Decision-making components and times revealed by the single-trial electro-encephalogram

Decision-making stems from a sequence of information processing steps between the choice onset and the response. Despite extensive research, uncertainty remains about the actual cognitive sequence involved in the reaction time. Using the hidden multivariate pattern method we modeled the single-trial electroencephalogram of participants performing a decision task as a sequence of an unknown number of events estimated as trial-recurrent, time-varying, stable topographies. We provide evidence for three events occurring during participant’s decision making, respectively representing encoding, attention orientation, and decision. This interpretation is supported by the observation that a targeted manipulation of stimulus intensity yields Piéron’s law in the interval between encoding and attention orientation, and Fechner’s law in the interval between attention orientation and decision. This final, decision-related, event is represented in the brain as a positive burst in parietal areas whose timing, amplitude and build-up predict the participants’ decision accuracy.