The face, which is known as the index of mind, is as unique as fingerprints and can reveal a great deal of information about our health, personality, age, and feelings.
The transition into adulthood literally changes the way people see faces -- which includes showing a bias toward adult female faces as children, to preferring peer faces that match their own developmental stage in puberty.
This process is part of the social metamorphosis that prepares them to take on adult social roles, the study said.
"For the first time, the study has shown how puberty, not age, shapes humans' ability to recognise faces as they grow into adults," said Suzy Scherf, Assistant Professor at the Pennsylvania State University.
The findings showed that puberty shapes the subtle emergence of social behaviours that are important for adolescents' transition to adulthood.
"This likely happens due to hormones influencing the brain and the nervous system reorganisation that occurs during this time," Ms Scherf added.
For the study, the researchers recruited 116 adolescents and young adults -- all in the same age group -- and separated them into four pubertal groups depending on their stage of puberty.
Any differences in the way they responded to faces were related to their pubertal status, not their age. The participants were presented with 120 gray-scale photographs of male and female faces.
Using a computerised game, the researchers then measured their face-recognition ability.
After studying 10 target faces with neutral expressions, participants were shown another set of 20 faces with happy expressions and had to identify whether they had seen each face previously or if they were new.
The results showed that the pre-pubescent children had a bias to remember adult faces, which they call the caregiver bias.
In contrast, adolescents had a bias to remember other adolescent faces, exhibiting a peer bias.
Further, among adolescents who were the same age, those who were less mature in pubertal development had better recognition memory for other similarly less mature adolescents, while those who were more mature in pubertal development had better recognition memory for peers who were similar in their level of development.
"This shows that adolescents are very clued into each other's pubertal status. They can literally see it in each other's faces, perhaps implicitly, and this influences how they keep track of each other," Ms Scherf stated.
The study, published in the journal Psychological Science, will help scientists uncover how puberty impacts the developing human brain and guide them in framing new mental health treatment.