Intuition and past research suggest that whether people deem someone trustworthy depends on that person’s past behavior and reputation for betrayal. But now, new work from psychologists at UCLA and Oklahoma State University is helping to explain why people might nevertheless trust certain cheaters and other betrayers.

When we benefit from someone’s betrayal, we tend to still regard that person as inherently trustworthy, the psychologists reported in a study published in Evolution and Human Behavior. Their experiments found that, although subjects tended to regard people who betrayed others as generally less trustworthy, when a person’s betrayal benefited the subject, that person was still thought to be worthy of trust.

At question is the role concepts like “trustworthiness” play in our relationships. According to the research team, inferences about someone’s trustworthiness are used for making adaptive choices — that is, choices that benefit us. So, while people might be attuned to whether someone has betrayed others in the past, the researchers predicted that people would also be attuned to certain relationship-based factors that impact how that person is viewed/trusted.

“Making decisions about whom to trust based only on whether that person has betrayed someone else might not be the best way to determine whether or not I can trust someone,” said study co-author and UCLA professor of psychology Jaimie Krems.

“Sure, if someone betrays other people, that could be a valuable cue that they might betray me — but not always. For example, think about that friend who always tells you other friends’ secrets but doesn’t share yours. This friend is betraying other people but enriching you with information,” Krems added.

This was the researchers’ main contention: The mind should be attuned to whether someone has a reputation for betrayal, yes, but also to how someone’s betrayal affects you.

The researchers designed experiments to test whether people deemed targets more trustworthy when the targets avoided betrayal — but also when the betrayal had different impacts on the subject.

In one series of experiments, participants were randomly assigned to read one of three vignettes describing their interaction with a target. The first experiment involved sharing secrets among friends, while the second involved romantic infidelity. The third described an interaction in the context of international relations, with participants acting as CIA agents attempting to cultivate a French official as a source.

The targets exhibited one of three behaviors: they did not betray anyone when they had the opportunity; they betrayed another person to the participant or betrayed the participant to someone else. For example, some targets did not share a secret, others shared a secret about someone else with the participant, and still others shared the participant’s secret with a third party. After reading the vignettes, participants rated the target’s trustworthiness on a 7-point scale with questions such as, “I would trust the target to keep my secrets.”

As intuition would predict, across all types of relationships, participants regarded targets as more trustworthy if they did not betray anyone and less trustworthy if they did. But people who betrayed were not all deemed equally untrustworthy. When betrayal benefited the participants, they still considered the target trustworthy. This pattern was largely consistent across friendships, romantic relationships and professional relationships.

The findings upheld the researchers’ hypothesis that judgments of trustworthiness are partly a reflection of the person’s disposition and idiosyncratic factors specific to the participant and the person at hand.

The findings show that while people might start with lofty ideals when it comes to trusting people, what they do in practice is often based more on self-interest.

The research was funded by the National Science Foundation.

Key takeaways

• Both intuition and past research suggest that whether people deem someone trustworthy depends on that person’s past behavior and reputation for betrayal.
• In a series of experiments, psychologists found that subjects regarded those who previously exhibited that behavior as less trustworthy. However, when the betrayal benefited them or had no effect on them, participants regarded the betrayer as trustworthy.
• This pattern was largely consistent across the types of relationships studied: friendships, romantic relationships and professional relationships.

The study, published today, January 9, in the journal Nature Water, finds that Earth’s vegetation stores about 786 km³ of water, only about 0.002% of the total amount of freshwater stored on Earth. The study also finds that the time it takes for water to flow through plants (referred to as transit or turnover time) and return to the atmosphere is among the fastest in the global water cycle, ranging from just five days in croplands to 18 days in evergreen needleleaf forests. The transit of water through plants is particularly fast in croplands, grasslands and savannas. The results underscore vegetation’s dynamic role in the water cycle. In comparison to the global annual median of 8.1 days for water to transit through plants from entry to exit, the water in lakes is estimated to take 17 years, and the water in glaciers is estimated to take 1600 years.

“We have known for a long time that most of the water that returns from the ground to the atmosphere does so through plants, but until now, we did not really know how long it took for that water to transit through plants. Our results show that the transit of water through plants occurs on the order of days, rather than months, years, or centuries, as it does in other parts of the water cycle,” said the study’s lead author Dr. Andrew Felton, who carried out the work as part of a U.S. Department of Agriculture Fellowship while at Chapman University and is now a professor at Montana State University.

The research team notes that by combining estimates of the transit of water through plants with the transit of water through the atmosphere (about 8-10 days) and the transit time of water through soil before being taken up by plants (about 60 to 90 days), they can begin to estimate the complete amount of time it takes for a drop of water to move through the terrestrial water cycle.

