Tag Archives: developmental psychology

Developmental psychologist Charles Brainerd to receive APA award

Charles Brainerd

Charles Brainerd, professor of human development and human neuroscience, will receive the American Psychological Association’s G. Stanley Hall award for distinguished contributions to developmental science at the APA’s August 2019 meeting in San Francisco.

Regarded as the highest honor in the field of developmental psychology, the award is given to an individual or research team who has made distinguished contributions to developmental psychology in research, student training and other scholarly endeavors.

Brainerd’s research has had an impact on educational, developmental and cognitive psychology, and he is credited with major breakthroughs across his theoretical and empirical work.

“Chuck has done groundbreaking work in human memory and reasoning through experimental behavioral methods, mathematical models and neuroscience techniques,” said Qi Wang, professor of human development and department chair. “He co-developed fuzzy-trace theory of memory, judgment and decision-making that has been widely applied in the law and in medicine. His work exemplifies the best integration of theory-driven experimentation and evidence-based translational research.”

According to the APA, the award is based on the scientific merit of the individual’s work, the importance of this work for opening up new empirical or theoretical areas of developmental psychology, and the importance of the individual’s work linking developmental psychology with issues confronting society or with other disciplines.

Brainerd’s current research centers on the relationship between memory and higher reasoning abilities in children and adults, also focusing on false-memory phenomena, cognitive neuroscience, aging and neurocognitive impairment.

He has published more than 300 research articles and chapters and more than 20 books. His research covers human memory and decision-making, statistics and mathematical modeling, cognitive neuroscience, learning, intelligence, cognitive development, learning disability and child abuse.

Brainerd has been elected to the National Academy of Education; is a fellow of the Division of General Psychology, the Division of Experimental Psychology, the Division of Developmental Psychology and the Division of Educational Psychology of the American Psychological Association; and is a fellow of the American Psychological Society.

The editor of the journal Developmental Review, Brainerd has served as associate editor for journals including Child Development and The Behavioral and Brain Sciences.

Brainerd’s win of the 2019 G. Stanley Hall Award immediately follows the 2018 win of Stephen Ceci, the Helen L. Carr Professor of Developmental Psychology in the Department of Human Development.

Stephen D’Angelo is assistant director of communications at the College of Human Ecology.

The Department of Human Development welcomes 4 faculty members with research interests that include network science, social media, epigenetics, ecology, conceptual development and cultural diversity, and social cognition.

William Hobbs

William Hobbs received his doctorate in political science from the University of California at San Diego and comes to Cornell from Northeastern University where he was a postdoctoral fellow at the Network Science Institute. At Cornell, he has a joint appointment in Human Development and the Department of Government. A central feature of Hobbs' research is the use of complex relational data to study "the social effects of government policies, on how small groups of people adapt to sudden changes in their lives, and on low-dimensional representation (data that has been processed to reduce the number of random variables) of social interaction and language." [Read Dr. Hobbs' CV to learn more about his research.] One of his recent publications involved an analysis of the effect of interacting on social media networks specifically, Facebook, and longevity. [Read more about the study in a story by CBS News.]


Marlen Gonzalez

Marlen Gonzalez arrived at Cornell this summer after completing the Charleston Consortium Internship Program, a joint endeavor of the Medical University of South Carolina and the Ralph H. Johnson Veterans Affairs Medical Center. She received her doctorate from the University of Virginia (UVA), where she studied with Dr. James Coan and engaged in a truly diverse interdisciplinary research program, including, developmental psychology, neuroscience, epigenetics, evolutionary biology, and behavioral ecology. As a graduate student at UVA, Gonzalez was a LIFE Fellow from 2014-2017 which enabled her to study at UVA and at the International Max Planck Research School on the Life Course in Berlin. The central question guiding Dr. Gonzalez's research is "How do our developmental environments, and especially our social environments, shape our nervous system and biobehavioral strategies for coping in adulthood."


