Do positive psychology exercises work? A replication of Seligman et al. (2005).

OBJECTIVES: The current work replicated a landmark study conducted by Seligman and colleagues (2005) that demonstrated the long-term benefits of positive psychology exercises (PPEs). In the original study, two exercises administered over 1 week ("Three Good Things" and "Using your Signature Strengths in a New Way") were found to have long-lasting effects on depression and happiness (Seligman, Steen, Park, & Peterson, 2005).
DESIGN: These exercises were tested here using the same methodology except for improvements to the control condition, and the addition of a second "positive placebo" to isolate the common factor of accessing positive, self-relevant constructs. This component control design was meant to assess the effect of expectancies for success (expectancy control), as well the cognitive access of positive information about the self (positive placebo).
RESULTS: Repeated measures analyses showed that the PPEs led to lasting increases in happiness, as did the positive placebo. The PPEs did not exceed the control condition in producing changes in depression over time.
CONCLUSIONS: Brief, positive psychology interventions may boost happiness through a common factor involving the activation of positive, self-relevant information rather than through other specific mechanisms. Finally, the effects of PPEs on depression may be more modest than previously assumed.