TY - JOUR T1 - Perceiving structure in unstructured stimuli: Implicitly acquired prior knowledge impacts the processing of unpredictable transitional probabilities JF - bioRxiv DO - 10.1101/738419 SP - 738419 AU - Andrea Kóbor AU - Kata Horváth AU - Zsófia Kardos AU - Dezso Nemeth AU - Karolina Janacsek Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/08/19/738419.abstract N2 - It is still unclear how implicit prior knowledge is involved in the extraction of the statistical structure underlying sensory input. Therefore, this study investigated whether the implicit knowledge on 2nd order transitional probabilities characterizing a stream of visual stimuli impacts the processing of unpredictable transitional probabilities embedded in a similar input stream. Young adults (N = 50) performed a four-choice reaction time (RT) task that consisted of structured and unstructured blocks. In the structured blocks, an alternating regularity repeated, yielding more probable and less probable short-range non-adjacent transitional probabilities. In the unstructured blocks, without the presence of the alternating regularity, the unique combinations of the short-range transitional probabilities occurred with equal probability, therefore, they were unpredictable. All task blocks were visually identical at the surface level. While one group of the participants completed first the structured blocks followed by the unstructured blocks, this was reversed in the other group. Participants completing first the structured blocks showed faster RTs to more probable than to less probable short-range transitional probabilities in both the structured and unstructured blocks, indicating the transfer of prior knowledge. In contrast, participants completing first the unstructured blocks showed this RT effect only in the structured blocks. These results overall suggest that, during the learning of serial dependence, the implicitly acquired prior knowledge on a transitional probability structure influences the processing of unstructured stimuli through the formation of internal models. ER -