Cognitive function scores at before and after training in both groups.

Group comparison (two sample t-tests) of the pre-training scores revealed no significant difference in any measure of cognitive functions between the brain training group and the Tetris training group (p>0.10). Effect size estimates were calculated using Cohen’s d. d = 0.20 is regarded as small effect, d = 0.50 as medium effect, and d = 0.80 as large effect. Pre, pre-training; post, post-training; SD, standard deviation. Fluid intelligence was measured using Raven’s Advanced Progressive Matrices Test (RAPMT). Executive functions were measured using Wisconsin Card Sorting Test (WCST) and Stroop Task (ST). Working memory was measured using the Operation Span (OpS), letter–number sequence (LNS), arithmetic (Ari). Short-term memory was measured using the Digit Span (DS) and Spatial Span (SpS). Attention was measured using the Digit Cancellation Task (D-CAT) and Simple Reaction Time (SRT). Processing speed was measured using the Digit Symbol Coding (Cd) and Symbol Search. Visuo-spatial ability was measured using the Mental Rotation task (MT). Reading (verbal) ability was measured using the Japanese Reading Test (JART).