Conference on Cognitive Computational Neuroscience

Our perceptual experiences are a result of a combination of sensory inputs and prior expectations. Specifically, expectations concerning the likelihood of a sensory stimulus have an impact on the perception of weaker stimuli. In this study, we aimed to investigate the effect of stimulus expectation on somatosensory perception and confidence, and examine the neural correlates of this expectation. Participants were required to report whether they felt a stimulus was present or absent and to rate their level of confidence in their decision. The probability of the stimulus was manipulated using cues that indicated either a 25% or 75% chance of a signal, which matched the actual probability of stimulus occurrence. Analysis of signal detection revealed that participants used a more conservative threshold to detect stimuli in the low probability condition. Additionally, participants displayed faster reaction times and higher confidence levels in expectation congruent trials. On a neural level, we observed higher prestimulus beta power in centro-parietal electrodes in the low probability condition. Our preliminary findings indicate that informative cues regarding stimulus probability alter the subjective threshold for detecting weak stimuli, and that this effect is reflected in a modulation of prestimulus beta power.