Screams of 'joy' sound like 'fear' when heard out of context

"Our work intertwines language and non-verbal communication in ways that haven't been done in the past," says Emory psychologist Harold Gouzoules, senior author of the study.

By Carol Clark

People are adept at discerning most of the different emotions that underlie screams, such as anger, frustration, pain, surprise or fear, finds a new study by psychologists at Emory University. Screams of happiness, however, are more often interpreted as fear when heard without any additional context, the results show. 

PeerJ published the research, the first in-depth look at the human ability to decode the range of emotions tied to the acoustic cues of screams. 

“To a large extent, the study participants were quite good at judging the original context of a scream, simply by listening to it through headphones without any visual cues,” says Harold Gouzoules, Emory professor of psychology and senior author of the study. “But when participants listened to screams of excited happiness they tended to judge the emotion as fear. That’s an interesting, surprising finding.” 

First author of the study is Jonathan Engelberg, an Emory Ph.D. student of psychology. Emory alum Jay Schwartz, who is now on the faculty of Western Oregon University, is co-author. 

The acoustic features that seem to communicate fear are also present in excited, happy screams, the researchers note. “In fact, people pay good money to ride roller coasters, where their screams no doubt reflect a blend of those two emotions,” Gouzoules says. 

He adds that the bias towards interpreting both of these categories as fear likely has deep, evolutionary roots. 

“The first animal screams were probably in response to an attack by a predator,” he says. “In some cases, a sudden, loud high-pitched sound might startle a predator and allow the prey to escape. It’s an essential, core response. So mistaking a happy scream for a fearful one could be an ancestral carryover bias. If it’s a close call, you’re going to err on the side of fear.” 

The findings may even provide a clue to the age-old question of why young children often scream while playing. 

“Nobody has really studied why young children tend to scream frequently, even when they are happily playing, but every parent knows that they do,” Gouzoules says. “It’s a fascinating phenomenon.” 

While screams can convey strong emotions, they are not ideal as individual identifiers, since they lack the more distinctive and consistent acoustic parameters of an individual’s speaking voice. 

“It’s just speculative, but it may be that when children scream with excitement as they play, it serves the evolutionary role of familiarizing a parent to the unique sound of their screams,” Gouzoules says. “The more you hear your child scream in a safe, happy context, the better able you are to identify a scream as belonging to your child, so you will know to respond when you hear it.” 

Gouzoules first began researching the screams of non-human primates, decades ago. Most animals scream only in response to a predator, although some monkeys and apes also use screams to recruit support when they are in a fight with other group members. “Their kin and friends will come to help, even if some distance away, when they can recognize the vocalizer,” he says. 

In more recent years, Gouzoules has turned to researching human screams, which occur in a much broader context than those of animals. His lab has collected screams from Hollywood movies, TV shows and YouTube videos. They include classic performances by “scream queens” like Jaime Lee Curtis, along with the screams of non-actors reacting to actual events, such as a woman shrieking in fear as aftershocks from a meteor that exploded over Russia shake a building, or a little girl’s squeal of delight as she opens a Christmas present. 

In previous work, the lab has quantified tone, pitch and frequency for screams from a range of emotions: Anger, frustration, pain, surprise, fear and happiness. 

For the current paper, the researchers wanted to test the ability of listeners to decode the emotion underlying a scream, based solely on its sound. A total of 182 participants listened through headphones to 30 screams from movies that were associated with one of the six emotions. All of the screams were presented six times, although never in sequence. After hearing a scream, the listeners rated how likely it was associated with each of six of the emotions, on a scale of one to five. 

The results showed that the participants most often matched a scream to its correct emotional context, except in the case of screams of happiness, which participants more often rated highly for fear. 

“Our work intertwines language and non-verbal communication in a way that hasn’t been done in the past,” Gouzoules says. 

Some aspects of non-verbal vocal communication are thought to be precursors for language. The researchers hypothesize that it may be that the cognitive underpinnings for language also built human capacity in the non-verbal domain. “It’s probably language that gives us this ability to take a non-verbal vocalization and discern a wide range of meanings, depending on the acoustic cues,” Gouzoules says.

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Heritable traits that appear in teen years raise risk for adult cannabis use

Some of the risk for repeated cannabis use into adulthood can be attributed to the genetic effects of neuroticism, risk tolerance and depression, the study found. "While this work marks an important step in identifying genetic factors that can increase the risk for cannabis use, a substantial portion of the factors that raise the risk remain unexplained," says Emory psychologist Rohan Palmer.