bethany ojalehto

Bethany ojalehto has returned to her academic roots in Human Development and the College of Human Ecology. She graduated with honors (she received the Zuckerman award for best senior thesis in HD) from Human Ecology in 2008 having majored in psychology and human rights with a certificate of African Studies and was a mentee of HD Chair, Qi Wang. Her undergraduate years were funded by a number of prestigious scholarships, including, The Nancy and Andrew Persily Scholarship, the Merrill Presidential Scholar, and the Cornell Presidential Research Scholar. Upon graduation, ojalehto received a U.S. Fulbright Research Grant to Kenya, Law and Psychology and studied cognitive development in a Kenyan refugee camp. She completed her masters and doctorate at Northwestern University under the mentorship of Drs. Douglas Medin, Sandra Waxman, and Rebecca Seligman. As a graduate student she received a Smithsonian Tropical Research Institute Short-Term Fellowship for a study of “Cultural Models and Conceptual Development in a Ngöbe Community,” Panama. She was awarded a National Science Foundation Graduate Research Fellowship for her dissertation and continued her work as a postdoctoral fellow at Northwestern. According to ojalehto, her research "explores how people conceptualize agency and ecologies, with a focus on cultural variation in social cognition and human-nature relationships." [Read more about Dr. ojalehto's research and outreach at website: http://sites.northwestern.edu/ojalehto/ and watch her presentation at the National Academy of Sciences Arthur M. Sackler Colloquium, Pressing Questions in the Study of Psychological and Behavioral Diversity].


Lin Bian

Lin Bian will join the Department of Human Development in January 2019 as the Evalyn Edwards Milman Assistant Professor. She is currently completing a postdoctoral fellowship with Dr. Ellen Markman at Stanford University. Dr. Bian received her doctorate in developmental psychology from the University of Illinois at Urbana-Champaign in 2017 under the mentorship of Drs. Andrei Cimpian and Renée Baillargeon. Her research examines the development of social cognition, with an emphasis on children’s reasoning about social groups. In this vein, she has pursued two major lines of research: One line of work focuses on the acquisition and consequences of stereo- types about social groups for children’s interests and motivation. The other line of work focuses on infants’ and toddlers’ sociomoral expectations, especially as how they apply to behaviors within vs. across group boundaries. [Watch the NBC News video about Dr. Bian's research, Psychologist Breaks Ground with Gender Bias Study].

 

Reprinted from The Cornell Chronicle, September 14, 2017.

by Stephen D'Angelo

Stephen Ceci

Stephen Ceci, the Helen L. Carr Professor of Developmental Psychology in the Department of Human Development, will receive the American Psychological Associations’ G. Stanley Hall award for distinguished contributions to developmental science at APA’s August 2018 meeting in San Francisco.

The highest honor in the field of developmental psychology, the award is given to an individual or research team who has made distinguished contributions to developmental psychology in research, student training and other scholarly endeavors.

“Steve has made seminal contributions to the basic scientific research of the developing mind in young children and to the critical translation of research findings to real-life settings,” said Qi Wang, professor of human development and department chair. “His work best exemplifies the integrative approaches that we take in the use of scientific theories and methods to vigorously study real-world problems in diverse populations.”

The award is based on the scientific merit of the individual’s work, the importance of this work for opening up new empirical or theoretical areas of developmental psychology, and the importance of the individual’s work in linking developmental psychology with issues confronting society or with other disciplines.

Ceci has written approximately 450 articles, books, commentaries, reviews and chapters. He has served on the advisory board of the National Science Foundation for seven years and was a member of the National Academy of Sciences’ Board of Behavioral and Sensory Sciences. He is past president of the Society for General Psychology, serves on 11 editorial boards, including Scientific American Mind, and is senior adviser to several journals.

Ceci’s honors include the American Academy of Forensic Psychology’s Lifetime Distinguished Contribution Award (2000), the American Psychological Association’s Division of Developmental Psychology’s Lifetime Award for Science and Society (2002), the Distinguished Scientific Contribution Award for the Application of Psychology (2003), the Association for Psychological Science’s James McKeen Cattell Award (2005), the Society for Research in Child Development’s lifetime distinguished contribution award (2013) and the American Psychological Association’s E.L. Thorndike Award for lifetime contribution to empirical and theoretical psychology (2015).

Stephen D’Angelo is assistant director of communications at the College of Human Ecology.

The Cornell Chronicle, August 1, 2017.

