Do brain trainings apps improve executive functions? - An umbrella review of meta-analyses published on PsychINFO between January 2013 and March 2021

Executive functions and working memory are the cognitive foundations of self-regulation and, therefore, a key predictor of wide range of positive behavioural outcomes ranging from the quality of relationships to financial decision-making. A USD 3.2 billion cognitive training industry promises that practicing cognitive tasks on one’s smartphone or computer will strengthen these cognitive foundations and – by extension – improve a range of positive life outcomes. Previous meta-analyses have provided mixed results on an important pre-condition for such outcomes, however: robust performance improvements across different cognitive tasks following training. Several methodological and conceptual issues could play a role in disentangling the mixed results. These include: inclusion of passive control groups, failure to account for baseline differences between training and control groups, suboptimal handling of statistical dependence between effect sizes and inconsistencies in the definition of transfers between tasks and mapping between tasks and cognitive outcomes. This umbrella review systematically searched for meta-analyses investigating transfer effects of single-domain executive functions and working memory training and evaluated them in light of these issues. The search resulted in 5 eligible meta-analyses. All of them were affected by several of the mentioned issues. While the exact impact of the issues on the results of the included meta-analyses could not be assessed due to a lack of data, the effect sizes least affected by these issues provide evidence for small transfer effects between executive functions and general short-term memory (to which working memory belongs) (g 0.18), small (g 0.08) to large (g 0.6) transfer effects between narrow abilities of either and moderate (g = 0.35) to large (g = 0.62) transfer effects between task from the same narrow ability. Important avenues for further research synthesis are the collection of the data missing in this umbrella review and investigating moderators of the transfer effects between narrow abilities of executive functions and general short-term memory.