By Carol Clark

While some youth experiment with marijuana but don’t go on to long-term use, others develop a problematic pot habit that continues into adulthood. A major new analysis shows that at least a small portion of the risk for developing into an adult marijuana user may be related to inherited behaviors and traits that appear during adolescence. 

The journal Addiction published the findings by researchers at Emory and Brown University. 

“Our analysis suggests that some early adolescent behaviors and traits — like depression, neuroticism and acting out — can be indicative for cannabis use later in life,” says Rohan Palmer, senior author of the paper and assistant professor in Emory’s Department of Psychology, where he heads the Behavioral Genetics of Addiction Laboratory. 

“Decades of research has shown that behaviors can have a genetic component,” adds Leslie Brick, lead author and assistant professor in the Department of Psychiatry and Human Behavior in Brown’s Alpert Medical School. “And while there is not one genetically-influenced trait that determines whether you’re going to be a long-term cannabis user, our paper indicates that there are polygenic effects across multiple inherited behaviors and traits that show a propensity for increased risk.” 

Brick, a long-time collaborator with Palmer, also holds an adjunct faculty appointment in Emory’s Department of Psychology. 

The Transmissible Liability Index is a well-known measure for a constellation of heritable traits that may appear during the developmental years that are associated with the risk of a substance use disorder. For the current paper, the researchers wanted to tease out which of these heritable characteristics might be associated with repeated marijuana use later in life. 

“Cannabis use has been less studied than tobacco and alcohol,” Palmer says. “For one thing, it’s harder to get people to answer detailed questionnaires honestly about cannabis, since it’s an illegal substance. And it’s also much more difficult to standardize the amount of cannabis consumed, as compared to cigarettes and liquor.” 

Cannabis use, however, is widespread among adolescents and young adults. In 2018, more than 35 percent of high school seniors surveyed reported having used marijuana during the past year and more than 20 percent reported doing so during the past month, according to the National Institute on Drug Abuse (NIDA). 

As cultural norms have shifted, including the legalization of marijuana for adult recreational use in many states, teens’ perceptions of the risks of marijuana use have declined. 

Those risks, however, are real. 

“Adolescence is a major period of brain development,” Brick says. “In fact, our brains don’t stop developing until we are around 25 years old. Research indicates that cannabis has some major impacts on our biology, although its full effects are still not well understood.” 

The researchers drew data from the National Longitudinal Study of Adolescent Health, or Add Health, which includes a nationally representative sample of 20,000 adolescents in grades 7 to 12 in the United States who have been followed into adulthood. Comprehensive data from early adolescence to adulthood was collected on health and health-related behavior, including substance use, personality and genetics. 

For the current paper, the researchers identified a large homogenous subgroup of individuals from the Add Health study, about 5,000 individuals of European ancestry, for their final analytic sample. They then leveraged existing genome-wide association studies to examine whether certain heritable behavioral traits noted during adolescence were associated with the Transmissible Liability Index, and whether any of these traits were also associated with risk for later cannabis use. 

The results showed that a small portion of the risk for repeated cannabis use into adulthood can be attributed to the genetic effects of neuroticism, risk tolerance and depression that can appear during adolescence. 

“While this work marks an important step in identifying genetic factors that can increase the risk for cannabis use, a substantial portion of factors that raise the risk remain unexplained,” Palmer says. “We’ve shown how you can use existing data to assess the utility of a polygenic risk score. More studies are needed to continue to identify unique genetic and other environmental sources for the risk of long-term, problematic use of cannabis.” 

“Better understanding of what behaviors and traits may give someone a pre-disposition for long-term cannabis use gives us a better shot of identifying those most at risk so we can home in on effective interventions,” Brick says. 

A major limitation of the current study, the researchers add, is that it focused on individuals of European ancestry, because no sample size large enough for the genome-wide analysis was available for other ancestral groups. 

Co-authors of the study include the following members of Emory’s Behavioral Genetics of Addiction Laboratory: Graduate students Lauren Bertin, Kathleen Martin and former undergraduate Victoria Risner (now an Emory alum); and Chelsie Benca-Bachman, associate director of research projects in the lab. 

