Exposure to opposing views on social media can increase political polarization.

There is mounting concern that social media sites contribute to political polarization by creating "echo chambers" that insulate people from opposing views about current events. We surveyed a large sample of Democrats and Republicans who visit Twitter at least three times each week about a range of social policy issues. One week later, we randomly assigned respondents to a treatment condition in which they were offered financial incentives to follow a Twitter bot for 1 month that exposed them to messages from those with opposing political ideologies (e.g., elected officials, opinion leaders, media organizations, and nonprofit groups). Respondents were resurveyed at the end of the month to measure the effect of this treatment, and at regular intervals throughout the study period to monitor treatment compliance. We find that Republicans who followed a liberal Twitter bot became substantially more conservative posttreatment. Democrats exhibited slight increases in liberal attitudes after following a conservative Twitter bot, although these effects are not statistically significant. Notwithstanding important limitations of our study, these findings have significant implications for the interdisciplinary literature on political polarization and the emerging field of computational social science.

Centre-based day care for children younger than five years of age in high-income countries.

BACKGROUND: A large proportion of children younger than five years of age in high-income countries experience significant non-parental care. Centre-based day care services may influence the development of children and the economic situation of parents. OBJECTIVES: To assess the effects of centre-based day care without additional interventions (e.g. psychological or medical services, parent training) on the development and well-being of children and families in high-income countries (as defined by the World Bank 2011). SEARCH METHODS: In April 2014, we searched CENTRAL, Ovid MEDLINE, EMBASE, PsycINFO, the Education Resources Information Center (ERIC) and eight other databases. We also searched two trials registers and the reference lists of relevant studies. SELECTION CRITERIA: We included randomised and quasi-randomised controlled trials of centre-based day care for children younger than five years of age. We excluded studies that involved co-interventions not directed toward children (e.g. parent programmes, home visits, teacher training). We included the following outcomes: child cognitive development (primary outcome), child psychosocial development, maternal and family outcomes and child long-term outcomes. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed the risk of bias and extracted data from the single included study. We contacted investigators to obtain missing information. MAIN RESULTS: We included in the review one trial, involving 120 families and 143 children. Risk of bias was high because of contamination between groups, as 63% of control group participants accessed day care services separate from those offered within the intervention. No evidence suggested that centre-based day care, rather than no treatment (care at home), improved or worsened children's cognitive ability (Griffiths Mental Development Scale, standardised mean difference (SMD) 0.34, 95% confidence interval (CI) -0.01 to 0.69, 127 participants, 1 study, very low-quality evidence) or psychosocial development (parental report of abnormal development, risk ratio (RR) 1.21, 95% CI 0.25 to 5.78, 137 participants, 1 study, very low-quality evidence). No other measures of child intellectual or psychosocial development were reported in the included study. Moreover, no evidence indicated that centre-based day care, rather than no treatment (care at home), improved or worsened employment of parents, as measured by the number of mothers in full-time or part-time employment (RR 1.12, 95% CI 0.85 to 1.48, 114 participants, 1 study, very low-quality evidence) and maternal hours per week in paid employment (SMD 0.20, 95% -0.15 to 0.55, 127 participants, 1 study, very low-quality evidence) or household income above £200 per week (RR 0.86, 95% CI 0.57 to 1.29, 113 participants, 1 study, very low-quality evidence). This study did not report on long-term outcomes for children (high-school completion or income). AUTHORS' CONCLUSIONS: This review includes one trial that provides inconclusive evidence as regards the effects of centre-based day care for children younger than five years of age and their families in high-income countries. Robust guidance for parents, policymakers and other stakeholders on the effects of day care cannot currently be offered on the basis of evidence from randomised controlled trials. Some trials included co-interventions that are unlikely to be found in normal day care centres. Effectiveness studies of centre-based day care without these co-interventions are few, and the need for such studies is significant. Comparisons might include home visits or alternative day care arrangements that provide special attention to children from low-income families while exploring possible mechanisms of effect.

Centre-based day care for children younger than five years of age in low- and middle-income countries.

BACKGROUND: Because of poverty, children and families in low- and middle-income countries often face significant impediments to health and well-being. Centre-based day care services may influence the development of children and the economic situation of parents by providing good quality early childhood care and by freeing parents to participate in the labour force. OBJECTIVES: To assess the effects of centre-based day care without additional interventions (e.g. psychological or medical services, parent training) on the development, health and well-being of children and families in low- and middle-income countries (as defined by the World Bank 2011). SEARCH METHODS: In April 2014, we searched CENTRAL, Ovid MEDLINE, EMBASE, PsycINFO, ERIC and 16 other sources, including several World Health Organization (WHO) regional databases. We also searched two trials registers, websites of government and non-government agencies and reference lists of relevant studies. SELECTION CRITERIA: We included randomised and quasi-randomised controlled trials and prospective non-randomised studies with contemporaneous control groups and assessments both before and after intervention. We considered non-randomised controlled trials, as centre-based care in low- and middle-income countries is unlikely to be studied using randomised controlled trials (Higgins 2011). We included the following outcomes: child intellectual development, child psychosocial development, maternal and family outcomes and incidence of infectious diseases. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed risk of bias and extracted data from the single included study. MAIN RESULTS: Only one trial, involving 256 children, met the inclusion criteria for this review. This study was assessed as having high risk of bias because of non-random allocation, incomplete outcome data and insufficient control of confounding factors. Results from this study suggest that centre-based day care may have a positive effect on child cognitive ability compared with no treatment (care at home) (assessed using a modified version of the British Ability Scale-II (BAS-II) (standardised mean difference (SMD) 0.74, 95% confidence interval (CI) 0.48 to 1.00, 256 participants, 1 study, very low-quality evidence). This study did not measure other variables relevant to this review. AUTHORS' CONCLUSIONS: The single study included in this review provides limited evidence on the effects of centre-based day care for children younger than five years of age in low- and middle-income countries. This study was at high risk of bias and may have limited generalisability to other low- and middle-income countries. Many of the studies excluded from this review paired day care attendance with co-interventions that are unlikely to be provided in normal day care centres. Effectiveness studies on centre-based day care without these co-interventions are few, and the need for such studies is significant. In future studies, comparisons might include home visits or alternative day care arrangements.