Introduction: Electroencephalography makes it possible to record brain electrical activity at rest and during the performance of cognitive tasks. Objective: Determine whether brain activity analyzed as nonlinear dynamics remains stable during various time windows in basal, eyes closed conditions. Methods: Electroencephalographic records of 14 male university students were taken during two minutes. Hurst's index means (H) were then compared in time windows of 60, 30 and 10 seconds. Results: H index means are stable throughout the various time windows in the prefrontal, temporal and occipital regions. Conclusions: Electroencephalographic records in basal, eyes closed conditions are valid to compare experimental protocols for cognitive problem solving using the Hurst exponent in subjects from the sample as well as others of similar characteristics.