- The study analyzed data from 418 participants who completed working memory training to investigate how individual difference factors influence training outcomes. - Age, country the study was conducted in, and baseline working memory abilities were found to predict how much participants' performance would improve over the course of training. However, gender, type of training (spatial vs. verbal), and level of supervision did not significantly impact outcomes. - Machine learning methods accurately classified 76% of participants as being in the top or bottom 50% for training gains, with age and baseline performance being particularly good predictors.