The numbers at the bottom denote the timing relative to the utterance. A negative value indicates a timing before the utterance, while a positive value signifies a timing after the utterance. Two kinds of monsters, black and red, were used alternately across trials so that participants would not lose interest. (a) An example of rare-event timing #-5. A monster emerged from a pipe, completed a specific action in 0.86s, and then disappeared back into the pipe. The next monster emerged after a 1-s interval. (b) An example of the rare-event timing #-6/ #-1. Two distinct actions were used for 1st rare event and 2nd rare event, respectively. (c) An example of the rare-event timing #-2/ # + 3.

https://doi.org/10.1371/journal.pone.0324557.g001