Learning a skill with the expectation of teaching it impairs the skill's execution under psychological pressure

When practicing a motor skill, learners who are expecting to teach it to another person exhibit superior gains in skill execution and declarative knowledge. Since skills acquired with large gains in declarative knowledge are highly susceptible to decrement under psychological pressure, it is possible the advantage of expecting to teach is lost when performing the learned skill under pressure. To test this hypothesis, we had 40 participants practice golf putting with the expectation of teaching (teach group) and 42 participants practice with the expectation of being tested (test group). The next day, all participants performed low- and high-pressure posttests. The teach group outperformed the test group under low pressure but not high pressure, where the teach group's performance declined to that of the test group. Further, the teach group reported using more declarative knowledge during the posttests than the test group, but declarative knowledge use did not mediate the performance decline from low- to high-pressure posttest. Taken together, results suggest expecting to teach benefits skill learning, but this advantage is lost when performing the skill under high pressure. However, whether skill breakdown under high pressure is caused by an increase in declarative knowledge use remains an open question.