Figure 2

The Alternating Serial Reaction Time (ASRT) task. (a) Participants were placed in front of a screen and provided with a keyboard containing only four keys. Each key corresponded to one of four circles displayed horizontally on the screen. When a stimulus (a dog's head) appeared in any of the circles, the participant's task was to press the corresponding key as fast as possible. Once the correct key was pressed, a new stimulus appeared. The position of the stimulus alternated between predetermined pattern (P, yellow background) and random (R, red background) elements. (b) The predetermined pattern elements were part of an eight-element sequence, in which they alternated with random elements (e.g. 3-R-2-R-4-R-1R). The numbers represented the corresponding position on the screen in ascending order from left to right. Every trial was characterized as the third element of the underlying triplet (three consecutive trials). Due to the probabilistic sequence structure, this results in so-called high-probability triplets, which occur with a probability of 62.5%, and low-probability triplets, which occur with a probability of 37.5%⁷⁵. (b) One ASRT session (green background) consisted of 20 blocks (blue background), each containing 80 trials (yellow and red background), which was ten times the repetition of the eight-element sequence. Between blocks, participants could take self-paced breaks (purple background).