The work was supported by an Avenir grant from the National Institute on Drug Abuse.

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Water temperature key to schistosomiasis risk and prevention strategies

Karena Nguyen, a post-doctoral fellow in Emory's Department of Biology, shown with two of the freshwater snails that serve as intermediate hosts for the parasites that cause schistosomiasis. (Photo by Rachel Hartman)

By Carol Clark

About one billion people worldwide are at risk for schistosomiasis — a debilitating disease caused by parasitic worms that live in fresh water and in intermediate snail hosts. A new study finds that the transmission risk for schistosomiasis peaks when water warms to 21.7 degrees centigrade, and that the most effective interventions should include snail removal measures implemented when the temperature is below that risk threshold. 

The Proceedings of the National Academy of Sciences published the results, led by Emory University, the University of South Florida and the University of Florida. 

“We’ve shown how and why temperature matters when it comes to schistosomiasis transmission risk,” says Karena Nguyen, a post-doctoral fellow in Emory University’s Department of Biology and a first author of the study. “If we really want to maximize human health outcomes, we need to consider disease transmission in the context of regional temperatures and other environmental factors when developing intervention strategies.” 

The findings indicate that climate change will increase schistosomiasis risk in regions where surface water moves closer to 21.7 degrees centigrade, or 71 degrees Fahrenheit. The researchers also found, however, that implementing snail control measures decreases transmission but raises the temperature for peak transmission risk to 23 degrees centigrade, or 73 degrees Fahrenheit. 

Co-first author of the paper is Philipp Boersch-Supan, an expert in ecological systems at the University of Florida and the British Trust for Ornithology. 

Nguyen is a member of the lab of David Civitello, Emory assistant professor of biology and a co-author of the PNAS paper. The Civitello lab studies the ecological dynamics of disease, aquatics and agricultural ecology through a combination of experiments, field surveys and models. 

“The control of schistosomiasis currently relies on treating infected people,” Civitello says. “However, there is renewed awareness that the ecological factors surrounding the disease also need to be considered. Our paper is a beautiful example of the potential power of uniting ecology with human disease interventions and control measures.” 

Click on graphic of the life cycle of the schistosomiasis parasite, above, to enlarge.

Schistosomiasis is one of the most devasting water-based diseases in developing countries, with more than 200 million people infected worldwide, leading to around 200,000 deaths annually. It is caused by Schistosoma parasites that have a complex life cycle. Freshwater becomes contaminated by the parasite’s eggs when infected people urinate or defecate in the water. After the eggs hatch, the parasites enter freshwater snails where they develop and multiply. More mature parasites are able to leave the snails and re-enter the water. These free-swimming parasites can then burrow into the skin of people who are wading, swimming, bathing, washing or doing agricultural work in contaminated water.

Children who are repeatedly infected can develop anemia, malnutrition and learning difficulties. Over the long term, the parasites can also damage the liver, intestine, lungs and bladder. 

“Schistosomiasis is treatable — people can take a drug to get rid of the adult parasites in their bodies,” Nguyen says. “But in areas where schistosomiasis is prevalent, people can easily get reinfected by coming in contact with contaminated water. And children, who like to play in water, tend to have the highest burden of the disease.” 

For the current paper, Nguyen focused on how global climate change and rising water temperatures might affect each stage of the schistosomiasis transmission cycle. It was already established that both the parasites and the snails are sensitive to water temperature, with each stage having an optimum temperature. 

“I wanted to build on previous work to see if we could use it to find better predictors for human risk and more effective interventions,” Nguyen says. 

The researchers integrated an epidemiological model of schistosomiasis and temperature-dependent traits of the parasites and their snail hosts to run different computer-simulated interventions. The results showed that interventions targeting snails were most effective at reducing transmission, and pinpointed the water temperature for when the risk of transmission peaks. 

Unexpectedly, the simulations also showed that interventions targeting snail removal actually raised the peak transmission temperature by 1.3 degrees centigrade, while reducing transmission risk. 

“That may not sound like a lot,” Nguyen says, “but we’re talking about water temperature, which takes a lot of energy to warm, so 1.3 degrees is actually a big shift.” 

Snails naturally start to die off at higher water temperatures. The data in the new paper shows how implementing snail control measures, such as through chemical treatment of the water, amplifies snail mortality at all temperatures. This lowers transmission risk overall, but allows peak transmission risk to occur at higher temperatures. 

