Scientists examine neurobiology of pragmatic reasoning

An international team including scientists from HSE University has investigated the brain's ability to comprehend hidden meanings in spoken messages. Using fMRI, the researchers found that unambiguous meanings activate brain regions involved in decision-making, whereas processing complex and ambiguous utterances engages regions responsible for analysing context and the speaker's intentions. The more complex the task, the greater the interaction between these regions, enabling the brain to decipher the meaning. The study has been published in NeuroImage.

Everyone has likely encountered a situation where the words spoken by their conversation partner did not align with their intended message. We can understand innuendos, irony, and sarcasm, even when the spoken words formally convey the opposite meaning. In cognitive science, this process is known as pragmatic reasoning—the ability to infer meaning from context, even when it is not explicitly expressed.

An international team of scientists conducted a study to uncover how the brain processes such situations. The study participants played a reference game, an experimental method used to investigate how people interpret ambiguous messages. In each trial, participants saw four expressible features and three monsters on the screen—a potato monster, an eggplant monster, and a pear monster. Each monster wore an accessory: a blue hat, a red hat, or a yellow scarf. The speaker sent a message highlighted by a yellow rectangle, such as 'red hat.' Participants had to determine which character was implied, but the clue was not always unambiguous, and the correct answer depended on the context. The experiment had three levels of complexity: simple, complex, and unambiguous, with the latter serving as the baseline condition. There were a total of 96 trials, with 32 trials for each level.

To identify which regions of the brain are involved in the interpretation process, the scientists recorded the participants' brain activity using functional magnetic resonance imaging (fMRI). This neuroimaging method makes it possible to study brain activity in real time. The authors of the paper also developed six computer models to characterise participants' behaviour and the strategies they use to interpret the information.

Their findings reveal that when a participant quickly understood the intended meaning of a phrase and was confident in their answer, the ventromedial prefrontal cortex (vmPFC), involved in decision-making, and the ventral striatum (VS), associated with the feeling of having made the right choice, were active.

However, when the meaning of an utterance was ambiguous, the brain activated other regions: the dorsomedial prefrontal cortex (dmPFC), which analyses the interlocutor's intentions and helps make sense of complex situations; the anterior insula (AI), which responds to uncertainty and tension by contributing to the generation of emotions; and the inferior frontal gyrus (IFG), responsible for language processing. The more complex the task, the more actively these regions interacted, helping the brain correctly interpret the meaning.

The researchers also found that the ability to understand others' thoughts and emotions contributed to successful performance. Participants who performed better exhibited stronger functional connectivity between the prefrontal cortex and the anterior insular cortex, indicating greater flexibility in their reasoning. Previously, pragmatic reasoning was studied within the framework of general models that involve common cognitive mechanisms. However, this study reveals that interpretation strategies can differ among individuals.

Mario Martinez-Saito

'Language comprehension is not just a matter of intelligence or memory. Our brain uses a complex system that integrates language, social cognition, and context analysis,' explains Mario Martinez-Saito, Research Fellow at the HSE International Laboratory of Social Neurobiology. 'The results obtained could also have practical applications. Perhaps, thanks to such research, your voice assistant will finally be able to distinguish between sincere praise and sarcasm.'