Population flow drives spatio-temporal distribution of COVID-19 in China.

Sudden, large-scale and diffuse human migration can amplify localized outbreaks of disease into widespread epidemics1-4. Rapid and accurate tracking of aggregate population flows may therefore be epidemiologically informative. Here we use 11,478,484 counts of mobile phone data from individuals leaving or transiting through the prefecture of Wuhan between 1 January and 24 January 2020 as they moved to 296 prefectures throughout mainland China. First, we document the efficacy of quarantine in ceasing movement. Second, we show that the distribution of population outflow from Wuhan accurately predicts the relative frequency and geographical distribution of infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) until 19 February 2020, across mainland China. Third, we develop a spatio-temporal 'risk source' model that leverages population flow data (which operationalize the risk that emanates from epidemic epicentres) not only to forecast the distribution of confirmed cases, but also to identify regions that have a high risk of transmission at an early stage. Fourth, we use this risk source model to statistically derive the geographical spread of COVID-19 and the growth pattern based on the population outflow from Wuhan; the model yields a benchmark trend and an index for assessing the risk of community transmission of COVID-19 over time for different locations. This approach can be used by policy-makers in any nation with available data to make rapid and accurate risk assessments and to plan the allocation of limited resources ahead of ongoing outbreaks.

The Role of Hedonic Behavior in Reducing Perceived Risk.

Understanding how human populations naturally respond to and cope with risk is important for fields ranging from psychology to public health. We used geophysical and individual-level mobile-phone data (mobile-apps, telecommunications, and Web usage) of 157,358 victims of the 2013 Ya'an earthquake to diagnose the effects of the disaster and investigate how experiencing real risk (at different levels of intensity) changes behavior. Rather than limiting human activity, higher earthquake intensity resulted in graded increases in usage of communications apps (e.g., social networking, messaging), functional apps (e.g., informational tools), and hedonic apps (e.g., music, videos, games). Combining mobile data with a field survey ( N = 2,000) completed 1 week after the earthquake, we use an instrumental-variable approach to show that only increases in hedonic behavior reduced perceived risk. Thus, hedonic behavior could potentially serve as a population-scale coping and recovery strategy that is often missing in risk management and policy considerations.

Emergency communications after earthquake reveal social network backbone of important ties.

Social networks provide a basis for collective resilience to disasters. Combining the quasi-experimental context of a major earthquake in Ya'an, China, with anonymized mobile telecommunications records regarding 91,839 Ya'an residents, we use initial bursts of postdisaster communications (e.g. choice of alter, order of calls, and latency) to reveal the "important ties" that form the social network backbone. We find that only 26.8% of important ties activated during the earthquake were the strongest ties during normal times. Many important ties were hitherto latent and weak, only to become persistent and strong after the earthquake. We show that which ties activated during a sudden disaster are best predicted by the interaction of embeddedness and tie strength. Moreover, a backbone of important ties alone (without the inclusion of weak ties ordinarily seen as important to bridge communities) is sufficient to generate a hierarchical structure of social networks that connect a disaster zone's disparate communities.

Triadic embeddedness structure in family networks predicts mobile communication response to a sudden natural disaster.

Kinship networks are a fundamental social unit in human societies, and like social networks in general, provide social support in times of need. Here, we investigate the impact of sudden environmental shock, the Ms 7.0 2013 Ya'an earthquake, on the mobile communications patterns of local families, which we operationalize using anonymized individual-level mobile telecommunications metadata from family plan subscribers of a major carrier (N = 35,565 people). We demonstrate that families' communications dynamics after the earthquake depended on their triadic embeddedness structure, a structural metric we propose that reflects the number of dyads in a family triad that share social ties. We find that individuals in more embedded family structures were more likely to first call other family plan members and slower in calling non-family ties immediately after the earthquake; these tendencies were stronger at higher earthquake intensity. In the weeks after the event, individuals in more embedded family structures had more reciprocal communications and contacted more social ties in their broader social network. Overall, families that are structurally more embedded displayed higher levels of intra-family coordination and mobilization of non-family social connections.

When does playing hard to get increase romantic attraction?

Folk wisdom suggests playing hard to get is an effective strategy in romantic attraction. However, prior research has yielded little support for this belief. This article seeks to reconcile these contrasting views by investigating how 2 hitherto unconsidered factors, (a) the asymmetry between wanting (motivational) and liking (affective) responses and (b) the degree of psychological commitment, can determine the efficacy of playing hard to get. We propose that person B playing hard to get with person A will simultaneously increase A's wanting but decrease A's liking of B. However, such a result will only occur if A is psychologically committed to pursuing further relations with B; otherwise, playing hard to get will decrease both wanting and liking. Two studies confirm these propositions. We discuss implications for interpersonal attraction and the interplay between emotion and motivation in determining preferences.

The preference for potential.

When people seek to impress others, they often do so by highlighting individual achievements. Despite the intuitive appeal of this strategy, we demonstrate that people often prefer potential rather than achievement when evaluating others. Indeed, compared with references to achievement (e.g., "this person has won an award for his work"), references to potential (e.g., "this person could win an award for his work") appear to stimulate greater interest and processing, which can translate into more favorable reactions. This tendency creates a phenomenon whereby the potential to be good at something can be preferred over actually being good at that very same thing. We document this preference for potential in laboratory and field experiments, using targets ranging from athletes to comedians to graduate school applicants and measures ranging from salary allocations to online ad clicks to admission decisions.