People judge faces with more visible eye whites as more trustworthy and attractive

A recent study published in the journal PLOS One suggests that the amount of the white of the eye visible in a person’s face can significantly influence how others perceive them. Researchers found that faces showing a larger portion of the eye’s white area tend to be judged as more trustworthy, attractive, sociable, and higher in social rank. These findings provide evidence that even subtle facial features play a role in shaping our instant social judgments of others.

Human faces serve as a rich source of social information in our daily lives. When people look at a face, they automatically form quick impressions about the person’s character, often without conscious thought. This rapid processing likely helps individuals navigate their social environments by quickly evaluating potential threats or positive social interactions. Within the face, the eye region tends to be particularly important for forming these early social judgments.

Past research has examined various features of the eye, such as pupil size and iris color. Scientists have also looked at the sclera, which is the white outer layer of the eyeball. Prior studies suggest that a brighter or lighter sclera might lead to more positive social evaluations. However, the exact role of scleral exposure, meaning the total visible amount of the white of the eye, has remained relatively unexplored.

Previous research on scleral exposure relied mostly on observational data without strictly controlling for other facial features. This made it difficult to determine whether the visible white of the eye was actually driving the social judgments or if other traits were responsible. A research team composed of Mathias Boyer-Brosseau, Simon Rigoulot, and Sébastien Hétu set out to address this gap. The authors designed an experiment to systematically manipulate the visible sclera area while keeping other facial details constant.

The researchers conducted their study using an online survey platform. They initially recruited 200 participants from the United States and Canada through Amazon Mechanical Turk, a popular online crowdsourcing platform. After removing participants who failed attention checks or provided unusual responses, the final sample included 162 adults from the United States. The group consisted of 107 men and 55 women with an average age of about 39 years, the large majority of whom identified as White.

During the experiment, participants viewed a series of 100 photographs of faces with neutral expressions. These images were taken from an established collection of photographs called the Karolinska Directed Emotional Faces database. The research team digitally altered the eye region of each face to create two different versions. Half of the faces were modified to show a small amount of scleral exposure, and the other half were modified to display a large amount of scleral exposure.

To ensure the images looked natural, the scientists used precise area measurements. They calculated the Scleral Area Ratio, which is the percentage of the white area compared to the total visible eye area. The small exposure models featured a scleral area of about 31.5 percent. The large exposure models featured an area of about 43.8 percent, avoiding extremely unusual proportions that might look unrealistic.

Below each image, participants used a 10-point scale to answer four specific questions. The questions asked how much they would trust the person, whether they would interact with them, and if they found them physically attractive. A fourth question asked participants to estimate the social rank of the person within society. The survey was self-paced, allowing participants to take their time evaluating each face.

The researchers found that scleral exposure had a consistent effect across all four categories of social judgment. Faces with a larger exposed scleral area received higher ratings for trustworthiness, attractiveness, sociability, and social rank. In other words, when a face displayed more of the white of the eyes, participants tended to view that person in a much more positive light compared to identical faces with smaller sclerae.

This preference for larger scleral exposure was universal across both male and female participants. The effect also applied equally to photographs of male and female faces. This absence of sex-based differences suggests that a highly visible sclera operates as a general social cue rather than a feature tied strictly to mating preferences. Aside from the sclera findings, the researchers noted that female faces were generally rated more positively than male faces by all participants, a difference that was especially pronounced among female raters.

The authors suggest a few possible explanations for why humans might prefer faces with larger sclerae. One idea is that a highly visible white area makes it easier to follow a person’s gaze. Gaze following is an essential part of human interaction, as it helps people infer where someone’s attention is directed. This allows individuals to interpret implicit attitudes and better predict another person’s behavior.

Another possible explanation involves age-related changes in the face. The overall visibility of the eye naturally changes over a person’s lifespan. Scleral exposure typically peaks in the early twenties and gradually reduces in later adulthood as the tissues around the eye soften. Because of this, a larger visible white area might serve as an underlying signal of youthfulness, vitality, and good health. This concept relates to neoteny, which is a process where juvenile or youthful physical traits are retained into adulthood.

The study presents a few limitations that should be noted by readers. The participants and the photographed faces were predominantly White, meaning these effects might reflect population-specific trends. Future research is needed to determine if this preference for larger sclerae extends to other populations and cultural groups. Addressing this lack of diversity will help scientists understand if the phenomenon is a universal human trait or shaped by specific cultural environments.

Additionally, the digital modifications increased the overall size of the eye to achieve the larger scleral exposure. It is possible that the sheer size of the eye, rather than just the white area, contributed to the positive social ratings. The authors note that completely separating the size of the white area from the total eye size is difficult without making the image look unnatural. Future studies might use advanced geometric shape modeling to isolate these specific variables.

Unintended emotional signals could also have influenced the participants during the rating task. Faces with smaller scleral exposure might have been unconsciously perceived as narrowing their eyes, which humans sometimes associate with negative emotions like anger or disgust. Even though all faces started with a neutral expression, the size of the eye opening might have slightly altered the perceived emotional state. Measuring how participants interpret the emotions of the modified faces could help clarify this issue in future experiments.

The authors also acknowledge that facial features do not operate in a vacuum. In everyday life, the white of the eye interacts with pupil size, iris brightness, and other facial features. The researchers point out that analyzing these traits together will provide a more realistic picture of how social perception works. In addition, the study noted a high correlation between the four social categories.

Because of this correlation, participants who rated a face as attractive also tended to rate it as trustworthy and sociable. This overlap is often referred to as the attractiveness halo effect, which is a psychological bias where a positive impression in one area influences opinions in other areas. Disentangling these overlapping judgments remains a complicated task for psychologists. Despite these challenges, the experiment provides evidence that the simple amount of visible eye white tends to sway our initial social opinions.

The study, “Scleral exposure influences social judgments of trustworthiness, attractiveness, sociability, and social rank in White faces,” was authored by Mathias Boyer-Brosseau, Simon Rigoulot, and Sébastien Hétu.