Cognitive scientists reveal how our brain deals with multiple meanings of polysemous words

The research findings are published in Scientific Reports.

The scientists came to this conclusion during the current functional MRI event‑related study. There were 48 volunteers (20 males, 28 females) who took part in the study. Each of the participants was asked to perform a special task. The experimental task was to complete Russian adjective-noun fragments with missing letters, for example, the fragments like s-khoe vi-o or s-khoe -ino. The adjective could always be completed in only one way (‘sukhoe’ — ‘dry’), and for nouns, it was most often required to choose one of several possible options (‘vino’ or ‘kino’ — ‘wine’ or ‘cinema’). In the study, each participant was asked to complete 96 adjective-noun fragments.

Professor Tatiana Chernigovskaya, Director of the Institute for Cognitive Studies at St Petersburg University, explained that the researchers recorded the research subjects’ functional brains activity during the performance of the tasks.

Functional magnetic resonance imaging (fMRI) was used for this. This method not only makes it possible to obtain information about the activation or deactivation of brain structures during the studied activity, but it also measures and maps brain system activity.

Professor Tatiana Chernigovskaya, Director of the Institute for Cognitive Studies at St Petersburg University, Corresponding Member of the Russian Academy of Education

‘Moreover, the functional MRI method makes it possible to register brain activity at the very moment when the meaning for an ambiguous word is selected. This was impossible to measure in solely psychological or psycholinguistic studies,’ Professor Chernigovskaya noted.

The experiment revealed that in situations when we have to process ambiguous information to select one of the multiple meanings for an ambiguous word, inhibitory processes are recruited. Firstly, the researchers observed reduction of the hippocampal activity. Hippocampus is responsible for language processing and associated with retrieval of concepts from semantic memory. Secondly, they noticed that the hippocampus ‘switched off’ from system interaction with other brain structures. Consequently, non-selected solutions of ambiguous fragments were automatically ‘deleted’ from the awareness. This made it possible to select the solution and thus resolve the ambiguity.

The research findings contribute to advancing fundamental knowledge about the human brain, human behaviour, memory, attention, as well as human information processing. These data can be used in a large number of application areas where the issue of adequate information processing and decision making — including under stress — is important.

Professor Tatiana Chernigovskaya

Tatiana Chernigovskaya emphasised that the study will facilitate understanding of how a human manages to navigate the current reality. ‘We live in a world where almost all visual images, linguistic expressions and other objects are inherently ambiguous or uncertain. We are continuously engaged in the process of ambiguity resolution. We are constantly faced with ambiguous information that requires the selection of one of its options. At the same time, a human can be aware of only one meaning at a time. Faced with ambiguity, the cognitive system decides on what to be aware of and what not. How does the brain deals with multiple meanings of ambiguous stimuli? What brain mechanisms are involved in implicit processing of the non-selected meanings? How does the brain manage to resolve ambiguities? This is what our study is about,’ Professor Chernigovskaya concluded.