Table 2.
Risk of Bias for Each Study
| Reference | Random sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcome assessors | Incomplete outcome data | Selective reporting | Baseline imbalance | Differential attrition |
|---|---|---|---|---|---|---|---|---|
| Ashar et al., 2016 | Low | Unclear | Low | Unclear | Low | Low | Unclear | High |
| Asuero et al., 2014 | Unclear | Unclear | Unclear | Unclear | Unclear | Low | Low | Low |
| Condon et al., 2013 | Unclear | Unclear | Low | Low | Unclear | Low | Unclear | Unclear |
| Flook et al., 2015 | Unclear | Unclear | Unclear | High | Unclear | Low | Low | Low |
| He et al., 2015 | Low | Unclear | Unclear | Unclear | High | Low | Low | Unclear |
| Hutcherson et al., 2008 | Unclear | Unclear | Low | Unclear | Unclear | Low | Unclear | Low |
| Jazaierir et al., 2013 | Low | Unclear | High | Unclear | Low | Low | Low | Low |
| Kang et al., 2014 | Unclear | Unclear | Low | Unclear | Low | Low | Low | Low |
| Kang et al., 2015 | Unclear | Unclear | Low | Unclear | Low | Low | Low | Low |
| Keefe 1979 | Low | Unclear | Low | Unclear | Low | Low | Low | Low |
| Kemeny et al., 2012 | Low | Unclear | Low | Low | Low | Low | Low | Low |
| Kok et al., 2013 | Unclear | Unclear | High | Unclear | Low | Low | Low | High |
| Logie et al., 2015 | Unclear | Unclear | Low | Unclear | Low | Low | High | Low |
| Mascaro et al., 2013 | Unclear | Unclear | Low | Unclear | Low | Low | Low | Low |
| Oman et al., 2010 | Unclear | Unclear | High | Unclear | Low | Low | Low | Low |
| Pearl et al., 1994 | Unclear | Unclear | Unclear | Unclear | High | Low | Unclear | Unclear |
| Poehlmann-Tynan et al., 2016 | Unclear | Unclear | Low | Low | High | Low | Low | Unclear |
| Rosenberg et al., 2015 | Unclear | Unclear | High | Low | Low | Low | Low | Low |
| Schonert-Reichl et al., 2015 | Low | Low | Low | Low | Low | Low | High | Low |
| Shapiro et al., 1998 | Unclear | Unclear | Low | Low | Unclear | Low | Low | Unclear |
| Shapiro et al., 2010 | Unclear | Unclear | Low | Unclear | Low | Low | Low | Low |
| Taylor et al., 2015 | Unclear | Unclear | Unclear | Unclear | Unclear | Low | High | Unclear |
| Velasquez et al, 2015 | Unclear | Unclear | Low | Unclear | Unclear | High | Low | High |
| Wallmark et al., 2013 | Low | Unclear | High | Unclear | Low | High | High | Low |
| Weng et al., 2013 | Unclear | Unclear | Low | Unclear | Low | Low | Low | Low |
| Weng et al., 2015 | Unclear | Unclear | Low | Unclear | Low | Low | Low | Low |
Note. Performance bias (blinding of participants and personnel) was considered low if (1) there was an active control group and participants were not likely to know which was the true intervention; (2) there was an inactive control group (e.g., wait-list control) but participants were not aware that the intent of the intervention was to increase prosocial outcomes (e.g., the intervention was framed as stress reduction); or (3) there was an inactive control group and participants were aware of the purpose of the intervention, but outcomes were measured in terms of implicit attitudes or behaviors based on deception. Performance bias was considered high when there was an inactive control group, participants were aware of the intent of the intervention, and outcomes were self-reported. Performance bias was considered unclear when it was unclear whether participants knew the intent of the intervention (e.g., when the authors did not report how the study was advertised or presented to participants).