For the first time, researchers have found the signals for “cooties” and “crushes” in the developing brain. In a new study, cognitive neuroscientists have highlighted how the brain responds to gender across a range of ages.
Led by Eva Telzer of the University of Illinois, Urbana-Champaign, the researchers found that young children had heightened brain activity in response to opposite-sex faces compared to same-sex faces, while at same time favoring members of their own sex (cooties). That gender sensitivity then wanes until adolescence and comes back in the teenage years, when teens start favoring the opposite sex (crushes).
The brain sensitivity to gender was in the amygdala, the region that processes environmental stimuli that people find emotional based on previous experience. The study, the first to look at amygdala responses to gender, was published online this month in the Journal of Cognitive Neuroscience.
The researchers scanned the brains of a sample of youth, ranging in age from 4 to 16 years old, while they viewed pictures of male and female faces displaying an emotional expression (angry, happy, or neutral). In addition to the brain scan, youth reported how many of their male versus female peers were friendly, smart, and honest (positive traits), or ugly, bad, selfish (negative traits). From these reports, Telzer’s team analyzed how children and adolescents viewed same and opposite-sex peers.
CNS spoke with Telzer about the results – including the new role for the amygdala – and their significance for how we understand gender stereotypes and childhood development.
The amygdala is not coding for threat, but is coding for motivationally important cues in the environment.
CNS: Why study the cooties effects in kids? Why is it important?
Telzer: There’s been a fair amount of work examining how social identities are processed in the brain. The majority of this work has examined one particular type of social identity – race. Developmentally, race doesn’t become an important social identity until adolescence, which we have previously shown. Earlier in development however, gender is a more salient social identity. In fact, gender stereotypes and biases develop within the first years of life, and such biases have long-lasting implications, impacting friend choices throughout childhood and adolescence (i.e., same-sex friends) as well as potential behaviors and attitudes into adulthood. Therefore, we thought it was essential to understand how “cooties” are processed in the developing brain, and how this changes from childhood to adolescence.
CNS: What were you most excited to find with your results?
Telzer: We were most excited to see that the amygdala shows heightened activation to opposite-sex peers during two developmental times – early childhood (potentially signaling “cooties”) and again during puberty (potentially signaling “crushes”). By showing these two developmental peaks in amygdala reactivity, we believe our findings have important implications for understanding the role of the amygdala. While traditional views saw the amygdala as involved in threat processing, our findings suggest that the amygdala detects stimuli of motivational relevance, a neurobiological response that signals interest and something worth paying attention to. Thus, the amygdala is not coding for threat, but is coding for motivationally important cues in the environment.
CNS: What were the major differences in gender sensitivity you found by age group?
Telzer: At the behavioral level, young children reported biases favoring their gender in-group over out-group. That is, young children reported that more of their own gender were friendly, smart, honest whereas more of the opposite gender were ugly, bad, selfish. By the teenage years, these biases favoring same-sex peers were gone. In addition, across all age groups, the overwhelming majority of youth had same-sex best friends (97.3% of participants). Therefore, even though their self-reported biases declined, such early developing biases may have long-lasting implications, as implicated in nearly all adolescents having same-sex best friends. At the neural level, we found parallel effects in the amygdala. Whereas young children (as young as 4 years old!) showed heightened amygdala activation when viewing opposite sex compared to same-sex faces, this neural bias was attenuated by adolescence. However, for those going through puberty, the amygdala showed heightened activation again to opposite sex faces.
CNS: How does your work differ from, or fit in with, past work on gender perception?
Telzer: No prior study has examined how gender is processed in the developing brain. A significant amount of behavioral studies have examined self-reported attitudes, which lay the foundation for the current research. This behavioral work has highlighted different developmental periods when gender is a more salient category. For instance, we know that early childhood is marked by strong sex stereotyping, including a bias to play with same-sex peers, the attitude that one’s own sex is better than the opposite, and the belief that the opposite sex can contaminate them (“cooties”). With development, these gender biases tend to wane, such that preteens no longer rely on these strong stereotypes. However, with puberty, gender boundaries regain salience. Our study fits in nicely with these previous findings, showing that the amygdala codes for the changing nature of gender stereotypes and biases. Thus, we have found a potential neurobiological signal for gender biases.
CNS: Why do you think the in-group favoritism was strongest with the younger children?
Telzer: Starting at a very young age, the external environment socializes children to focus on sex differences. By dressing boys and girls in either pink or blue, and by playing different games and providing different toys to boys and girls, children learn that gender must be an important category to divide the world by. As a result, children then tend to categorize their social worlds based on gender, often developing strong gender stereotypes that become rigid. Such stereotypes are reinforced during early childhood, and adults often do not temper or reduce children from being in favor of their gender in-group. Thus, young children are most likely to show in-group favoritism, a bias that will decline with age as gender becomes less salient and other identities become more important, such as racial identity.
CNS: What’s next for this work? What do you ultimately hope to accomplish?
Telzer: The next step is to simultaneously examine how multiple social identities are processed in the developing brain – gender, race, as well as social in-groups such as friends versus strangers. We hope to understand when gender versus race versus other in/out-groups may be the most motivationally relevant.
-Lisa M.P. Munoz The paper, “’The Cooties Effect’: Amygdala Reactivity to Opposite- versus Same-sex Faces Declines from Childhood to Adolescence” by Eva H. Telzer, Jessica Flannery, Kathryn L. Humphreys,Bonnie Goff, Laurel Gabard-Durman, Dylan G. Gee, and Nim Tottenham, was published online in the Journal of Cognitive Neuroscience on April 7, 2015.
