By Hayden Nelson, C2ST Intern, University of Chicago

Did you know your smile is one of the most powerful social signals you have? Or that the simple act of smiling can change your brain chemistry, and even make strangers like you more? It’s true! Smiles aren’t just friendly gestures, they’re complex psychological signals that influence how we feel and how others perceive us. And what’s more interesting is that this all happens without us even noticing. Our brains respond to smiles automatically, shaping our impressions and emotional responses in a split second. 

There is a fascinating science behind smiles, from the subtle ways they communicate emotion, to the surprising effects they have on our minds and social interactions. In a world where so much of our communication happens instantly through screens, understanding the psychology of a simple smile can tell us more than we might expect.

When we smile, our brain releases neurotransmitters like dopamine and serotonin, chemicals responsible for happiness and relaxation. These “feel-good” chemicals improve our mood almost instantly, even if the smile is just a small one. Smiling also lowers cortisol levels, the hormone linked to stress. That means that even a forced smile can calm your body and trick your brain into feeling better, a psychological phenomenon known as the facial feedback hypothesis. This is the idea that our facial expressions can influence our emotions. Smiling also connects us to others through mirror neurons, which are brain cells that fire both when we perform an action and when we see someone else perform it. When we see someone smile, our brain often mirrors the expression without us realizing it. That’s why smiles are contagious. They spread positivity simply through observation.

Smiles are also powerful social signals, shaping first impressions and relationships before words are even exchanged. People who smile are usually perceived as more trustworthy, competent, and approachable. It’s a subtle but important form of nonverbal communication that can influence anything from job interviews to first dates. Smiling can also help others feel safe and valued, triggering a social response that encourages personal connection. 

However, not all smiles are interpreted the same way across cultures. In some places, smiling openly is a sign of friendliness and honesty; in others, it may be viewed as insincere or overly casual. Across certain European cultures, like Norwegian, Russian, and Polish communities, smiling at a stranger without reason can be considered insane or idiotic. A well known Russian proverb states, “smiling with no reason is a sign of stupidity”. The opposite is true in America, where a smile is seen as a friendly or polite gesture. However the frequency that Americans smile sometimes leads people from other cultures to find the smiles ingenuine or fake. These cultural nuances show how deeply smiles are embedded in our social norms, and reminds us that even something as universal as a smile can carry different social messages. What’s considered warm in one society might seem unusual in another.

But our smiles aren’t just psychological or social tools, they’re also reflections of how we feel about ourselves. People who feel insecure about their teeth or appearance often smile less, which can lead to a drop in confidence and fewer social interactions. Psychologists call this a feedback loop: when we smile less, we feel less positive, and when we feel less positive, we’re even less likely to smile. Over time, this loop can subtly affect our mental health and quality of life. The good news is that it’s a loop that can be reversed. Taking care of your oral health can boost confidence and make you more likely to smile freely and shift the loop in a positive direction. Even small actions like practicing smiling in the mirror or becoming more aware of your expressions throughout the day can help retrain your brain to smile more. The moment you start smiling more, the psychological benefits begin unfolding. It is one of the simplest ways to shift your mood.

At the end of the day, a smile is much more than just a friendly expression. It is a psychological tool, social connector, and a reflection of how we feel about ourselves. Smiles speak before words, shaping your mood, personal connections, and perception of the world. They’re small actions that have big psychological powers. They’re capable of easing stress, building trust, and strengthening bonds. So next time you catch yourself smiling, remember that it’s more than just a facial expression. It’s your brain, your emotions, and your social self working together. 

By Edita Music, C2ST Intern, Illinois Institute of Technology

We’ve all heard of cause and effect, but what if our universe doesn’t actually follow this principle? That’s the question behind a recent physics study conducted by Dr. Julia Mossbridge at the Mossbridge Institute, who spent a year recording how tiny particles of light (photons) behave inside a dark, sealed box. Her goal was to test something that could be the plot of a science fiction movie: could information about the future somehow show up in experiments done in the present? The phenomenon she studied is called the “causally ambiguous duration sorting effect” or CADS for short. In simpler terms, it’s a hint that the world around us may sometimes blur the line between “before” and “after.”

Continue reading “The Curious Case of the CADs Effect: Is Time Travel Actually Real?”

By Donnisa Edmonds, C2ST Intern, University of Chicago

Since the launch of ChatGPT in 2022, many people have wondered about the long-term impact of generative AI on our ability to remember information, communicate through writing, and think critically. This June, a research group from MIT’s media lab published one of the first studies to address these questions in “Your Brain on ChatGPT: Accumulation of Cognitive Debt when Using an AI Assistant for Essay Writing Task.” 

Continue reading “Your Brain on ChatGPT: A Cognitive Neuroscientist’s Breakdown”

By Rowan Dunbar, C2ST Intern, University of Illinois Chicago

This past summer, I found myself teaching a classroom full of fourth through eighth graders. When I asked them, “What do engineers do?” Their answers were spot on: “Engineers make things to help people.” This answer is not too different from the one I heard throughout my K-12 education; however, as I get further into my education as a biomedical engineer, I find myself circling back to this definition with more and more questions. Do we help folks who need it?  How do we help them? These questions are even more critical in the medical field where people’s health and wellbeing are on the line. This is where the concepts of Verification and Validation (V&V) come in. Every medical device goes through a rigorous process involving regulatory oversight, review, and iteration before it gets released; this process is ongoing even after a product is released!  

Continue reading “Beyond Validation: Are Medical Devices Meeting Our Needs?”

By Hayden Nelson, C2ST Intern, University of Chicago

Have you ever wondered why your teeth aren’t perfectly white? Or why coffee, tea, and red wine seem to leave their mark? The answer comes down to chemistry. Every sip and snack you take sparks tiny chemical reactions inside your mouth. That morning coffee? Its dark pigment slips into the tiny grooves in the surface of your teeth. The glass of red wine at dinner? Same story. Our teeth might look simple, but they’re surprisingly complex structures that react to what we eat and drink every day. Despite their smooth look, our teeth are actually made up of layers of tightly packed minerals with tiny pores that absorb pigments from the foods and drinks we love. Understanding the chemistry behind your teeth and their stains helps explain why some smiles stay bright while others fade, and how everyday choices can make a microscopic difference.

Continue reading “The Chemistry of Your Smile: What Coffee, Wine, and Foods Are Really Doing to Your Teeth”

By Edita Music, C2ST Intern, Illinois Institute of Technology

Genetic testing. It sounds like something that can only be done in a fancy laboratory with microscopes and researchers in white coats. But it’s also something millions of people have done from the comfort of their living rooms.

Continue reading “From the Lab to the Living Room: The Ethics of At-Home DNA Testing”