“Plants are the forgotten part of the global water cycle,” said Felton. “In many cases, plants are not even represented on water cycle diagrams, which is ironic because we already know they play this critical role in returning water from the ground to the atmosphere.”

To generate the estimates, the research team first calculated the amount of water stored in plants using data from NASA’s Soil Moisture Active Passive Mission (SMAP) satellite mission, which provided high-resolution estimates of the water in soils. The SMAP mission originally saw plants as interfering with the soil moisture measurements, and was correcting for their presence. The Chapman researchers found those corrections actually held valuable information for understanding the water cycle. The team combined estimates of plant water storage with cutting-edge estimates of the rates at which water is leaving plants to determine the transit time of water through vegetation. The result was five years of monthly water storage and transit time estimates at a spatial resolution of 9 km².

The research team also found that the transit time of water through vegetation varied considerably across different land cover types, climate and seasons. The transit time of water through croplands was significantly and consistently the fastest, with water transiting through plants in less than a day during the peak of the growing season.

“One important observation is that croplands around the world tend to have very similar and very fast transit times,” said Dr. Gregory Goldsmith, senior author and an associate professor of Biological Sciences at Chapman University. “This indicates that land use change may be homogenizing the global water cycle and contributing to its intensification by more rapidly recycling water back to the atmosphere where it can turn into heavy rain events.”

“The results suggest that the transit time of water through plants is likely to be very sensitive to events such as deforestation, drought and wildfire, which will fundamentally change the time it takes for water to flow through the water cycle,” Felton said.

The findings were made available online ahead of the next print edition of the journal Zoonoses and Public Health. Given the proximity of dogs to humans and the use of critically important antibiotics in companion animal medicine, the researchers reported, household dogs represent a risk for the spread of antimicrobial-resistant Salmonella. They explained that better awareness of the risk and proper hygiene could potentially help mitigate cross-species infections.

Salmonella infections in dogs can be clinical — showing signs or symptoms — or asymptomatic with numerous studies reporting Salmonella isolation from clinically healthy dogs, according to team leader Erika Ganda, assistant professor of food animal microbiomes, Penn State College of Agricultural Sciences. A major concern, she explained, is the closeness of humans and pet dogs that creates ample opportunity for Salmonella “zoonosis” — the disease transmitted to humans from animals — and pet-management decisions involving food contamination, improper food handling or both can increase the likelihood of infection.

To investigate antimicrobial-resistant Salmonella and the zoonotic potential of nontyphoidal Salmonella isolated from dogs and humans, the researchers leveraged existing biosurveillance infrastructure. Using the U.S. Food & Drug Administration’s Veterinary Laboratory Investigation and Response Network, they identified all nontyphoidal Salmonella strains isolated from domestic dogs between May 2017 and March 2023.

Then they matched the timing and location of those 87 cases to strains isolated from humans in the National Center for Biotechnology Information database maintained by the National Library of Medicine at the National Institutes of Health, which provides access to biomedical and genomic information. They found 77 suspected zoonotic cases — meaning the bacteria moved from a pet dog to a human — comprising 164 strains, collected from 17 states in the United States.

Strains isolated from dogs included diverse serovars, or distinct variations within the species of bacteria, with most being clinically relevant to human health, the researchers reported. While the datasets did not contain information on severity of infection or treatments, the researchers did find that all identified strains possessed antimicrobial resistance genes for drug classes deemed critically or highly important by the World Health Organization.

“We identified 16 nontyphoidal Salmonella isolates from humans closely related to more than one of six dog-associated strains,” said Sophia Kenney, a student in the molecular, cellular and integrative biosciences doctoral program, and in the Department of Animal Science, who spearheaded the study. “Collectively, our data emphasize the importance of antimicrobial stewardship and sustained biosurveillance beyond human and agriculture-associated veterinary medicine, using a ‘One Health’ framework, that accounts for all transmission points — including companion animals. One Health isan approach that recognizes that the health of people is closely connected to the health of animals and our shared environment.”

Antimicrobial stewardship in companion animal veterinary medicine is crucial for mitigating antimicrobial resistance within the One Health model, Kenney explained.

“Especially with Salmonella, we think about the role of agriculture and transmission — we think about eggs, we think about beef. But the thing is, we don’t let cows sleep in our beds or lick our faces, but we do dogs,” she said. “We have this close bond with companion animals in general, and we have a really close interface with dogs. So, we asked the question: What’s the role of companion animals in transmission of zoonotic disease like Salmonella, since they can get it. Salmonella infections in dogs are not common but we’re aware of foodborne outbreaks related to pet treats or from contact with contaminated pet food and improper food handling.”

