When we look at human faces, our brain has different responses depending on how attractive we find them, according to new research published in Biological Psychology. However, these responses are only observed when looking at faces of the gender that you are sexually attracted to.
The study also discovered that these responses to facial attractiveness occur in a specific sequence, which suggests that our brain goes through distinct stages of processing when evaluating how attractive a face is.
The authors of the new study were interested in studying the perception of attractiveness and its impact on how people are judged and treated. Previous studies have shown that attractive individuals are generally viewed more positively and are attributed with various positive qualities such as intelligence, sociability, and trustworthiness.
However, the neural basis of attractiveness perception is not well understood, and previous research using event-related potentials (ERPs) to study facial attractiveness had produced inconsistent results.
ERPs are patterns of electrical brain activity that are time-locked to specific events or stimuli, such as the presentation of a face. They provide a way to examine the brain’s activity and processing related to specific cognitive or perceptual events.
“Since the experience of liking something is so clearly different from that of disliking something, you would expect that the neural activity patterns of these experiences are clearly distinct too,” said study author Hans Revers, a PhD candidate at the Department of Cognitive Neuropsychology at Tilburg University. “Yet decades of research has not found consistent patterns in spite of ever more sophisticated imaging and analysis techniques. Possibly, the culprit is in the affect elicitation method.”
“Attractive and unattractive faces with neutral expressions are straightforward, unambiguous stimuli that trigger almost immediate feelings of liking or disliking, responses that are likely rooted in evolution. Facial attractiveness may therefore have some advantages over commonly used affect elicitation methods. However, only a few studies have reported on ERP effects to (un)attractive faces, with inconsistent results.”
In their new study, Revers and his colleagues sought to investigate how the brain responds to attractive and unattractive faces and whether these responses differ based on the preferred gender of the participants.
They recruited 63 healthy participants, mostly first-year psychology students, who viewed 252 color images of faces on a computer screen, which were carefully selected based on specific criteria such as minimal emotional expression and minimal makeup. The images were categorized into attractive, intermediate, and unattractive faces, with 40 images in each category for the experiment.
Participants rated the attractiveness of each face using a slider, and the ratings were used as independent variables for analyzing the neural responses. Physiological measurements, including EEG activity, were recorded during the experiment.
The researchers analyzed several ERP components of interest, including the P1, N1, P2, N2, N170, EPN, P300, and late positive potential (LPP). Each of these components represents a specific electrical response in the brain that occurs at different time intervals after stimulus presentation.
The LPP is one of the ERP components that was of particular interest in the study. The LPP reflects a sustained positive electrical potential over the scalp that occurs around 300-800 ms after stimulus onset. It has been associated with emotional and motivational processing.
The results showed that there were distinct ERP patterns associated with attractiveness perception.
“The processing of facial attractiveness appears to go through two separate stages. First, the salience of the faces is processed, those that we find very attractive or very unattractive elicit greater neural responses than the more neutral intermediate attractive faces,” Revers told PsyPost.
“Following this is the processing of valence, the most attractive faces elicit the greatest neural activation while the least attractive faces elicit the least activation. Importantly, this distinction is only apparent for faces of the preferred gender, indicating that relevance may be a prerequisite for the experience of valence.”
In the early LPP interval (450-850 ms), there was a salience effect, where both attractive and unattractive faces elicited larger brain responses compared to intermediate attractive faces. This effect was observed for the preferred gender faces.
This enhanced brain response to highly attractive and unattractive faces indicated that these faces stood out or captured the participants’ attention more than faces with intermediate attractiveness.
In the late LPP interval (from 1000 ms onward), there was a valence effect, where attractive faces elicited larger brain responses compared to unattractive faces. This effect was also specific to the preferred gender faces. This valence effect suggests that our brain processes attractive faces differently from unattractive faces, with attractive faces being associated with a more positive emotional response.
However, for the dispreferred gender faces, the valence effect was not observed in the late LPP interval.
The findings suggest that the brain processes facial attractiveness differently depending on the preferred gender of the participants. Faces of the preferred gender elicited both salience and valence effects, indicating a more conceptual processing of attractiveness. On the other hand, faces of the dispreferred gender evoked early differential responses, suggesting more perceptual evaluation of attractiveness.
“The finding of such a long-lasting strong valence effect is novel,” Revers noted. “Affective neuroimaging studies have commonly only found salience effects. Common practice of analyzing only the first 800 or 1000ms following stimulus onset may have prevented earlier studies from detecting valence effects. We advise future studies to explore latencies op to 3000ms.”
The study, “Neural responses to facial attractiveness: Event-related potentials differentiate between salience and valence effects“, was authored by Hans Revers, Katrijn Van Deun, Jean Vroomen, and Marcel Bastiaansen.
