Three Grades of Binocular Vision.
1: Grade I: _____________________ macular perception is the most elementary type of binocularity. It occurs when the visual cortex perceives separate stimuli to the two eyes at the same time and concerns itself essentially with the absence of suppression.
2: Grade II: It represents ___________ ___________ with some amplitude. Not only are the two images fused, but some effort is made to maintain this fusion in spite of difficulties. This it implies a motor response added to simple sensory fusion.
3: Grade III: In the highest type of binocularity, no only are the images of two eyes fused, but they are blended to produce a ____________________ effect. This involves a perceptual syntheses at a higher level.
4: These three graded are not necessarily mutually exclusive, since fusion in the periphery, even showing motor responses, may exist coincidentally with the total absence of simultaneous foveal perception.