Letters in 2019

A daily, city-level happiness metric constructed from the sentiment expressed in 210 million tweets on Sina Weibo from 144 cities shows that high levels of air pollution significantly reduce Chinese urbanites’ expressed happiness on social media.

Using data from 765 million online music plays chosen by 1 million individuals in 51 countries, Park et al. reveal diurnal and seasonal affective rhythms in musical intensity that are consistent across diverse cultures and demographic groups. They also report differences in baseline preferences for musical intensity across cultures and ages.

An individual’s social ties contain up to 95% of the potential predictive accuracy achievable about that individual. In principle, a social platform may therefore profile an individual from their ties only, without access to their data.

Askelund et al. show that remembering more specific positive life experiences is associated with fewer negative self-related thoughts and lower levels of stress hormones in a study of 427 adolescents at risk for depression.

Why do we continue processing external events during sleep, yet remain unresponsive? Legendre et al. use electroencephalography to show that sleepers enter a ‘standby mode’, continuing to track relevant signals but doing so transiently.

In the United States, France and Germany, as peoples’ opposition to genetically modified (GM) foods becomes more extreme, their self-rated understanding of genetic modification increases, but objectively, their knowledge of the science behind genetic modification tends to be poorer.

Nearby small objects appear larger than distal large objects, reflecting a dissociation between perceived and actual object size. Collegio et al. show that inferences of true object size scale spatial attention to objects.