By Stephen D'Angelo

Cornell researchers are working with Head Start Centers and day schools in New York City on early-intervention work to promote development of spatial skills and language acquisition in preschoolers.

Marianella Casasola

Marianella Casasola, associate professor of human development and a faculty fellow of the Bronfenbrenner Center for Translational Research in Cornell’s College of Human Ecology, said studies show those with better spatial skills are more likely to flourish in STEM fields.

“Working with children at Head Start in Harlem and through a partnership with the Audrey Johnson Day Care Learning Center in Brooklyn allows us to focus on families from a variety of demographics and backgrounds, and to target research on environmental factors within populations of various socioeconomic status,” Casasola said.

Casasola is examining the benefits of constructive play – using blocks, puzzles and shapes – and how language through narration of activities affects cognitive development and spatial skills. She hopes her research findings will inform early-education programs and lead to creation of ideal environments to develop children’s cognitive skills, no matter their demographic background.

“Our goal is to not only understand how early spatial and language skills develop, but also how best to promote their development both at home and in the classroom,” she said. “Designed for preschoolers from low-income families, these programs would be constructed to establish environments for the early development of these skills and promote parent interaction within day-to-day activities, such as counting, simple math and reading.”

Casasola and her team of students are collaborating with the Clinical and Translational Science Center at Weill Cornell Medicine to discover effective approaches to translate such findings for families. She and her students design and host monthly parent training workshops at Brooklyn’s Audrey Johnson day school.

“Children who both interacted and were narrated to saw at least a 30 percent increase in spatial gains over the group that still interacted with the same sorts of activities and games, but did not have language incorporated into their play by an adult,” she said. “Both groups improved, but those who heard items being labeled and actions described showed significantly greater gains.”

The hope is to integrate such development practices into the busyness of day-to-day life and positively impact a child’s language and learning development.

“Many people are surprised to hear that talking to infants really matters,” Casasola said. “The simple message is, remember to talk to your child. And have fun even for only a few minutes of play.”

Amelia Hritz, the first student in Human Development's Dual PhD and JD Program in Developmental Psychology and Law, was featured in a recent post reprinted from the Cornell Law School website, May 17, 2017.

Amelia Hritz

Two weeks before its 2017 convocation, Cornell Law School celebrated twenty-two, soon-to-be graduates who received coveted judicial clerkships. The celebration included a champagne toast by faculty, alumni, and staff at Myron Taylor Hall.

The event was the first of its kind to highlight the growing number of graduates who clerk for judges at all levels of the state and federal court systems across the country. The future clerks were honored by Eduardo Peñalver, the Allan R. Tessler Dean and Professor of Law; John Blume, the Samuel F. Leibowitz Professor of Trial Techniques; and Judge Richard Wesley ’74 of the U.S. Court of Appeals for the Second Circuit.

"Over the last decade, we've definitely seen an increase in the number of clerkships for each graduating class," said Elizabeth Peck, assistant dean for professional development and clerkships. "Clerkships have become a much greater priority for our institution."

One way the Law School has made a stronger commitment to clerkships was by creating a new position for Peck to help current law students and recent graduates land clerking positions. The Clerkship Celebration, held on April 26, is another way the law school is highlighting the value of clerkships.

"Securing a judicial clerkship is a 'capstone event' based on years of hard work and academic excellence, both before our students arrive at Cornell and during their time here with us, high above Cayuga's waters," Blume, chair of the faculty clerkship committee, said at the event.

Amelia Courtney Hritz, ’17, who is working on a Ph.D. in Cornell's joint program in developmental psychology and law, was one of the graduates honored at the celebration. She will clerk for Judge Peter Hall ’77 of the U.S. Court of Appeals for the Second Circuit for a one-year term beginning in 2019.

"I'm excited to learn more about how judges think by observing what types of legal arguments are persuasive to Judge Hall," Hritz said. "I think that by clerking I will gain a different perspective and become a better lawyer."

Hritz, former editor in chief of the Cornell Law Review, said she became interested in the Second Circuit when the Law Review published a special volume containing biographies of all the judges who served on the court for its 125th anniversary last year. She decided to pursue clerking while taking the class, Federal Appellate Practice, which Wesley and Blume co-taught last fall.

