ABSTRACT
Previous research has suggested that brief protocols based on acceptance and commitment therapy (ACT) are efficacious in improving elite chess players' performance without clinical problems. These promising results warranted the examination of the effect of longer ACT interventions with chess players suffering from emotional difficulties. This study advances in this direction by presenting two case studies of elite chess players experiencing anxiety disorders. Each participant was matched to a control participant with similar characteristics. The ACT interventions were conducted in 5 sessions and with occasional follow-ups during the following year. The primary dependent variable was an objective measure of chess performance (ELO Performance). Data analysis was conducted using the JZS+AR Bayesian hypothesis testing for single-case designs and the nonparametric Tau-U statistic. Control participants did not significantly improve their chess performance during the follow-up, but chess players who received the intervention showed significant increases in their performance. Both treated participants experienced clinically significant reductions in symptomatology and improved valued living after the intervention. This study provides empirical evidence regarding the potential benefit of applying ACT to improve chess performance in players with clinical problems (AU)