Study co-author Nkuchia M’ikanatha, lead epidemiologist for the Pennsylvania Department of Health and an affiliated researcher in Penn State’s Department of Food Science, referred to an outbreak of multidrug-resistant Salmonella infections in people linked to pig ear pet treats in the United States a few years ago that sickened 154 people across 34 states.

“This reminds us that simple hygiene practices such as hand washing are needed to protect both our furry friends and ourselves — our dogs are family but even the healthiest pup can carry Salmonella,” he said. “Salmonella is a quintessential human microbe, its presence intertwined with our history since the dawn of agriculture. Emerging research suggests this pathogen may have shadowed humanity for some 10,000 years, coinciding with the rise of animal domestication. With nearly 40% of Pennsylvania households and over half of U.S. homes including dogs, we must respect the enduring threat of Salmonella and remain vigilant in preventing its spread within our families.”

Bacteria are never entirely “bad” or “good” — their role depends on the context, Ganda pointed out. While some bacteria, like Salmonella, can pose serious health risks, others are essential for maintaining our health and the health of our pets. It is important to remain vigilant and informed about potential risks, especially when living closely with animals, she added.

“At the same time, several studies highlight the significant physical and mental health benefits of owning a dog, including reduced stress and increased physical activity,” Ganda said. “Our goal is not to discourage pet ownership but to ensure that people are aware of potential risks and take simple steps, like practicing good hygiene, to keep both their families and their furry companions safe.”

This work was supported by funds from the U.S. Department of Agriculture, the U.S. Centers for Disease Control and Prevention, the National Institutes of Health and the U.S. Food and Drug Administration.

Ants learn from experience. This has been demonstrated by a team of evolutionary biologists from the University of Freiburg, led by Dr Volker Nehring, research associate in the Evolutionary Biology and Animal Ecology group, and doctoral student Mélanie Bey. The researchers repeatedly confronted ants with competitors from another nest. The test ants remembered the negative experiences they had during these encounters: when they encountered ants from a nest they had previously experienced as aggressive, they behaved more aggressively towards them than towards ants from nests unknown to them. Ants that encountered members of a nest from which they had previously only encountered passive ants were less aggressive. The biologists published their results in the journal Current Biology.

Ants are aggressive towards their neighbours

Ants use odours to distinguish between members of their own nest and those from other nests. Each nest has its own specific scent. Previous studies have already shown that ants behave aggressively towards their nearest neighbours in particular. They are especially likely to open their mandibles and bite, or spray acid and kill their competitors. They are less likely to carry out such aggressive manoeuvres against nests that are further away from their own. Until now, it was unclear why this is the case. Nehring’s team has now discovered that ants remember the smell of attackers. This is why they are more aggressive when confronted with competitors from nests they are familiar with.

More aggressive behaviour towards competitors from familiar nests

The scientists conducted an experiment in two phases. In the first phase, ants gained various experiences: one group encountered ants from their own nest, the second group encountered aggressive ants from a rival nest A, and the third group encountered aggressive ants from rival nest B. A total of five encounters took place on consecutive days, with each encounter lasting one minute.

In the subsequent test phase, the researchers examined how the ants from the different groups behaved when they encountered competitors from nest A. The ants that had already been confronted with conspecifics from this nest in the first phase behaved significantly more aggressively than those from the other two groups.

To test the extent to which the higher aggression arises from the behaviour of ants from a particular nest, the scientists repeated the experiment in a slightly modified form. In the first phase, they now distinguished between encounters with aggressive and passive ants. They ensured that an ant behaved passively by cutting off its antennae. In phase two of the experiment, the ants that had previously only encountered passive competitors behaved significantly less aggressively.

“We often have the idea that insects function like pre-programmed robots,” says Nehring. “Our study provides new evidence that, on the contrary, ants also learn from their experiences and can hold a grudge.” Next, Nehring and his team will investigate whether and to what extent ants adapt their olfactory receptors to their experiences, thus reflecting what they have learned at this level as well.

• Mélanie Bey conducted her doctorate under Dr. Volker Nehring. Rebecca Endermann, Christina Raudies and Jonas Steinle are former bachelor’s and master’s students in the Evolutionary Biology and Animal Ecology working group.
• The research was funded by the German Research Foundation (project number NE1969/6-1).

The technology could immediately enable low-cost, efficient real-time monitoring in industrial settings, such as tracking the condition of manufacturing robots or detecting gas leaks in refineries, by eliminating the need for power-hungry signal transmitters. The researchers said that with some engineering improvements, the technology could be used for large-scale applications like smart cities and agriculture.

The technology is an advanced version of a device that transmits data in a wireless system, commonly known as a tag. The new tag can support data transmission for a large network of devices using a technique called backscattering. This is where a central reader sends a signal to a sensor tag to gather information, and the tag reflects this ambient signal directly back to the reader. Backscattering is already used in simple systems like smart payment and building entry cards, but until now has only been possible at low frequencies.

