Question

You need two sharpened pencils or two thin knitting needles or two identical fine-tipped pens.

Hold a sharpened pencil in each fist horizontally (back of your hands facing the ceiling, with the tips facing each other). Keep your elbows bent so your hands are about 18" in front of you and at about eye level, spread your hands about 12 inches apart with the tips of the pencils facing each other. Close one eye and bring the pencil tips together until they touch. Now, repeat the exercise with both eyes open.

Explain what happened and WHY it happened

Answer 1

Answer.

In this exercise, it was much easier to bring the tips of the two pencils together with both the eyes opened compared to when only one eye was opened. This experiment can be said to demonstrate the working of depth perception which is the interpretation of the distance between two objects relative to the eyes. Depth perception is the ability to judge objects that are nearer or farther than others. And here Two eyes are better than one, especially when it comes to depth perception as the distance between the two eyes or retinal disparity in itself acts as a depth cue which helps to assess the distance between the tips of the two pencils as each eye looks at the image from a different angle.