The required size of cluster randomized trials of nonpharmaceutical interventions in epidemic settings.

To control the SARS-CoV-2 pandemic and future pathogen outbreaks requires an understanding of which nonpharmaceutical interventions are effective at reducing transmission. Observational studies, however, are subject to biases that could erroneously suggest an impact on transmission, even when there is no true effect. Cluster randomized trials permit valid hypothesis tests of the effect of interventions on community transmission. While such trials could be completed in a relatively short period of time, they might require large sample sizes to achieve adequate power. However, the sample sizes required for such tests in outbreak settings are largely undeveloped, leaving unanswered the question of whether these designs are practical. We develop approximate sample size formulae and simulation-based sample size methods for cluster randomized trials in infectious disease outbreaks. We highlight key relationships between characteristics of transmission and the enrolled communities and the required sample sizes, describe settings where trials powered to detect a meaningful true effect size may be feasible, and provide recommendations for investigators in planning such trials. The approximate formulae and simulation banks may be used by investigators to quickly assess the feasibility of a trial, followed by more detailed methods to more precisely size the trial. For example, we show that community-scale trials requiring 220 clusters with 100 tested individuals per cluster are powered to identify interventions that reduce transmission by 40% in one generation interval, using parameters identified for SARS-CoV-2 transmission. For more modest treatment effects, or when transmission is extremely overdispersed, however, much larger sample sizes are required.

Global Behaviors, Perceptions, and the Emergence of Social Norms at the Onset of the COVID-19 Pandemic.

We conducted a large-scale survey covering 58 countries and over 100,000 respondents between late March and early April 2020 to study beliefs and attitudes towards citizens' and governments' responses at the onset of the COVID-19 pandemic. Most respondents reported holding normative beliefs in support of COVID-19 containment measures, as well as high rates of adherence to these measures. They also believed that their government and their country's citizens were not doing enough and underestimated the degree to which others in their country supported strong behavioral and policy responses to the pandemic. Normative beliefs were strongly associated with adherence, as well as beliefs about others' and the government's response. Lockdowns were associated with greater optimism about others' and the government's response, and improvements in measures of perceived mental well-being; these effects tended to be larger for those with stronger normative beliefs. Our findings highlight how social norms can arise quickly and effectively to support cooperation at a global scale.

Falling living standards during the COVID-19 crisis: Quantitative evidence from nine developing countries.

Despite numerous journalistic accounts, systematic quantitative evidence on economic conditions during the ongoing COVID-19 pandemic remains scarce for most low- and middle-income countries, partly due to limitations of official economic statistics in environments with large informal sectors and subsistence agriculture. We assemble evidence from over 30,000 respondents in 16 original household surveys from nine countries in Africa (Burkina Faso, Ghana, Kenya, Rwanda, Sierra Leone), Asia (Bangladesh, Nepal, Philippines), and Latin America (Colombia). We document declines in employment and income in all settings beginning March 2020. The share of households experiencing an income drop ranges from 8 to 87% (median, 68%). Household coping strategies and government assistance were insufficient to sustain precrisis living standards, resulting in widespread food insecurity and dire economic conditions even 3 months into the crisis. We discuss promising policy responses and speculate about the risk of persistent adverse effects, especially among children and other vulnerable groups.

Interventions to improve adherence to antenatal and postnatal care regimens among pregnant women in sub-Saharan Africa: a systematic review.

