The most descriptive surprise definition for brain’s EEG response to visual and auditory oddball tasks

The human brain continuously tries to predict sensory input in order to prepare for responding to new events. The brain develops a model for the incoming sensory information and updates it as new inputs arrive. It is hypothesized that the brain deduces a distribution for the input which is made more accurate with new observations. A notable question is how the brain perceives and reacts to new information. The oddball paradigm task is a simple experiment that can reveal the brain’s ability in predicting the incoming input. We analyzed the EEG response of the brain recorded during oddball visual and auditory tasks in order to characterize its response to surprising instances embedded in a string of input stimuli. Different definitions of surprise were evaluated for their ability to describe the brain’s response. The information-theoretic Shannon surprise was found to serve as the best model to fit the experimental EEG data.