Peck, a former clerk herself, said clerking for a judge allows graduates to sharpen their skills in a number of areas, including legal research and writing. "It also provides clerks with a lifelong mentor and great networking opportunities," she said. "It's the kind of credential that will be valuable for the rest of their careers."

Published on Apr 24, 2017

Gay youth today describe themselves as proud, happy, and grateful – something many of us would have found surprising a generation ago. Yet many adults seem skeptical about this change in perceptions and attitudes. What does it mean to be gay today? Professor Ritch Savin-Williams, professor emeritus of developmental psychology in the Cornell College of Human Ecology, observes that huge gaps still remain in our knowledge about gay youth’s basic developmental needs, their sexual and romantic life, and overall well-being. With his new book, Becoming Who I Am: Young Men on Being Gay, Savin-Williams aims to begin filling this void, exploring identity and sexuality as told by today’s generation of gay young men. Through a series of in-depth interviews with teenagers and men in their early 20s, he offers a contemporary perspective on gay lives in present day America. In a Chats in the Stacks book talk at Mann Library in March 2017, Dr. Savin-Williams shared highlights from this work and some thoughts about what his findings suggest for the future of gay youth in an age of growing tolerance.

 whitlock460Online course brings self-injury to the surface                                                                     Janis Whitlock, Ph.D. ’03, director of the Cornell Research Program on Self-Injury and Recovery (CRPSIR) and a research scientist in the Bronfenbrenner Center for Translational Research, hopes to spotlight the issue by launching a set of web-based                                   education and training courses.
sad girlEarly puberty in girls raises the risk of depression                                                                   Perri Klass interviewed Jane Mendle in her NY Times' column, The Checkup, about Mendle's research with girls who begin puberty earlier than their peers. Read here about her findings and the risks these girls face in adolescence. 
LRDM lab members and 4-H Career Explorations studentsLearning to reduce risky behaviors leads to STEM careers                                                          The Laboratory for Rational Decision Making, led by Dr. Valerie Reyna in Human Development, welcomed 24 high school students from 18 different counties in New York State as part of  the 4-H Career Explorations Conference.
gsalogoGerontological Society selects experts on aging as fellows                     Professors Corinna Loeckenhoff and Elaine Wethington of human development, were two of 94 professionals named on May 31 to the society, which is the largest of its kind seeking to understand aging in the United States.

Students in the News

Sarah MooreHD graduate student in the news: Sarah R. Moore                                                             Sarah R. Moore, Ph.D. student of Dr. Richard A. Depue, was awarded the Early Career Outstanding Paper Award in Developmental Psychology. Read her summary of research on how people differ in their interaction with their environment.
MorenoMarcos Moreno '17 is named a 2016 Udall scholar                                                                  The Udall Scholarship supports undergraduates with excellent academic records and who show potential for careers in environmental public policy, health care and tribal public policy. Moreno is a human development major concentrating in neuroscience in                               the College of Human Ecology.
tumblr_inline_oab7iaDzqM1tqatqb_1280Summer Scholar Spotlight: Deborah Seok ‘17                                                                              In faculty research labs, in communities across the state, and at jobs and internships around the globe, Human Ecology undergrads are making a powerful impact this summer as they apply their knowledge and skills in real-world settings.

 Articles on the Web

Robert SternbergHow can current research inform the development of new methods to assess intelligence?                                                                                                                                    Read the fifth post from the six-part series, "Researching Human Intelligence" on fifteeneightyfour, the blog of Cambridge University Press, with Robert Sternberg,                                           professor of human development.

