The face you walked into the room with this morning was being read, by every person who looked at you, in approximately one hundred milliseconds — about a tenth of a second, faster than any conscious thought. The reading was not primarily about the features that took your DNA twenty years to assemble. The bones of your face, the colour of your eyes, the shape of your jaw, the symmetry of your features — these all contributed to the judgement, but they were not, on the available evidence, the only ingredients of it. A substantial part of how attractive any individual stranger perceived you to be, in the brief moment before they had any other information about you, was almost certainly whether you appeared to be having a good time. A genuine smile, animated expression, and the visible signs of a person enjoying being where they are produce, in the moment of first impression, attractiveness boosts that can rival what carefully selected clothing, makeup, or grooming can plausibly achieve.
According to a 2014 paper by Jessika Golle, Fred Mast, and Janek Lobmaier published in Cognition and Emotion titled “Something to smile about: The interrelationship between attractiveness and emotional expression”, the social effect of smiling on stranger-rated attractiveness has been replicated across enough independent studies and across enough cultural contexts to be considered one of the more robust findings in social psychology. Smiling faces are rated more attractive than neutral faces of the same person, across both sexes, across multiple age ranges, and across essentially every population that has been examined. The neuroimaging literature has identified the underlying mechanism: when human observers see a smiling face, the medial orbitofrontal cortex — a region of the brain involved in reward processing and the assignment of positive value to stimuli — shows a substantially stronger response than when the same observer sees a neutral face. The smiling face is, in a literal sense, registering in the observer’s brain as more rewarding to look at.
What kind of smile actually works
The specific type of smile matters substantially. As reported by a peer-reviewed PMC review of smile research and the broader perception literature, the most extensively studied distinction in the smile literature is between what researchers call Duchenne smiles and non-Duchenne smiles. The Duchenne smile, named after the 19th-century French neurologist Guillaume Duchenne who first characterised it, activates two distinct sets of facial muscles: the zygomatic major, which pulls up the corners of the mouth, and the orbicularis oculi, which creates the small crinkles around the outer corners of the eyes. Both muscle activations occur involuntarily when a person is genuinely amused or pleased. The non-Duchenne smile activates only the mouth corners and is the kind of polite, social smile produced on demand for photographs or to acknowledge a casual greeting.
The two types of smile are perceived very differently by observers, even though most people cannot articulate exactly what the difference is when they see one. Duchenne smiles register as genuine, warm, trustworthy, and substantially more attractive. Non-Duchenne smiles register as polite at best, performative or insincere at worst, and produce far smaller boosts to attractiveness ratings. The discrimination is automatic and is operating in the observer’s brain at the level of unconscious pattern recognition rather than conscious analysis. This is the underlying reason why the standard advice to “smile more in photos” often produces mediocre results in practice: the smiles are non-Duchenne. The viewer’s brain registers the difference even when the viewer cannot consciously identify what is wrong with the expression.
Why the effect is so large
Per a 2023 study in Evolutionary Human Sciences examining how smiling expressions interact with facial features in attractiveness judgements, the magnitude of the smiling-on-attractiveness effect is large enough to substantially affect outcomes in real-world social contexts. Across studies, happy facial expressions consistently produce the highest attractiveness ratings of any expression tested; angry expressions produce the lowest. The effect appears in both sexes but is particularly pronounced for ratings of female faces, where smiling can shift attractiveness ratings by amounts comparable to the difference between an averagely-rated face and a substantially above-average face. Even male facial masculinity — which interacts in complex ways with attractiveness preferences — is moderated by smiling: smiling reduces the avoidance response some women show toward strongly masculinised male faces.
The evolutionary and social explanation for this effect is, in the relevant literature, fairly direct. A smile is one of the few human expressions that is broadly cross-cultural — recognised across nearly every population that has been tested — and that consistently signals friendliness, low threat, willingness to engage, and positive emotional state. For an observer making rapid social judgements about whether to approach a stranger, the smile is a substantial piece of information: it indicates that the encounter is likely to go well, that the person on the other side is in a positive frame of mind, and that initial overtures will probably be reciprocated. The attractiveness boost is, in this account, the observer’s brain doing what brains do — bundling the information about the smile into a single quick-summary judgement about whether this stranger is worth engaging with. The summary judgement, in shorthand, comes back as “attractive.”
What the framework does not claim
Intellectual honesty requires noting the limits of the smiling-as-attractiveness effect. The research does not show that smiling can substitute for every other physical or social factor in attractiveness ratings. As covered by a 2025 review at All About Psychology on the broader smile-attractiveness literature, static physical features — facial structure, body shape, height, age, grooming — still contribute substantially to first-impression attractiveness ratings, and the smile effect is best understood as a substantial modifier of these underlying factors rather than as a replacement for them. A smiling face is more attractive than the same face not smiling. A smiling person is generally more approachable than a neutral one. Whether the smiling person is, in absolute terms, more attractive than a non-smiling person with substantially different underlying physical features is a question the research does not consistently answer.
What the research does support is a more specific and more practically useful claim. For any given person, in any given moment, the version of that person who appears to be genuinely enjoying themselves is going to be perceived as more attractive than the same person looking flat, distracted, or unhappy. The variable that each individual has the most direct control over, in the seconds before a first impression forms, is not their face or their body — those are mostly fixed at the moment of the encounter. The variable that is actually within their control is their expression, their visible emotional state, the degree to which they appear genuinely engaged with what is happening around them. The research consistently suggests that this variable, despite being the one most readily modifiable, is one of the larger factors that the observer’s brain weights when assigning the first-impression attractiveness rating. Looking like a person who is glad to be where they are turns out to be, by every available measure, a substantial part of what other people are responding to when they form their first impression of you.
