VEPs and contrast.
D000818:Animals; D005074:Evoked Potentials, Visual; D000882:Haplorhini; D006801:Humans; D009039:Motion Perception / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D014792:Visual Acuity