Rules are often stated in a negated manner (“no trespassing”) rather than in an affirmative manner (“stay in your lane”). Here, we build on classic research on negation processing and, using a finger‐tracking design on a touchscreen, we show that following negated rather than affirmative rules is harder as indicated by multiple performance measures. Moreover, our results indicate that practice has a surprisingly limited effect on negated rules, which are implemented more quickly with training, but this effect comes at the (...) expense of reduced efficiency. Only affirmative rules are thus put into action efficiently, highlighting the importance of tailoring how rules are communicated to the peculiarities of the human mind. (shrink)