a strong trendp < 0.01
However there was a strong trend toward less training being more effective on overall cognition, with studies providing 20 h or less of training ( g = 0.41, 95% CI 0.14 to 0.68, p < 0.01, I 2 = 21.40%) being more effective than those that provided more than 20 hours ( g = 0.06, 95% CI -0.15 to 0.28, p = 0.55; Q = 3.80, df = 1, p = 0.05).