PsychophysicsSensory ThresholdsSensory AidsDiscrimination (Psychology)Photic StimulationRefractory Period, PsychologicalVisual PerceptionDifferential ThresholdForm PerceptionMotion PerceptionContrast SensitivityBlood VolumePattern Recognition, VisualVision, LowModels, PsychologicalDepth PerceptionSignal Detection, PsychologicalReadingPerceptual MaskingVisual CortexColor PerceptionModels, NeurologicalVision TestsFixation, OcularOrientationAuditory PerceptionPerceptionMagnetic Resonance ImagingVisual PathwaysVisual FieldsVision, OcularVision DisparityCuesAcoustic StimulationVision, BinocularElectroretinographyDiscrimination LearningPlasma VolumeReaction TimeAttentionStroke VolumeVisual Field TestsLung Volume MeasurementsVisual AcuityBrain MappingTime FactorsErythrocyte VolumePsychomotor PerformanceBlood Volume DeterminationForced Expiratory VolumeNeuronsImaging, Three-DimensionalOrgan SizeResidual VolumeImage Processing, Computer-Assisted