New research published in the journal Perception shows that the colour of a person’s hair and the background behind them can alter how observers judge their skin, with darker hair and a black backdrop tending to make facial skin appear more even. The study, led by psychologist Carlota Batres of Franklin & Marshall College and co-authored with Richard Russell of Gettysburg College, used two experiments to test whether surrounding visual contrast can shift perceptions of skin evenness, a factor linked to perceptions of health and attractiveness.
Perceived skin evenness refers to how uniform a person’s skin colour and surface texture appear to observers. When skin is evenly toned and free of blemishes, observers tend to judge the face as younger, healthier, and more attractive. Beyond physical appeal, smooth skin is often linked by observers to traits such as trustworthiness and competence, assumptions that carry considerable social weight in daily life.
Researchers already know biological skin condition shapes appearance, but human perception is complex and affected by nearby features. Past work shows that increasing the visual contrast between skin and facial features like the eyes, lips and eyebrows can make the skin appear more even, even when makeup leaves the skin itself untouched.
“Previous research has found that increased contrast between skin and adjacent surfaces increases perceived skin evenness,” lead researcher Carlota Batres told PsyPost. “Our study aimed to examine whether this effect can be extended to situations where the entire face is left untouched and contrast is modified by increasing or decreasing the luminance of surfaces surrounding the face.”
The researchers propose that a basic brain mechanism known as contrast gain control underlies this effect. In simple terms, the brain evaluates brightness and texture for a region relative to its surroundings. The team sought to discover whether this mechanism operates over larger spatial distances by altering contrast outside the face—through hair lightness or background colour—to see if the eye is still tricked into perceiving more even skin.
Batres explained that the reach of contrast gain control was previously unclear: “The effects of contrast gain control are believed to operate within but not across cortical hypercolumns, meaning I was not sure this effect would be present across greater spatial expanses such as the contrast surrounding the face. In other words, previous studies have addressed contrast within the face, and here we aimed to address contrast outside the face.”
In the first experiment, the team used photographs of 45 white women aged between 19 and 79, all facing forward with neutral expressions. Faces were captured so the hair could be fully masked by an oval border, leaving only the facial skin and features visible. Each face was presented in two versions: one set against a high-contrast black oval background, and another against a low-contrast skin-coloured background created by averaging the cheeks’ skin tones. A total of 61 online participants viewed 90 images in random order and rated skin evenness on a seven-point scale, where one signified very uneven and seven signified very even.
Across the two background conditions, observers judged skin as more even against the black background. The average evenness score was 4.18 with the black background versus 3.95 with the skin-coloured background. The effect persisted whether the judged face belonged to a younger woman under 30 or an older woman over 30.
The second experiment sought a more natural adjustment. A new set of 41 white women aged 19 to 79 was photographed, this time with a clear boundary between hair and skin. Researchers created two versions for each image by subtly lightening or darkening the hair by equal amounts. A separate group of 80 online participants rated the 82 images on the same seven-point scale.
As with the background experiment, altering hair colour influenced perceived skin evenness. Faces with darker, artificially reddened hair were judged to have more even skin, with an average score of 4.06, compared with 4.01 for slightly lighter hair—a small difference of 0.05 points on the seven-point scale.
When results were broken down by age, the effect was not statistically significant for younger faces, whose skin was generally already quite uniform. For older faces, however, darker hair made the skin appear more even. The researchers suggest the milder hair adjustment in this experiment may explain why the effect was harder to detect in younger faces, while older faces with more uneven skin showed a clearer response.
Batres commented on the broader implications: “Many practices of grooming and personal decoration involve surfaces adjacent to the skin, such as hair, clothing, or other backgrounds, and the results of this study show that these social practices have perceptual consequences related to skin appearance.” She added that the contrast between the facial skin and surrounding surfaces—whether background colour or hair colour—influences perceived skin evenness.
The findings offer a potential scientific explanation for certain fashion and grooming preferences. It has long been observed that women are often rated more attractive when wearing black clothing; the study suggests this boost in appearance may partly arise from higher contrast with the skin, enhancing perceived skin evenness. Similarly, hair framing the face may increase visual contrast next to the skin, potentially boosting perceived skin health.
There are important caveats. The study used photographs of lightly pigmented white women, so the results may not automatically apply to faces of other races or genders. It remains unknown whether the same contrast trick works with darker skin tones or with different hair and background combinations.
Another limitation is the modest degree of hair adjustment in the second experiment; researchers kept to slight lightening or darkening within the same colour family. “Our hair manipulation was slight, and it would be interesting for future studies to further examine this effect,” Batres said.
Future work could explore more dramatic hair changes—such as shifting from blonde to black—to determine whether greater contrast yields a stronger illusion of skin evenness. The researchers also propose testing other common facial accessories, like glasses, hijabs, or jewellery, to see how they interact with skin perception.
The study, “Perceived skin evenness is influenced by background colour and hair colour,” was authored by Carlota Batres and Richard Russell.
