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.

 

In this Policy Forum, John Bistline and colleagues analyze the potential impacts of the U.S. Environmental Protection Agency’s finalized power plant rules regarding greenhouse gas emissions. Using nine models of the U.S. electric sector and energy systems, the researchers found that the rules would speed up the reduction of emissions in the power sector. Under the rules, the levels of carbon dioxide emitted by the sector would be 61%-81% below 2005 levels by 2040. Under current policies, emission levels would be 51% to 83% below 2005 levels by 2040, indicating that the finalized rules would narrow the range of emission levels. As the U.S. electric power sector is the second-highest greenhouse gas emitting sector in the world’s second highest emitting country, the researchers suggest their analysis can help guide utilities and lawmakers as they make technology and compliance changes in response to the new rules. The models by Bistline et al. also show that the costs of regulations under the new rules are limited relative to costs without the rules, mainly due to the cost-effectiveness of coal CO₂ reductions and flexible compliance options. The rules also reduce co-pollutant emissions that “can bring near-term air quality benefits and improve public health in environmental justice communities, which have historically been disproportionately impacted by pollution, and beyond,” Bistline et al. write. However, the fate of the EPA finalized rules is uncertain under a new presidential administration, the researchers note.

Male and female mice both prefer social interaction with female mice under normal conditions, but both switch to preferring males when their survival is threatened, according to a new study by Anqi Wei and colleagues. These preferences are mediated by different neuronal circuitry in male and female mice related to dopaminergic neurons in the brain’s ventral tegmental area, the researchers found. The findings offer a clearer picture of the underlying biology of socio-sexual preferences. These preferences are essential for successful reproduction, but also play a significant role in protective and supportive behaviors that are vital for health and survival among mammals. The researchers examined how socio-sexual preferences can be altered by comparing how mice interacted with and without the presence of trimethylthiazoline, a potent smell that mice respond to as a survival threat. In male mice, neuronal projections from the ventral tegmental area go to the brain’s nucleus accumbens to mediate female socio-sexual preference, but to the medial preoptic area to mediate male preference. In female mice, the firing pattern of neuronal projections from the ventral tegmental area to the nucleus accumbens mediates the switch to preferring male companions under survival stress. Bitna Joo and Kay M. Tye discuss these results in a related Perspective.

A new study by UC San Francisco has found that menopause revs up the progression of multiple sclerosis (MS). 

There is just over a month left to register for the 2025 AAAS Annual Meeting in Boston, Mass. from Feb. 13 – 15. Eligible journalists, public information officers, and journalism professors and students can attend for free.