These insights can guide public health workers to time their interventions, by factoring in regional water temperatures, and how the temperatures fluctuate during different seasons of the year. 

“Our findings don’t mean that we should stop human treatment for schistosomiasis,” Nguyen says. “Instead, it will likely be beneficial to include both the human and ecological components. By combining human drug treatment with snail removal measures, during times when water is below the peak transmission temperature, we may be able to maximize the efficacy of an intervention.” 

Additional authors of the PNAS paper include Jason Rohr (University of Notre Dame), Valerie Harwood (University of South Florida), Rachel Hartman (Emory staff) and Emory graduate student Sandra Mendiola. 

The work was funded by the National Institutes of Health, the National Science Foundation, the Porter Foundation and the U.S. Department of Agriculture.

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Atlanta Science Festival: Life is looking up with science!

This year's festival is a hybrid of more than 80 events, including virtual activities and those held in the outdoors.

By Carol Clark

The Atlanta Science Festival returns March 13-27 stronger than ever. This year’s hybrid of more than 80 events includes virtual activities and those held in safe, socially-distanced environments, aimed to educate, engage and entertain all ages. 

The 2021 festival theme — “Science Always Prevails!” — celebrates the metro area as a powerhouse of scientific research, scholarship, service and innovation, from battling the COVID-19 pandemic to protecting the unique natural resources of Georgia. 

“The pandemic has heightened public awareness of the value of science,” says Meisa Salaita, executive co-director of Science ATL, the non-profit organization that produces the Atlanta Science Festival. “All of our partners, including Emory, have come together to keep the festival going strong, despite the challenges. Everyone is inspired by the knowledge that our mission of service to the community is more important than ever.” 

The Atlanta Science Festival, now in its eighth year, was co-founded by Emory, Georgia Tech and the Metro Atlanta Chamber. 

“We’ll not only continue our celebration of science,” says executive co-director Jordan Rose, “but use it as an opportunity to share knowledge that inspires and empowers others to make the world a better place.” 

Bringing more science to more people

On Friday, March 12, one day before the festival launch, an event called “Imagining the Future” will help set the tone. Local STEM professionals, including many Emory faculty and students, will participate in virtual visits to 100 metro Atlanta K-12 classrooms to give students a sense of how science is done, talk about some major questions that remain unanswered in science, and inspire students to imagine themselves shaping the future as STEM-literate professionals of tomorrow. 

“One of the benefits of having virtual events is that we are able to bring more science, and more science-learning opportunities, to more people,” Salaita says. 

Some of this year’s festival highlights include: 

• “Atlanta 40,” a celebration of 40 notable organisms of the region explained by videos created by experts and luminaries and mini conservation challenges that the public can complete. 
• “Discovery Walks,” four family-friendly, self-guided walks through neighborhoods and parks in Atlanta, featuring free maps with cool science facts about each location. 
• “City Science Quest,” an app-based game that allows participants to use a mobile device to uncover Atlanta’s science contributions and STEM careers by earning prizes through completing interactive “missions,” including many that involve exciting scientific research ongoing at Emory. 

Emory event highlights

While not ignoring the current reality, the tone of this year’s festival is hopeful and encouraging, Salaita says. Emory experts will headline events that showcase how scientists at Emory and around the world came together to produce effective, safe vaccines for the novel coronavirus in record time, and to address concerns of communities that have been especially hard hit by COVID-19. 

Another Emory highlight will be a hands-on, outdoor event to learn how to collect data on Georgia’s air quality. And, not to be missed, Emory chemistry students will engage families in a “Drive-In Demo Show” of dramatic displays of chemistry in action. 

Following is a roundup of some of the festival highlights featuring the Emory community. 

Community scientists and amateur sleuths are invited to a family friendly “Air Quality Scavenger Hunt,” on Saturday, March 13, from 11 a.m. to 3 p.m. in Atlanta’s Historic Fourth Ward Park. Participants will be provided hand-held air sensors and learn to measure the amount of particulate matter, or pollutants, in the air. Their mission will be to use clues to locate different areas around the park to collect air quality data for Eri Saikawa, associate professor of Emory’s Department of Environmental Sciences, and students in her lab. The COVID-19 safety measures for the outdoor event require participants to wear masks and to sign up in advance for half-hour time slots to pick up and return the air sensors. “This event is for anyone who enjoys solving puzzles and wants to be part of the solution when it comes to pollution,” Saikawa says. 

