Multivariate vectorial analysis of the visual evoked response

Principal component analysis of a set of V.E.R.s yields vectorial representations of the responses in a diagram of a reduced dimensionality. In a vectorial diagram the responses can be resolved into components, associated with the aspects of the stimulus modulation and the state of the visual system. The appearance of a scotopic and a photopic component is demonstrated. In another experiment small modulations of luminance and color evoked the responses. The distorting effect of a type of non-linearity of the visual system, that is latency variation of the responses and the components, is discussed and demonstrated.