 Multimedia

video play buttonVideo introduces the Program for Research on Youth Development and Engagement (PRYDE), explaining it's mission and introducing key researchers and practitioners involved in the project.                                                                                                                                             
video play button                                                                                                                                                                    Professor Anthony Burrow Discusses Youth and Purpose with Karl Pillemer, Director of BCTR 

 

Ong & Loeckenhoff New book probes emotion, aging and health                                                                         New approaches to understanding physical and psychological changes in old age – differences in personality, for instance, or responses to stressful events and the role of positive emotions in promoting well-being – are presented in a new book co-edited                                       by Cornell human development professors Anthony Ong  and Corinna Loeckenhoff.                   
QiWangTNRetweeting may overload your brain                                                                                               In a digital world where information is at your fingertips, be prepared to hold on tight before it slips right through them. Research at Cornell and Beijing University finds retweeting or otherwise sharing information creates a “cognitive overload” that                                           interferes with learning and retaining what you’ve just seen.
bebesInside Cornell’s BABY Labs                                                                                                            Steven S. Robertson and Marianella Casasola, professors in Human Development, run baby labs at Cornell. where researchers are discovering more about the nuances of infant development. It’s a crucial area of academic research and exploration, given the                               impact early development has on later stages of life.
 20120827_rns74_portrait_25Mapping the Resting-state Brain                                                                                                         In the Department of Human Development, fMRI (functional magnetic resonance imaging) informs Nathan Spreng’s studies of large-scale brain network dynamics and their role in cognition.
BaileyPSPIimage-200x300 Checking Up on the Science of Homosexuality                                                                               A new systematic review and commentary published in the journal Psychological Science in the Public Interest takes a sweeping look at what the evidence says about homosexuality and sexual orientation in general. 

Student in the News

 Human Ecology Faculty-Led Undergraduate Research. Eve DeRosa / Annie EricksonSide by side                                                                                                                                       Many undergraduates in Human Development work side by side with faculty in the lab. Read about this transformative approach to learning in an interview with Annie Erickson '16 and her mentor, Professor Eve De Rosa.

 More Stories

K.KinzlerStudies Suggest Multilingual Exposure Boosts Children's Communication Skills      Listen to NPR's Robert Siegel's interview with Katherine Kinzler, associate professor of psychology and human development, about her research on the development of social skills in monolingual and multilingual children.                                                                                 

Multimedia

video play button                                                                                                                                                          Professor Corinna Loeckenhoff talks about aging with Karl Pillemer, Director of the BCTR

 

Reprinted from Research Cornell News
by Alexandra Chang

An 18-month-old boy sits on his father’s lap in a small room furnished with a child-sized chair and a short table. The boy faces a monitor. On it, a video starts to play. A woman, Psychology graduate student Kate Brunick, assembles a simple toy—she holds two bright green cups, places a plastic object inside one, brings the cups together, and closes them to form a capsule. She shakes it; it’s a makeshift rattle.

As the boy watches the video, Michael H. Goldstein, Psychology, and his graduate students observe from the B.A.B.Y. (Behavioral Analysis of Beginning Years) lab’s observation room, a space hidden behind one-way glass and filled with monitors and video controls. Once the recording is done, Psychology graduate student Melissa Elston heads into the room where the boy and father sit. She’s carrying the toy from the video clip and places it on top of the table in front of the boy.

The boy doesn’t budge. After a couple minutes of encouragement from Elston, it’s clear he’s not assembling a rattle on this visit. It’s not a failure. This is exactly what Goldstein expects.

The study is just one of the many taking place at Cornell’s infant labs, where researchers are discovering more about the nuances of infant development. It’s a crucial area of academic research and exploration, given the impact early development has on later stages of life.

How Babies Learn in Social Settings

This particular study is on a phenomenon called the "video deficit effect," in which babies from 12 to 30 months are much worse at learning from video presentations than from real-life experiences. The group studies the babies in three scenarios: one in which babies see a live presentation of putting the toy together, another with an automatic pre-recorded video, and a third in which the baby has to press a button in order to play the pre-recorded video. Their theory is that the first group will learn, the second won’t, and the third will because the experience is contingent on and immediately follows their own action.

The study falls under the lab’s research on how babies learn in social context. Most of the work Goldstein and his codirector, Jennifer Schwade, do is on how social interactions affect the acquisition of speech and language in both babies and songbirds (in their case, song). Contingency, they’ve found, is crucial to learning.

Goldstein argues that the social behavior of adults contains patterns that can guide young learners. “If you want to understand how infants learn, you’ve got to understand not only what’s in the baby’s head but what social environment the baby’s head is in,” he says.

Alongside Goldstein, Steven S. Robertson and Marianella Casasola, Human Development, run baby labs at Cornell.