A related at-home or in-class competition led by Saikawa and her students is the “Georgia Air Quality Challenge” for grades 6 to 12. Grade school students will partner with Air Emory, an Emory student-led initiative that began to monitor air quality on campus and is now expanding statewide through a grant from the Environmental Protection Agency and the support of Science ATL and Education Enhanced. Registered grade school students will receive access to lessons and videos to learn about sources of pollution, current data for Georgia, and how air sensors can measure air quality. They will then be challenged to submit a proposal for where air sensors should be placed in local communities in order to fill the gap in air quality data for Georgia. The winners will be invited to present their proposals to an upcoming Georgia STEM day. 

“We want young people to understand the importance of monitoring air quality,” Saikawa says. “We also hope they learn more about sources of air pollution, who may be more vulnerable, and think about ways we might mitigate pollution.” 

Emory physicians will be featured in a series of virtual talks on COVID-19 vaccines.

Emory physician Zanthia Wiley, assistant professor in the School of Medicine’s Division of Infectious Diseases, will give a virtual talk on Saturday, March 13, at 10 a.m., entitled “COVID-19 Vaccines and Disparities in Black Communities: What You Need to Know.” Dr. Wiley, who is also the director of Antimicrobial Stewardship at Emory University Hospital Midtown, will discuss the importance of COVID-19 vaccination and the disproportionate effect that COVID-19 is having in minority communities. She will also take questions submitted directly by those attending the virtual talk. Wiley is a member of the Emory Department of Medicine’s Diversity, Equity and Inclusion Council and the Emory Collaborative Community Outreach and Health Disparities Research Initiative. 

A virtual talk on Tuesday, March 16, at 6 p.m., “COVID-19 Vaccines and Disparities in Latinx Communities: What You Need to Know,” features Emory physician Valeria Cantos, assistant professor in the School of Medicine’s Division of Infectious Diseases and an attending physician at Grady Memorial Hospital and the Grady Infectious Disease Clinic. She will give a bi-lingual talk, in Spanish and English, on vaccine truths, myths and the importance of vaccination. She will also take questions submitted by the audience. Dr. Santos is a lead co-investigator in a study looking at the efficacy of remdesivir in the treatment of hospitalized patients with COVID-19. She is also a co-investigator for the Moderna and Noravax vaccine clinical trials. 

“Vaccine Real Talk,” a virtual panel discussion, is is set for Thursday, March 18, at 7 p.m. The panel will be moderated by Maryn McKenna, a leading infectious disease journalist and a senior fellow in Emory’s Center for the Study of Human Health. The event will take on the topic of how COVID-19 vaccines work and how to best combat misinformation around them. Panelists will include Colleen Kraft, associate professor in Emory School of Medicine’s Division of Infectious Diseases and the director of Emory’s Clinical Virology Research Laboratory. 

At noon on March 18, Deboleena Roy, Emory senior sssociate dean of faculty, will lead a virtual panel discussion about scientists and their social responsibility titled “Citizen Nobel: The Pressure and Power of Winning the Ultimate Scientific Prize.” Roy is professor of neuroscience and behavioral biology with a joint appointment in women’s, gender and sexuality studies. The discussion will be based on the film “Citoyen Nobel,” which will be available free for registrants during the week of March 13 to 20. 

Book your free spot in advance and load your “pod” into the family vehicle for the “Drive-In Demo Show” on Saturday, March 20, at 11 a.m., noon and 1 p.m., in the parking lot of the First Christian Church in Decatur. Instead of a movie, this drive-in will feature live performances by Emory chemistry students, led by Doug Mulford, senior lecturer of chemistry, whose motto is “teaching with a pyrotechnic flair.” Viewers will remain safe in their cars as the masked, socially distanced Emory chemists make sparks fly. They will wrestle with polymers that grow as large as eels, turn gummy bears into flaming dragons, and make a liquid nitrogen cloud. The finale, of course, will feature a safe, but fiery, explosion! 

The Atlanta Science Festival is produced by more than 50 community partners, with major support from founders Emory, Georgia Tech and the Metro Atlanta Chamber, and sponsors UPS, International Paper, Georgia Power, Cox Enterprises, Mercer University and others.