Neuroelectric Form Color Concepts Revisited

Abstract

Samars (1994) comments focus upon computational errors, artifactual categorizations based upon linear dependence in Delta VEP marginal waveforms and their implications for conclusions draw in my previous paper on form-color categorizations with visual evoked potentials (Hudspeth, 1994). The Delta VEP marginal waveforms were not computed accurately in the previous paper. The current work provides properly computed Delta VEP orthogonal marginal waveform components (OMCs) which demonstrate form-color categorizations that closely approximate the results obtained from Principal Components Analysis (PCA) of the original four Delta VEP waveforms. However, the marginal Delta VEP waveforms should not be placed in the same analysis with the original Delta VEP waveforms as the results will contain the linear dependencies that Samar has outlined. This paper shows that the OMC waveforms and PCA eigenvectors for the original Delta VEP waveforms produce similar outcomes, although the OMC findings are less accurate in orthogonalizing form-color attributes than PCA. A similar analysis of random potential (RP) waveforms serve to demonstrate that orthogonal categories are not obtained with either OMC or PCA waveform components. The results show that the brain constructs orthogonal neuroelectric potentials to the specifications of an a priori form-color categories model.