Task novelty and participants. Regarding experience, bothnovelty of performed task and type of participants were tested. Novelty of the task was a marginally significant moderator: novel, d ¼ 0.73, 95% CI (0.47, 1.00), tended to exceed welllearned, d ¼ .41, 95% CI (0.31, 0.50), tasks. According to learning principles (Schmidt & Bjork, 1992) individuals are more likely to show greater improvement at the early stages of learning than at the later stages. Accordingly, the use of mental strategies was expected to be more effective when novel tasks were used. Nevertheless, it is worth noting that the difference was not substantially in favor of the novel tasks and that the effect size was also meaningful for well-learned tasks, thus suggesting that self-talk can be effective and useful in later stages of skill acquisition and performance enhancement.