BACKGROUND: Pregnant women in sub-Saharan Africa tend to have low adherence to antenatal and postnatal care regimens, contributing to high infant and child mortality rates. Despite low adherence figures and the high returns from attending antenatal and postnatal care visits, research on interventions to improve adherence is in its infancy. Our aim was to determine the effectiveness of existing interventions to improve adherence to antenatal and postnatal care regimens among pregnant women in sub-Saharan Africa. METHODS: Full text, peer-reviewed articles, published in English and listed in PubMed or PsycINFO through January 2018 were identified in a systematic review. Studies were restricted to randomized controlled trials only and had to assess intervention impact on antenatal and postnatal care adherence, operationalized as the frequency of visits attended. Two reviewers independently screened papers for inclusion and evaluated the risk of systematic error in each study using the Cochrane risk of bias tool. Any discrepancies were reconciled by a third independent reviewer. RESULTS: The initial search generated 186 articles, of which, five met our inclusion criteria. Due to the small sample size and methodological variation across studies, a pooled effect size estimate could not be obtained. Therefore, effects on antenatal and postnatal care adherence were examined and reported at the individual study level. None of the interventions were directly aimed at improving adherence, but two of the five, both behavioral interventions, demonstrated effectiveness in increasing antenatal care (rate ratio 5.86, 95% CI 2.6-13.0, p<0.0001) and postnatal care adherence (31.3%, 95% CI 15.4-47.2, p=0.0009), respectively. Three home visit interventions had no effect on antenatal care adherence. Although the risk of bias was unclear or high in some cases, it remained low in most categories across studies. CONCLUSIONS: Results point to a large gap in the literature on interventions to address antenatal and postnatal care adherence in sub-Saharan Africa. Interventions drawing upon the executive function literature and the promising results of the behavioral interventions reviewed here are urgently needed to address these gaps. TRIAL REGISTRATION: The review was prospectively registered with PROSPERO, id number https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=88152, on February 7, 2018.

Psychological origins of the Industrial Revolution: Why we need causal methods and historians.

Did affluence lead to psychological changes such as reduced discounting, and did these changes facilitate the innovation associated with the Industrial Revolution? I argue that claims of this sort are best made when they can be supported by causal evidence and good psychological measurement. When we have neither identifying variation nor adequate measures, the toolbox of psychologists is not useful.

Is there a social cost of randomization?

Randomized controlled trials, which randomly allocate benefits to a treatment group and not a control group, ascribe differences in post-treatment welfare to the benefits being allocated. However, it is possible that potential recipients' welfare is not only affected by the receipt of the program, but also by the allocation mechanism (procedural utility). In this paper, we ask whether potential recipients support or oppose random allocation of financial benefits, by allowing them to reward or punish an allocator conditional on her choice of allocation mechanism: direct allocation to one recipient vs. randomization among potential recipients. We find that when potential recipients have equal endowments, they on average reward the allocator for randomizing. When instead there is inequality in the potential recipients' endowments, the relatively poorer recipients punish allocators who randomize, while the relatively richer potential recipients neither reward nor punish the allocator for randomizing. Our results suggest that an allocator who chooses to randomize between potential recipients with unequal endowments imposes a social cost on the relatively poorer potential recipients.

Social determinants of mental disorders and the Sustainable Development Goals: a systematic review of reviews.

Mental health has been included in the UN Sustainable Development Goals. However, uncertainty exists about the extent to which the major social determinants of mental disorders are addressed by these goals. The aim of this study was to develop a conceptual framework for the social determinants of mental disorders that is aligned with the Sustainable Development Goals, to use this framework to systematically review evidence regarding these social determinants, and to identify potential mechanisms and targets for interventions. We did a systematic review of reviews using a conceptual framework comprising demographic, economic, neighbourhood, environmental events, and social and culture domains. We included 289 articles in the final Review. This study sheds new light on how the Sustainable Development Goals are relevant for addressing the social determinants of mental disorders, and how these goals could be optimised to prevent mental disorders.

The effect of hydrocortisone administration on intertemporal choice.

