Errors in Chess Impair Subsequent Performance of Novices, But Not Experts. Evidence from One Million Games

Errors are an inevitable part of complex, real-world tasks and provide a window into how people monitor and regulate their behavior. In laboratory settings, mistakes reliably produce post-error slowing (PES)—a tendency to slow down in subsequent behavior—but the functional significance of PES and its impact on accuracy in naturalistic, self-paced environments remains unclear. Here, we analyze over one million online chess games to examine how errors affect subsequent decision-making. We find that players indeed slow down after an error. Additionally, their accuracy decreases by roughly 20%, revealing non-functional post-error adjustments. These effects are moderated by error severity, player ability, and response–stimulus interval, and persist even when more than 10 seconds elapse before the next move, challenging current theories of post-error behavior. Notably, expert players are less affected by post-error accuracy impairments, suggesting superior regulation of cognitive and motivational responses. Together, these findings indicate that in complex, self-paced settings, errors induce sustained changes in performance that extend beyond transient slowing, highlighting the importance of incorporating new motivational dynamics into models of post-error behavior.