From Vandekerckhove, Matzke, and Wagenmakers
the lexical decision task, a task in which participants have to decide quickly whether a letter string is an existing word (e.g., sunscreen) or not (e.g., tolphin). When repeatedly presented with the same stimuli, participants show a power law decrease in their mean response latencies; in fact, they show a power law decrease in the entire response time distribution, that is, both the fast responses and the slow responses speed up with practice according to a power law (Logan, 1992).
Lei Ma (2020). 'Lexical Decision Task', Intelligence, 11 April. Available at: https://intelligence.leima.is/bio-intelligence/cognition/lexical-descion-task/.