Intertemporal choices - decisions involving trade-offs of outcomes at different points in time - are often made under stress. Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, resulting in the release of corticosteroids. Recent studies provide evidence that corticosteroids can induce rapid non-genomic effects focused on immediate resolution of the stressful situation, followed by slower genomic effects focused on long-term recovery after stress. It remains unknown, however, how corticosteroids affect intertemporal choice. We randomly assigned healthy men to receive either 10 mg hydrocortisone or a placebo before measuring intertemporal choice. To target time-dependent effects, hydrocortisone was administered either 195 or 15 min before choice elicitation, while a placebo was administered at the other timepoint, in a double-blind design. Intertemporal choices were elicited by offering subjects decisions between small rewards available sooner vs. large rewards available later. We demonstrate a time-dependent effect of hydrocortisone administration on intertemporal choice: when tested 15 min after hydrocortisone administration, subjects showed a strongly increased preference for the small, soon reward over the larger, delayed reward. In contrast, this effect was not found when testing occurred 195 min after hydrocortisone administration. Together, these results suggest that the physiological effects of acute, but not delayed, stress may increase temporal discounting.

Measuring self-efficacy, executive function, and temporal discounting in Kenya.

Developing countries have low adherence to medical regimens like water chlorination or antenatal and postnatal care, contributing to high infant and child mortality rates. We hypothesize that high levels of stress affect adherence through temporal discounting, self-efficacy, and executive control. Measurement of these constructs in developing countries requires adaptation of existing measures. In the current study, we adapt psychological scales and behavioral tasks, measuring each of these three constructs, for use among adults in Kenya. We translated and back-translated each measure to Kiswahili and conducted cognitive interviewing to establish cultural acceptability, refined existing behavioral tasks, and developed new ones. Then, in a laboratory session lasting 3 h, participants (N=511) completed the adapted psychological inventories and behavioral tasks. We report the psychometric properties of these measures. We find relatively low reliability and poor correlational evidence between psychological scales and behavioral tasks measuring the same construct, highlighting the challenges of adapting measures across cultures, and suggesting that assays within the same domain may tap distinct underlying processes.

Stuff goes wrong, so act now.

Pepper & Nettle make an ambitious and compelling attempt to isolate a common cause of what they call the behavioral constellation of deprivation. We agree with the authors that limited control can indeed help explain part of the difference in observed present-oriented behavior between the poor and the rich. However, we suggest that mortality risk is not the primary mechanism leading to this apparent impatience.

Development of Behavioral Control and Associated vmPFC-DLPFC Connectivity Explains Children's Increased Resistance to Temptation in Intertemporal Choice.

Human civilization is based on the successful pursuit of long-term goals, requiring the ability to forego immediate pleasure for the sake of larger future rewards. This ability improves with age, but the precise cognitive and neural mechanisms underlying its development remain elusive. The developmental changes could result either from younger children valuing immediate rewards more strongly or because older children become better at controlling their impulses. By implementing 2 tasks, a choice-independent valuation task and an intertemporal choice task, both behaviorally and using fMRI in twenty 6- to 13-year old children, we show developmental improvements in behavioral control to uniquely account for age-related changes in temporal discounting. We show further that overcoming temptation during childhood occurs as a function of an age-related increase in functional coupling between value signals in the ventromedial prefrontal cortex and brain regions dedicated to behavioral control, such as left dorsolateral prefrontal cortex during choice. These findings can help to devise measures that reduce the substantial costs of impatience to society.

THE SHORT-TERM IMPACT OF UNCONDITIONAL CASH TRANSFERS TO THE POOR: EXPERIMENTAL EVIDENCE FROM KENYA.

We use a randomized controlled trial to study the response of poor households in rural Kenya to unconditional cash transfers from the NGO GiveDirectly. The transfers differ from other programs in that they are explicitly unconditional, large, and concentrated in time. We randomized at both the village and household levels; furthermore, within the treatment group, we randomized recipient gender (wife versus husband), transfer timing (lump-sum transfer versus monthly installments), and transfer magnitude (US$404 PPP versus US$1,525 PPP). We find a strong consumption response to transfers, with an increase in household monthly consumption from $158 PPP to $193 PPP nine months after the transfer began. Transfer recipients experience large increases in psychological well-being. We find no overall effect on levels of the stress hormone cortisol, although there are differences across some subgroups. Monthly transfers are more likely than lump-sum transfers to improve food security, whereas lump-sum transfers are more likely to be spent on durables, suggesting that households face savings and credit constraints. Together, these results suggest that unconditional cash transfers have significant impacts on economic outcomes and psychological well-being.

