Serial and joint processing of conjunctive predictions

ABSTRACT When two jointly presented cues predict different outcomes, people respond faster to the conjunction/overlap of outcomes. Two explanations exist. In the joint account, people prioritize conjunction. In the serial account, people process cues serially and incidentally respond faster to conjunction. We tested these accounts in three experiments using novel web based attention-tracking tools. Participants learned colour-location associations where colorus predicted target locations (Experiment 1). Afterward, two cues appeared jointly and targets followed randomly. Exploratory data showed participants initially prioritized locations consistent with the conjunction, shifting later. Experiment 2 presented complex color-category associations during exposure. Upon seeing joint cues, participants' responses indicated both serial and joint processing. Experiment 3, with imperfect cue-outcome associations during exposure, surprisingly showed robust conjunctive predictions, likely because people expected exceptions to their predictions. Overall, strong learning led to spontaneous conjunctive predictions, but there were quick shifts to alternatives like serial processing when people were not expecting exceptions.