In this study participants had to play a simple game based on making numerical estimations in attempt to improve their decision making skills. After nine sessions participants did improve in accuracy of simple every-day estimation tasks and were more confident in their judgment.
Sobkow, A., Fulawka, K., Tomczak, P., Zjawiony, P., Traczyk, J. Does mental number line training work? The effects of cognitive training on real-life mathematics, numeracy and decision making. Journal of Experimental Psychology: Applied