The low frequency limit poses a problem when many devices try to communicate at the same time because when more signals are introduced, they are more likely to run into one another and get jumbled up. Conventional backscatter designs also have slow communication speeds, as lower frequency signals have limitations on how much information can travel back and forth at once.

The new tag, developed by researchers at Princeton, Rice University and Brown University, is the first of its kind that can use backscattering in the sub-terahertz range, a high-frequency portion of the radio spectrum. This range can support high-speed data transmission across broad bandwidths. The development means it could be possible to power signal transmission for dense networks of devices using passive tags, saving significant power and infrastructure compared to conventional wireless systems.

“I believe this technology will find applications in many interesting settings,” said Yasaman Ghasempour, assistant professor of electrical and computer engineering at Princeton and the study’s principal investigator. “Despite the conventional wisdom, this paper shows that it is possible to have low-power, scalable communication in the sub-terahertz range.”

The paper was published Oct. 9 in Nature Communications.

Using backscattering at higher frequencies is challenging because the signals are more susceptible to fading as they propagate and must be very precise to travel long distances. “The reader has to form a narrow pencil-shaped beam to shine into the tag’s precise location, and the low-power tag should do the same without consuming any power. That’s the real challenge,” Ghasempour said.

Traditional backscatter tags reflect signals back to their source using simple antennas that typically broadcast the energy in all directions, causing only a portion of the energy to reach back to the reader. While some advanced tags can adjust the direction of their signal, their ability to do so is limited, and they’re restricted to a narrow range of frequencies. Ghasempour said that achieving sub-terahertz backscattering required the team to rethink the entire architecture of the tag. “It wouldn’t work to use the same old hardware design and scale it up,” she said.

To address these limitations, the researchers came up with an entirely new antenna structure. The new antennas allow the direction of the signal to change automatically in response to changes in frequency. By doing this, the tag can steer the signal to enable longer range communication and avoid interference from other signals. In other words, the interference footprint of each tag is limited in spatial and spectral domains.

Ghasempour said she hopes that others will read this paper and find engineering improvements for advanced applications. By implementing a way to amplify signals in the system at low costs, for example, the technology could power sensor networks across cities to monitor air quality or traffic flow.

The tags could be placed on traffic signs to be detected by self-driving cars, as they can use radio waves to convey messages like “stop” or “yield” even when visibility is blocked by fog or snow. In agriculture, the technology could help create expansive networks of soil sensors across fields or forests, providing real-time data on moisture levels or temperature.

Ghasempour said that developing low-power data modulators in these kinds of systems is an active area of research, and that this innovation is a step toward decreasing cost and power consumption for the entire wireless system.

Lithium-ion batteries and other rechargeable batteries based on metal ions provide our portable devices with electricity, power vehicles, and store solar and wind energy. They work well — as long as it is warm. As temperatures drop, the performance of these batteries can decrease sharply — a problem for electric cars, aerospace, and military applications. Countermeasures such as integrated heaters, improved electrolytes, or electrode coatings increase the cost and complexity of battery production or reduce performance.

One of the causes of the cold problem is the slowed diffusion of lithium ions within the electrode material. A team from Donghua University and Fudan University in Shanghai, as well as Inner Mongolia University in Hohhot has proposed a new approach to tackling this issue: electrodes made of electrochemical energy-storage materials with negative thermal expansion (NTE), such as lithium titanium phosphate LiTi₂(PO₄)₃ (LTP). Led by Liming Wu, Chunfu Lin, and Renchao Che, the team used LTP as a model substance to demonstrate that electrode materials with NTE properties can provide good performance at low temperatures.

Analysis of the crystal structure revealed a three-dimensional lattice of TiO₆ octahedra and PO₄ tetrahedra with an open, flexible structure that contains both “cavities” and “channels,” where lithium ions can lodge. When cooled, the structure stretches along one of its crystal axes. By using spectrometric and electron microscopic analyses in conjunction with computer modeling, the team determined that the vibrational modes of the atoms change at low temperature. This increases the occurrence of special transverse vibrations of certain oxygen atoms, increasing their distances from each other and widening the cavities in the lattice. This facilitates storage and transport of the lithium ions. At −10 °C, their diffusion rate is still at 84% of the value obtained at 25 °C. Electrochemical tests on carbon-coated LTP at −10 °C also showed good electrochemical performance with high capacity and a high rate capability, as well as a high retention of capacity over 1000 charge/discharge cycles.

Materials with negative thermal expansion are thus highly promising for use as an electrode material in lithium-ion batteries in cold environments.