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Projection of Left and Right Visual Fields and the Two Eyes onto the Right and Left Cerebral Hemispheres

The right visual field maps onto the left hemisphere, and the left visual field maps onto the right hemisphere. But each eye connects to both hemispheres in humans, monkeys, cats, and all other animals that have eyes facing the front. Figure 1 shows that each eye sees at least part of both left and right visual fields.

Figure 1. Projection of visual field onto visual cortex. Both eyes get images from both visual fields.

Figure 1 also shows how the left side of each eye gets the image from right visual field and sends neural signals to the left hemisphere. The right side of each eye gets the image from the left visual field and sends neural signals to the right hemisphere. Thus, both eyes take in parts of both visual fields.

You can see this for yourself by fixating on (~looking straight at) your thumb held straight out in front of you. Your thumb locates the division point between the left and the right visual field: everything to the left of the thumb, goes to the right hemisphere, and everything to its right goes to the left hemisphere. Now close one eye: you will still see things on both sides of the thumb (both visual fields) through the one eye that remains open.