Low beta power reflects perceived temporal probabilities for uncertain future events

Humans tend to use elapsed time to increase the perceived probability that an impending event - e.g., the Go sign at a traffic light - will occur soon. This prompts faster reactions for longer waiting times (hazard rate effect). Which neural processes reflect instead the perceived probability of uncertain future events? We recorded behavioral and electroencephalographic (EEG) data while participants detected a target tone, rarely appearing at one of three successive positions of a repeating five-tone sequence with equal probability. Pre-stimulus oscillatory power in the low betaband range (Beta 1: 15-19 Hz) predicted the hazard rate of response times to the uncertain target, suggesting it encodes abstract estimates of a potential event onset. Informing participants about the targets equiprobable distribution endogenously suppressed the hazard rate of response times. Beta 1 power still predicted behavior, validating its role in contextually estimating temporal probabilities for uncertain future events.\n\nHighlightsO_LIElapsed time to an uncertain future target increases response speed (Hazard rate).\nC_LIO_LIPre-stimulus low beta-band (Beta 1: 15-19 Hz) power predicts the hazard rate to uncertain targets.\nC_LIO_LIBeta 1 power predicts response times even when elapsed time is factored out.\nC_LI\n\neTOC BlurbTavano et al. show that pre-stimulus low beta band (15-19 Hz) power predicts response times to an uncertain future target, even before its occurrence and under different prior knowledge conditions, suggesting it reflects contextual, subjective estimates of potential future events.