For several years, psychologists and neurobiologists at St Petersburg University have been engaged in research to gain an insight into which mechanism of word acquisition is the most effective. There are two main learning strategies: a direct explicit instruction and a contextually-driven implicit inference/deduction. Research shows that they both appear to be effective. The data obtained will help develop methods to teach the native language and foreign languages. Additionally, this may contribute to restoring the ability to communicate after brain injury. The research findings are published in Frontiers in Psychology.

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‘Acquisition of new words can be achieved through two main learning strategies. First, a direct explicit instruction that is usually associated with repetitive presentation, such as classroom instruction when we learn foreign languages at school. We are shown an object and told what it is called. Second, contextually-driven implicit inference/deduction,’ said one of the authors of the research project, Associate Professor in the Department of General Psychology at St Petersburg University, and a member of the Laboratory of Behavioural Neurodynamics at St Petersburg University Olga Shcherbakova.

Which mechanism of word acquisition is the most effective remains a largely debated topic in the scientific community today as does which neural mechanisms of word acquisition are involved, she said. Pursuing the aim to advance the studies into how we acquire new words to use in communication, researchers at the University attempted to develop an experimental audio-visual paradigm to fully balance all audio and visual features of the stimulus introduced to the subjects and cognitive load.

The first stage of the research project focused on selecting real-life words in the Russian language through a rigorous selection procedure. For example, these words must be nouns that are highly used in speech and denote well-known objects or animals. They should be similar in terms of their physical and psycholinguistic features and consist of three sounds and three letters. For example, ‘фен’ /fen/ (a hairdryer) or ‘мул’ /mul/ (a mule). The Russian language is diverse and rich, yet it was a hard nut to crack.

Afterwards the researchers took the beginning and the end from each real word and made up several hundred pseudowords by rearranging the pieces. Of this number, only those pseudowords were selected that did not sound similar to the words which already existed in the Russian language (otherwise they would be subconsciously perceived as meaningful and familiar). The resulting list included pseudowords that did not not exist in Russian, yet followed its rules, for example, ‘фел’ /fel/ or ‘мун’ /mun/. Additionally, they picked up the images of various objects and animals that were unknown to the subjects. For example, the images of ancient medical tools or rare deep-sea animals. This images were accompanied by the pseudowords during the practice session. All visual features of the images, including brightness and size, were under rigorous control.

The subjects had to answer ten questions that had pseudowords. For example, ‘There is a fel /fel/ in front of you. Have you memorised?’ or ‘Does the mun /mun/ have horns?’ Thus, the subjects learnt new words, how they sounded and what they meant in the context of audio-visual word acquisition.

‘To assess how our brain works before and after the practice sessions, we measured electric neuronal activity y a time-resolved imaging tool EEG. We registered so called evoked potentials, i.e. surges of coordinated neuronal activity, that appear in the neocortex in response to being exposed to familiar and unfamiliar words before and after the practice session,’ said Professor Yury Shtyrov, who is the first author of the research and Head of the Laboratory of Behavioural Neurodynamics at St Petersburg University where the research was carried out. ‘Moreover, the practice sessions were followed by the tasks that focused on how well the subjects acquired new word. Among them were tests to use fluently these words in communication, to recognise them by ear, and to understand what they meant.’

Analysing the obtained data resulted in admitting that both implicit and explicit ways of learning were equally effective. ‘We demonstrated that both ways of learning were effective, even after holding as few as 10 sessions. These results were also confirmed by the results we gained from performing three final tests,’ said the researchers. ‘Although our naïve concepts and the results of previous studies prove the opposite, both ways of learning have proved to be equally effective.’

Yet the neuronal mechanisms of language acquisition are different in implicit learning and explicit encoding. Electroencephalography was specifically aimed at investigating the neural bases of language learning and use. Although both ways of novel word acquisition are effective, the brain mechanisms are different. During the research, the scholars recorded different images of how the neuronal activity is distributed on the neocortex.

Implicit learning is primarily associated with the left hemisphere of the brain which is traditionally associated with language processing and use. This in no way is a statement against the traditional beliefs about how we use language in communication. Yet when it comes to explicit encoding, it is likely to activate the system across both hemispheres which is associated with how we perform functions and control attention. These mechanisms are assumed to have been acquired later during the evolution. They are more mature and complex in terms of how many resources we use to perform them. Scholars at the University are the first who were successful in proving it experimentally across the world.

Researchers expect that the data obtained have a great potential to be used for education purposes, and treatment and rehabilitation therapies for people who suffered brain injury. For example, deciding which method of learning to use in treating speech disorders after an ischemic stroke depends on which parts of the brain have been injured.

More information about research carried out by the scholars at the Laboratory of Behavioural Neurodynamics can be found in the magazine St Petersburg University.

Founded within the mega-grant of the Government of the Russian Federation that focused on the wide-ranging project ‘Cognitive Neurobiology of Learning and Language Perception Processes’ (No 14.W03.31.0010), the Laboratory of Behavioural Neurodynamics at St Petersburg University is headed by Professor Yury Shtyrov who graduated from St Petersburg University. He is a neurophysiologist and Head of the Laboratory of Magneto- and Electroencephalography at Aarhus University, Denmark. The Laboratory of Behavioural Neurodynamics focuses on researching into how the processes in our brain are interrelated to various psychic phenomena.