by cognitive psychology and cognitive neuroscience have expanded greatly in recent years. One of these programmes is called Parentese²³, which works with what we call infant-directed speech. When communicating with young children most adults spontaneously use infant-directed speech. Infant-directed speech has greater variations between high and low sounds, has longer vowels, longer syllables, exaggerated prosody (or melody), and more pauses, giving children the opportunity to take a turn and develop a response. Parentese also emphasizes the use of normal words (not infantilized) and contingent responses. This intervention seeks to facilitate the perception and processing of phonemes and words when they occur within sentences and phrases. The positive results of Parentese have been demonstrated by measuring the brain response in native phoneme distinction tasks²⁴, indicating that the systematic use of infant-directed speech and normal words shapes the plasticity of a young child’s brain. Finally, Parentese facilitates the learning of foreign languages²⁵ by improving the recognition and processing of foreign phonemes, syllables, and words.

Assessing language milestones

An important point here is to train early childhood educators not only to recognize language milestones but also to assess their achievement. The MacArthur-Bates Communicative Development Inventories (MB-CDIs)²⁶ is among the best tools we have for this purpose. MB-CDIs are parent-report instruments used to capture important information about children’s developing abilities in early language acquisition, including vocabulary comprehension, production, gestures, and grammar, between the ages of 6 and 36 months. Tools like this have proven very useful in evaluating infants’ and toddlers’ linguistic progress. However, there are still no gold-standard tests to evaluate linguistic abilities in young children.

At the global level, certain recent initiatives have described quantitatively and qualitatively the linguistic abilities of infants and young children. One of these is called “Wordbank”²⁷. Wordbank is an open database that archives the data from the MacArthur-Bates Communicative Development Inventories. It contains data from different languages and allows researchers from different cultures to analyse and compare them on an open access platform.

Early childhood educators may also benefit from basic training on other, non-linguistic capacities of young children, such as motor, social, and cognitive skills, and emotional development. Each of these abilities entails specific neuroscientific support and brain-based interventions. When such training is culturally adapted to local conditions, we believe it may help early childhood educators to more accurately and effectively evaluate the educational progress of the children in their care.

Message to early childhood educators

Every day new scientific data appears revealing new discoveries and updating previous knowledge about how the brain develops during early childhood. Because language is crucial for all academic achievements, the neuroscience of language can provide a powerful framework to understand how young children learn.

Neuroscience supports the findings obtained from several assessment studies designed to detect language difficulties among young children and design remedial interventions. Such knowledge must be regularly updated since neuroscience is a rapidly developing field of research.

Message to policymakers

Prevention of speech difficulties is a more effective way of fostering children’s potential than responsive interventions, and is more cost-effective for society. For instance, although hearing loss because of recurrent otitis media and chronic stress is fully preventable, this is rarely detected early. We believe that one of the most powerful actions to improve early detection of language difficulties is investing in continuing training of early childhood educators in cognitive neuroscience.

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