This project shows the Muller-Lyer illusion. The illusion shows two lines, one ending with arrows and the other with tails. When the lines are the same length, the line ending with tails looks longer than the line ending with arrows. In this interactive version, your job is to adjust the length of the lower green line, using the left and right arrow keys, until it looks like the lines are the same length. At that point, it'll be revealed to you the actual lengths of the lines in the image, and how much effect the illusion had on you! This illusion was developed in 1889, and has been used ever since to demonstrate the complexity of the human visual system! Press "space" to continue. You can use the options to force the lines to be either parallel or flat. Press the green flag to play again!
Use the left and right arrow keys to adjust the length of the lower line until both lines appear the be the same length. See: https://en.wikipedia.org/wiki/M%C3%BCller-Lyer_illusion for more about the illusion itself!
