Russian scientists have discovered a simple and reliable method to understand how people perceive different tastes.

The study has been published in the journal Food Quality and Preference. How do we perceive taste? Why do some foods bring pleasure while others evoke indifference or even rejection? Science already knows that this is linked to the activation of specific areas of the brain that process our perception of taste and emotions. For instance, a sweet taste may stimulate areas associated with pleasure, whereas a bitter taste may activate regions responsible for vigilance and protection against potential danger.

To understand these processes, scientists employ complex and costly methods. Functional MRI is considered the most effective among them. It allows researchers to "look" deep into the brain and see which parts are activated when perceiving different tastes. However, these technologies require strict conditions: participants must lie still, which can interfere with their ability to taste food.

Researchers from HSE University have successfully demonstrated how near-infrared spectroscopy (fNIRS) can be used to understand how people perceive different tastes. This method is cheaper, easier to implement, and allows participants to be in a natural position, such as sitting at a table. However, fNIRS has been rarely used in taste research, and its potential remains largely unexplored.

During the experiment, scientists not only tested how effectively fNIRS captures the brain's response to taste but also analyzed how this activity relates to other physiological processes. Researchers measured heart rate, skin response (electrodermal activity), and recorded movements of facial muscles to obtain a complete picture of how we react to the taste of food.

“We tested the response to two types of food in 36 volunteers: a pleasant one — fruit puree, and a neutral one — vegetable puree. The choice of puree was not random: the soft texture helped avoid data distortion that could arise from chewing. As expected, the vegetable puree did not elicit excitement, but it would be incorrect to label it as unpleasant food. If we rank all food, it divides into pleasant and neutral categories. There is essentially no such thing as truly 'unpleasant' food,” explains one of the study's authors, researcher at the Institute of Cognitive Neuroscience at HSE University, Yulia Yeremenko.

The researchers made significant progress in understanding how the brain reacts to food. One of the main achievements was the use of a special setup for near-infrared spectroscopy that allowed them to focus on the insula area. This part of the brain, located deep within the temporal lobe, is responsible for taste perception. Typically, studying it requires magnetic resonance imaging (MRI), but the modification of fNIRS enabled the examination of brain function with less complex equipment.

The results showed that pleasant food activated the insula in the left hemisphere of the brain, which is associated with positive emotions and a sense of pleasure. In contrast, the neutral taste triggered activation in the right precentral gyrus. This phenomenon can be explained by interhemispheric asymmetry — a characteristic of brain function where each hemisphere processes different types of stimuli. The left hemisphere primarily responds to positive emotions, while the right is associated with processing negative stimuli and avoidance reactions. Thus, the vegetable puree elicited unpleasant emotions in people.

The researchers also observed how food perception was reflected on the faces of the experiment participants. Pleasant food activated the zygomaticus — the major muscle responsible for smiling. Conversely, when consuming neutral food, the corrugator — the muscle that furrows the brow — was activated before swallowing.

These physiological reactions are so reliable that they can be used for an objective assessment of taste preferences. Unlike verbal feedback, which can be subjective or insincere, facial reactions honestly reveal whether a person likes the food or not. Moreover, the methodology is simple and effective: testing 40–50 people is sufficient to draw conclusions. Such data can be beneficial for food companies looking to improve their products.

“We are actively researching the impact of neurophysiological stimuli on food perception. For instance, we have developed a feeding setup at our institute that is already integrated with neurophysiological equipment. This setup is synchronized with the experimental design, allowing us to analyze the influence of packaging or price on taste perception. Additionally, my colleagues and I run a neuromarketing channel, where we discuss how knowledge of the brain can be used for effective product and service promotion, as well as for a deeper understanding of consumer motives and behavior,” shares Yulia Yeremenko.

The study was conducted as part of the strategic project "Sustainable Brain: Neurocognitive Technologies for Adaptation, Learning, Development, and Rehabilitation of Humans in a Changing Environment" ("Priority-2030").