On the psychology of poverty.

Poverty remains one of the most pressing problems facing the world; the mechanisms through which poverty arises and perpetuates itself, however, are not well understood. Here, we examine the evidence for the hypothesis that poverty may have particular psychological consequences that can lead to economic behaviors that make it difficult to escape poverty. The evidence indicates that poverty causes stress and negative affective states which in turn may lead to short-sighted and risk-averse decision-making, possibly by limiting attention and favoring habitual behaviors at the expense of goal-directed ones. Together, these relationships may constitute a feedback loop that contributes to the perpetuation of poverty. We conclude by pointing toward specific gaps in our knowledge and outlining poverty alleviation programs that this mechanism suggests.

No effects of psychosocial stress on intertemporal choice.

Intertemporal choices - involving decisions which trade off instant and delayed outcomes - are often made under stress. It remains unknown, however, whether and how stress affects intertemporal choice. We subjected 142 healthy male subjects to a laboratory stress or control protocol, and asked them to make a series of intertemporal choices either directly after stress, or 20 minutes later (resulting in four experimental groups). Based on theory and evidence from behavioral economics and cellular neuroscience, we predicted a bidirectional effect of stress on intertemporal choice, with increases in impatience or present bias immediately after stress, but decreases in present bias or impatience when subjects are tested 20 minutes later. However, our results show no effects of stress on intertemporal choice at either time point, and individual differences in stress reactivity (changes in stress hormone levels over time) are not related to individual differences in intertemporal choice. Together, we did not find support for the hypothesis that psychosocial laboratory stressors affect intertemporal choice.

The role of testosterone in social interaction.

Although animal researchers established the role of testosterone as a 'social hormone' decades ago, the investigation of its causal influence on human social behaviors has only recently begun. Here, we review and discuss recent studies showing the causal effects of testosterone on social interactions in animals and humans, and outline the basic neurobiological mechanisms that might underlie these effects. Based on these recent findings, we argue that the role of testosterone in human social behavior might be best understood in terms of the search for, and maintenance of, social status.

Both sides retaliate in the Israeli-Palestinian conflict.

Ending violent international conflicts requires understanding the causal factors that perpetuate them. In the Israeli-Palestinian conflict, Israelis and Palestinians each tend to see themselves as victims, engaging in violence only in response to attacks initiated by a fundamentally and implacably violent foe bent on their destruction. Econometric techniques allow us to empirically test the degree to which violence on each side occurs in response to aggression by the other side. Prior studies using these methods have argued that Israel reacts strongly to attacks by Palestinians, whereas Palestinian violence is random (i.e., not predicted by prior Israeli attacks). Here we replicate prior findings that Israeli killings of Palestinians increase after Palestinian killings of Israelis, but crucially show further that when nonlethal forms of violence are considered, and when a larger dataset is used, Palestinian violence also reveals a pattern of retaliation: (i) the firing of Palestinian rockets increases sharply after Israelis kill Palestinians, and (ii) the probability (although not the number) of killings of Israelis by Palestinians increases after killings of Palestinians by Israel. These findings suggest that Israeli military actions against Palestinians lead to escalation rather than incapacitation. Further, they refute the view that Palestinians are uncontingently violent, showing instead that a significant proportion of Palestinian violence occurs in response to Israeli behavior. Well-established cognitive biases may lead participants on each side of the conflict to underappreciate the degree to which the other side's violence is retaliatory, and hence to systematically underestimate their own role in perpetuating the conflict.

You shouldn't have: your brain on others' crimes.

Our legal system requires assigning responsibility for crimes and deciding on appropriate punishments. A new fMRI study by Buckholtz et al. in this issue of Neuron reveals that the right dorsolateral prefrontal cortex (rDLPFC) plays a key role in these cognitive processes. This finding sheds light on the neural mechanisms underlying moral judgment from a third-party perspective.