How Babies Collect Information from Their Environment through Visual Foraging

Steve S. Roberston, Professor in Human Development

If, when you think of an infant lab, you imagine a baby outfitted with sensors, you’re on the right track when it comes to Robertson’s research. He examines mind–body relations in very young babies, typically three-month-olds. Specifically, he looks at the relationships between vision, motor activity, and attention during visual foraging, a major way in which infants gather information from their surroundings.

“If you want to understand how infants learn, you’ve got to understand not only what’s in the baby’s head but what social environment the baby’s head is in,” Goldstein says.

To study the dynamics of visual foraging, Robertson depends on EEG measurements and a few flashing rubber ducks. When a baby arrives at the lab, she is placed in a high chair in front of three yellow rubber ducks. The ducks are outfitted with LED lights and attached to motor-controlled rods that can move them right and left. Atop the baby’s head is an EEG cap. It measures the oscillations in the activity of visual neurons. Each duck’s light flashes at a different frequency and the baby’s oscillations in neural activity will match the frequency of the duck receiving her attention.

Through these measurements, Robertson knows when a baby is paying attention to a certain duck. A video camera records the baby, so they can see how her eyes move in relation to that attention. What Robertson found and reported in a study published in the Proceedings of the National Academy of Sciences in 2012 is that attention is not always directly correlated to gaze. In fact, babies redirect their attention to a new duck ahead of actually looking at it. What’s more surprising is that a second or two before shifting to the new duck, babies actually paid more attention to the duck they didn’t choose to look at.

Robertson sees this behavior as consistent with the inhibition of return (IOR) observed in adults. In IOR, attention is suppressed toward previously inspected areas or objects in favor of new locations or objects. It would make sense for a baby to look at, and focus attention toward, a duck that it had not been paying attention to earlier.

Robertson is currently conducting further studies to test whether the behavior in infants truly is the development of IOR. “The adaptive value of this in visual exploration is that it keeps you from going to the same spot,” Robertson says. “You get to literally explore new locations in your environment and pick up new information.” And he adds that it’s especially important to study in infants because “the nature of visual input during this period has important consequences for the structural and functional development of the brain,” which happens quickly in early infancy.

Understanding Spatial Language Skills

20130506_casasola_portrait_48

Marianella Casasola, Proessor in Human Development

Casasola agrees that looking at babies is crucial for tracing how certain skills develop. One of her main interests is in understanding the link between spatial cognition and the acquisition of spatial language—language relating to space, location, and shapes.

Spatial awareness is a core cognitive ability. It is linked to achievement in math and sciences and has broader implications for everyday life. For example, spatial cognition relates to our ability to navigate, to project how objects will look from different angles, and even to reading orientation. Casasola wants to understand how these skills develop, but she also aims to figure out how they relate to acquisition of spatial language and what sorts of experiences promote spatial skills.

For this area of research, Casasola studies a wide age range, from babies at 14 months up to toddlers at 4.5 years old. The studies vary from age to age. For example, younger babies watch a computer animation of two halves of a shape—say, a heart—on either side of a curtain. The two halves move together and then disappear behind the curtain. The curtain then lifts and shows the whole heart. Or, it could show a completely different shape, like a square. Casasola relies on infant looking time to determine how they perceive these expected and unexpected shapes.

Older children are asked to put halves of foam shapes together. Casasola has also done naturalistic studies, during which researchers play with kids using spatial toys—puzzles, origami, and Legos. One group receives a lot of spatial language: “Fold the paper horizontally, you’ve made a triangle.” The other group receives general language, like “do this, now fold it like this, look what you’ve made.” What Casasola’s research found is that children with more exposure to spatial language are much better at naming shapes. The more spatial language a child acquires, the better they are at accomplishing nonverbal spatial tasks. Throughout the studies of spatial learning, Casasola wants to determine at what ages significant advances can be made.

“No one has looked at trajectory, which is important,” she says. “It can answer questions like, how stable are spatial skills? It can also highlight when might be ultimate time periods to promote it.” Knowing this will be useful for effective interventions that nurture better spatial cognition to help babies and children develop better spatial cognition abilities.

