Objects off the horopter can produce diplopia or suppression unless fusion is achieved because they stimulate non-corresponding retinal points. Which statement best reflects this idea?

Objects off the horopter can produce diplopia or suppression unless fusion is achieved because they stimulate non-corresponding retinal points. Which statement best reflects this idea?

• A. They will always produce fusion automatically.
• B. They may produce diplopia or suppression.
• C. They produce color changes.
• D. They do not affect perception.

Answer: (B)

Objects that lie off the horopter create retinal disparity because each eye is receiving a different image of the scene. The brain normally fuses the two eyes’ inputs into a single image with depth, but when the images come from non-corresponding retinal points, fusion is not guaranteed. If the disparity is small enough or the system can compensate, you still see a single image with depth. If fusion can’t be achieved, the visual system may produce diplopia (two separate images) or suppress one of the images to avoid double vision. This is why the correct statement is that off-horopter objects may produce diplopia or suppression. Color changes aren’t a direct consequence of disparity, and perception is not always unaffected—disparity can disrupt single-binocular vision when fusion fails.

Objects that lie off the horopter create retinal disparity because each eye is receiving a different image of the scene. The brain normally fuses the two eyes’ inputs into a single image with depth, but when the images come from non-corresponding retinal points, fusion is not guaranteed. If the disparity is small enough or the system can compensate, you still see a single image with depth. If fusion can’t be achieved, the visual system may produce diplopia (two separate images) or suppress one of the images to avoid double vision. This is why the correct statement is that off-horopter objects may produce diplopia or suppression. Color changes aren’t a direct consequence of disparity, and perception is not always unaffected—disparity can disrupt single-binocular vision when fusion fails.