Study sheds light on the fundamental mechanism underlying judgments of facial attractiveness

A new study indicates that humans mentally represent faces relative to an ideal concept of a face, which serves as a reference point for their perception of facial typicality and attractiveness. The findings have been published in Cognitive Psychology.

Previous research has demonstrated that the perceived attractiveness of someone’s face can affect how intelligent, competent, and desirable they seem to others. Understanding how people perceive and recognize faces can help us understand how this process affects our social interactions.

“I am interested in how humans mentally represent information and how this affects our perception of the world. Faces are a good case study for this general question because humans are very good at perceiving and recognizing faces due to their special relevance in human social perception and interaction,” said study author Logan Trujillo, an associate professor of psychology at Texas State University.

The researchers used computational models and human judgments of the typicality and attractiveness of 100 young adult Caucasian female faces to compare various mental representation theories regarding the perception of facial attractiveness.

The researchers first had 48 undergraduates rate the typicality of each face on a scale of 1 to 7 and then rate the attractiveness of the faces on the same scale. Facial typicality was defined as the degree to which an individual face is a representative example of the face category to which that face belongs, while facial attractiveness was defined as the physical appeal and aesthetic beauty of a face.

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In a second study, the researchers presented 495 pairs of faces twice to participants who were asked to judge their similarity using a scale of 1 to 7. The pairs of faces were presented randomly on a computer screen. Before the task, participants were presented with the 100 faces for 1 second each to familiarize themselves with the set. Participants were instructed to base their ratings on the typicality of each face and ignore other factors, and to use the full range of the scale. The second study included 80 undergraduates.

The researchers found that perceived typicality and perceived attractiveness were positively related to each other.

Two popular theories of face recognition are prototype-based representation and exemplar-based representation. Both are applied within the face space heuristic approach, which represents facial features as locations within a multidimensional “face space.” Prototype-based representation encodes faces as vectors in the face space defined with respect to a norm or prototype located at the center of the space. In contrast, exemplar-based representation encodes faces by their location in face space relative to exemplars of previously experienced faces.

But the researchers found evidence that an “ideal dimension model” provided the best explanation for the data, indicating that participants had a mental ideal of what a representative face should look like. This ideal face served as a reference point for their perception of the faces presented in the study.

“Our findings suggest that when perceiving faces, humans mentally represent them relative to an ideal concept of a face, which is a hypothetically perfect representative face that specifies what a particular kind or population of faces should look like,” Trujillo said. “Such an ideal face is presumably developed within an individual’s mind through experience with a population of faces.”

But the researcher noted that “a major caveat of our study is that we only utilized Caucasian female faces. Additional research is needed to see how our results generalize to other populations of faces.”

The study, “Facial typicality and attractiveness reflect an ideal dimension of face structure“, was authored by Logan T. Trujillo and Erin M. Anderson.