Chocolate lovers’ brains: How familiarity influences reward processing

A neuroimaging study on how humans respond to chocolate revealed that the human brain reacts faster to images of familiar chocolates compared to those of unfamiliar chocolates. However, choosing unfamiliar chocolates over familiar ones elicited stronger brain responses in the bilateral inferior frontal gyrus and right caudate head regions. The research was published in the Journal of Neuroimaging.

When a person eats something delicious or achieves success, they typically experience feelings of pleasure. These feelings are produced by the brain’s reward system, a network of structures responsible for regulating feelings of pleasure and motivation. Key components of this system are located in the nucleus accumbens, the ventral tegmental area, and the prefrontal cortex.

When a person experiences something rewarding, this system releases dopamine, a neurotransmitter that signals pleasure. This dopamine release activates specific neural structures, making the person more likely to repeat the behavior that led to the dopamine release, thereby experiencing pleasure again.

The prefrontal cortex helps regulate and control these reward-driven behaviors by making decisions and weighing the consequences. Dysfunction in the brain reward system can lead to addiction, where the system becomes hijacked by substances or behaviors that trigger excessive dopamine release, leading to compulsive actions. For this reason, understanding how the brain reward system functions attracts a lot of research interest. These findings might be crucial for developing treatments for various forms of addictions and other disorders related to motivation and reward.

Study author Senal Peiris and his colleagues examined how familiar and unfamiliar chocolate brands influence reward processing for people who love chocolate. They focused on wanting the chocolate, which is associated with craving, and on liking it, which is associated with pleasurable experiences.

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They hypothesized that chocolate lovers would have increased neural activity in the ventromedial prefrontal cortex when selecting familiar chocolate brands, but show reduced neural activity in the dorsolateral prefrontal cortex when selecting unfamiliar chocolate brands because this decision-making is based on reasoning.

In reward processing, these two brain areas have somewhat different functions. The ventromedial prefrontal cortex is believed to be primarily involved in evaluating the value of rewards and making decisions based on those values, while the dorsolateral prefrontal cortex is believed to be involved in reasoning-based decisions about rewards by integrating information and applying cognitive control to make thoughtful, goal-oriented choices.

The study participants were 24 healthy adults aged between 19 and 45 years, with an average age of 25. They volunteered for the study by responding to an advertisement recruiting “Chocolate lovers” and received $50 gift cards for their participation. For selection purposes, the researchers had candidates complete an assessment that characterizes preferences for chocolates (the Chocolate Questionnaire), ensuring all participants were indeed chocolate lovers. Selected participants completed two experiments while undergoing functional magnetic resonance imaging.

Before the start of these experiments, participants were asked to list their three favorite chocolate brands, followed by all brands of chocolate they could remember. Twenty-three of the 24 participants listed Hershey’s among their top three favorites, followed by Dove (listed by 17 participants among the top 3). Because of this, the researchers used Hershey’s and Dove to create a category of familiar chocolates for the experiments.

Neither Perugina nor Landmark Confections appeared on either list for any of the participants, and participants confirmed that these two brands (popular in Europe but not in the United States) were unfamiliar brands of chocolate and that they had never tasted them before. The researchers based the unfamiliar chocolate category on these two brands.

In the first experiment, participants viewed pictures of familiar and unfamiliar chocolates while undergoing functional magnetic resonance imaging and rated how much they craved and liked each brand. Each image was presented 14 times, for a total of 56 trials. In the second experiment, participants viewed the same images but paired so that one familiar and one unfamiliar chocolate type were shown side by side. Participants had to indicate their preference. There were 24 trials in this experiment.

Results showed that participants craved and liked familiar chocolates more. In the preference experiment, they chose familiar chocolates in 62% of the trials. When the researchers compared how much participants craved and liked chocolates and whether they chose them in the preference experiment, results showed that participants who reported craving unfamiliar chocolates more were also more likely to select them over familiar chocolates. On the other hand, participants who liked familiar chocolates more were more likely to choose them over unfamiliar chocolates.

Neuroimaging data showed that when just viewing pictures of chocolates, the right posterior middle temporal gyrus and left superior occipital gyrus regions were more strongly activated by unfamiliar chocolates. The left and right inferior frontal gyrus and right caudate head were more strongly activated in individuals who chose unfamiliar chocolates. The researchers believe that these regions are part of the neural network recruited when a person chooses unfamiliar chocolates over familiar ones. Neural responses were faster to images of familiar chocolates.

“The choices for branded chocolate products are driven by higher subjective reward ratings and lower neural processing demands,” the researchers concluded.

The study sheds light on how brain responses depend on the familiarity of chocolate brands. However, it also has limitations that need to be considered. Notably, the study was based on a very small number of participants, and conclusions might be limited to chocolate lovers. Results might not be the same in individuals whose preferences for chocolates are less pronounced.

The paper, “Neural correlates of chocolate brand preference: A functional MRI study,” was authored by Senal Peiris, Michael J. Tobia, Andrew Smith, Emily Grun, Rommy Elyan, Paul J. Eslinger, Qing X. Yang, and Prasanna Karunanayaka.