Figure 2: Comparison of the proposed variance entropy (VarEn) and sample entropy (SampEn) in discriminating the different perceptual conditions (Invisible versus Visible). Shown are the means and the standard errors of means of VarEn (left) and SampEn (right). As a result, the VarEn exhibits significant difference between two perceptual conditions ( , indicated by the sign “*’’), but the SampEn does not ( ).