“…Other studies have applied the hidden Markov model (HMM), GMM, random forests (RFs), and other methods to cognitive biometric recognition based on ECG [ 38 , 158 , 160 ], PPG [ 161 ], SCG [ 89 , 162 ], PCG [ 79 , 163 , 164 ], EEG [ 52 , 83 , 165 ], and EDA signals [ 77 ]. Among them, HMMs, which are able to model raw sequential data and detect non-stationary changes, have been demonstrated to be efficient algorithms for classifying cognitive biological signals.…”