In 2013, an angular velocity based brain injury criterion BrIC, has been proposed by the National Highway Traffic Safety Administration (NHTSA) for consumer vehicle safety assessment tests. In this study, the effect of duration of angular velocities on the predictor’s precision was examined. The cumulative strain damage measure (CSDM) and the maximum principal strain were calculated with the data of 445 anthropomorphic test device (ATD) in various vehicle crash tests conducted by NHTSA and the Insurance Institute for Highway Safety (IIHS) using the Simulated Injury Monitor (SIMon ver. 4.0), a finite element model of human brain developed by NHTSA’s research institute. The test dataset which composed of different risk levels of brain injury CSDM, MPS, BrIC and their corresponding angular velocities and durations were classified using Self-Organizing Maps (SOMs) combined with hierarchical clustering. The result showed that the differences of the probability of the risks between CSDM, MPS and the corresponding BrICs might be larger when the peak values of angular velocities were higher and the corresponding time durations were shorter.