Leaning lines
Do you think that the long black lines in this image are parallel to one another? Do they all travel in the same direction or are they tilting different ways? This illusion is all down to the multiple short lines intersecting the long ones. While the long diagonal lines appear to tilt in different directions, they actually all cross the picture at exactly the same angle. How can the addition of these smaller lines distort the picture so drastically? The science behind this illusion is all about how the brain processes an angle. One theory is that our brains tend to perceive small acute angles as being smaller than they really are, while we also overestimate the size of larger obtuse angles. In distorting the angle created between the long and short lines, the edges of the longer lines become warped in our heads. Each long line appears to tilt in the direction of the smaller angle. These angles are more likely to be misinterpreted when viewed on lines which are neither horizontal nor vertical, which is why they are positioned diagonally.