Each card shows what the study actually found, and its limits.
Moderate evidence
An experimental study in which participants keeping weekly gratitude notes rated their lives more positively.
Limitation: Student sample; later studies found smaller effects.
Emmons, R. A., McCullough, M. E. (2003). Counting blessings versus burdens: an experimental investigation of gratitude and subjective well-being in daily life. Journal of Personality and Social Psychology. doi:10.1037/0022-3514.84.2.377
Strong evidence
A meta-analysis of 94 tests finding that concrete "if this happens, I will do that" intentions are linked with goal attainment at a medium to large level.
Limitation: The effect belongs to concrete if-then plans; the same evidence does not exist for general intention statements.
Gollwitzer, P. M., Sheeran, P. (2006). Implementation intentions and goal achievement: a meta-analysis of effects and processes. Advances in Experimental Social Psychology. doi:10.1016/S0065-2601(06)38002-1
Strong evidence
A meta-analysis of 27 studies linking gratitude practices with a small decrease in anxiety and depressive symptoms.
Limitation: The effect is small and shrinks further against other active practices.
Cregg, D. R., Cheavens, J. S. (2021). Gratitude interventions: effective self-help? A meta-analysis of the impact on symptoms of depression and anxiety. Journal of Happiness Studies. doi:10.1007/s10902-020-00236-6
Strong evidence
A meta-analysis of 146 randomized studies finding a small but positive effect of writing about feelings.
Limitation: The effect is very small and varies between people.
Frattaroli, J. (2006). Experimental disclosure and its moderators: a meta-analysis. Psychological Bulletin. doi:10.1037/0033-2909.132.6.823
Strong evidence
A meta-analysis linking loneliness and social isolation with worse long-term health outcomes.
Limitation: Observational data; it does not show cause and effect. Evidence for online peer support is still limited.
Holt-Lunstad, J., Smith, T. B., Baker, M., Harris, T., Stephenson, D. (2015). Loneliness and social isolation as risk factors for mortality: a meta-analytic review. Perspectives on Psychological Science. doi:10.1177/1745691614568352