Using the Research

Goldstein is already on his way to applying his research findings to real-world intervention. Cornell’s Bronfenbrenner Center for Translational Research has recently funded the B.A.B.Y. Lab’s pilot intervention program to aid infant language development in low socioeconomic status families.

In previous research, the lab found that the timing and the form of reactions to infant babbling are crucial for language development. For example, if a baby is babbling at a toy, it’s important to respond immediately and to engage with that toy. The baby then sees there’s a reward to vocalizing and takes the next learning step.

The work done in the infant labs has a direct public impact. “Outreach is the real key,” Goldstein says. “We’re doing work that should improve the lives of parents and infants.”

Reprinted from Evidence-based Living, a project of the Bronfenbrenner Center for Translational Research.

Diversity in sexual orientation—whether gay, straight, bisexual, or somewhere in between—has sparked long-standing controversies across the globe. In the United States, recent debates have centered around the civil rights for same-sex couples. In many other countries, homosexuality is considered illegal; in some, it’s punishable by death.

Often, these social and political debates refer to the “science of homosexuality” —or what we really know about why individuals are attracted to particular sexes. If you’ve followed these debates, you’ve likely heard people refer to the idea that homosexuality is genetic, or that it is a choice people make. But what does science really tell us about sexual orientation?

A new systematic review and commentary published in the journal Psychological Science in the Public Interest takes a sweeping look at what the evidence says about homosexuality and sexual orientation in general. While the articles draw some conclusions about the causes and connections that lead to different sexual orientations, they also point out what we don’t know about homosexuality.

Here’s what we do know:

  • Across research papers, somewhere between 2 and 11 percent on people report experiencing same-sex attractions. The exact number varies depending on how the question is asked and how the research paper categorizes homosexuality.
  • Children who do not conform to gender identities—for example, boys who wear dresses or girls who act as “tomboys”—are more likely to identify as not heterosexual later in life. This applies to cultures across the globe, no matter what their gender roles.
  • Political attitudes about sexual orientation are connected to people’s understanding of the causes of same-sex behavior. People who believe that homosexuality is immoral tend to believe that sexuality is a choice or is influenced by social factors. Those who support free expression of sexuality tend to believe there are biological factors that influence sexual orientation.
Ritch Savin-Williams

Ritch Savin-Williams, Professor in Human Development

In a commentary published with the systematic review, Cornell Human Development Professor Ritch Savin-Williams offers evidence of a continuum of sexual orientation that includes a wide variety of classifications, including people who are “mostly straight” with a small degree of same-sex attraction or people who are “mostly gay or lesbian” with some attraction to opposite-sex partners. Taking into account these groups, the prevalence of people experiencing at least some same-sex feelings may be much broader than is represented in many studies.

“Traditionally, we’ve thought of sexual orientation in terms of three categories: you are or identify as straight, bisexual, or gay/lesbian,” he explained. “But recent research from a different perspective strongly suggests that this view mischaracterizes a significant number of people who have varying degrees of opposite-sex and same-sex romantic and sexual attractions and the ratio might well vary across contexts and time. That is, rather than categories there is a spectrum of sexualities and the in between points along a continuum constitute perhaps a quarter of all individuals, especially if you consider their infatuations, crushes and romantic feelings. Recognizing this reality has the potential to subvert any us-versus-them perspective, thus promoting the sexual and romantic commonality we have with each other.”

What the data do not tell us definitively is the why people have different sexual orientations. But there is evidence that there are multiple contributing factors, some of which we don’t yet understand.

The most scientifically plausible theories, according to the review, propose that sexual orientation is a product of biology and social factors, to varying degrees for different people.

For example, there is credible evidence across cultures that, for men, their birth order has some effect on their sexual orientation. Men with more older brothers are significantly more likely to identify as gay compared with first-born sons or men with older sisters. This is likely related to evidence that prenatal hormones affect the sexual orientation of boys. There is also clear evidence that specific genetic profiles contribute to sexual orientation, but likely interact with other factors.

What’s the take-home message here? There is a lot we don’t yet understand about how individuals develop their gender identity and sexual orientation. But it is absolutely clear that there are a wide variety of factors—both biological and social—that play into each person’s sexual identity.