An introductory text reads: What we see, hear, taste, touch, smell, and feel may seem very real, but perceptions are not always accurate representations of reality. The brain’s perceptual systems are prone to errors and distortions. Studying illusions, like those shown here, we can detect and better understand the brain’s misinterpretations of visual input.
A photo shows a landscape with a larger moon and trees. Text reads: Have you ever noticed that the moon can appear much larger when it’s on the horizon versus high in the sky? Don’t let perceptual errors trump logic: You know the moon does not change size! Researchers have yet to agree upon a definitive explanation for this illusion, but many suspect it has something to do with the surrounding environment (Weidner et al, 2014). Seeing the moon along with trees and other objects at different distances may influence our perception of the moon’s size.
The first illustration titled Ponzo illusion shows a railway track. The tack narrows as it moves away from the viewer. Two horizontal lines are marked on the track. The line ‘a’ is drawn farther away from the line b. Both the ends of line extend outside the track and line b is inside the track. Text reads: Which of the two red bars is longer? Neither! They are identical. When you see two lines converging in the distance, your brain perceives them as getting farther away. Line A appears farther away. It seems longer because the images of the two lines projected onto the retina are the same size, but we interpret the farther line as being bigger. The Ponzo illusion demonstrates how we judge an object’s size based on its context.
The second illustration titled Ames room illusion shows 2 perspectives of a single photo. The first photo shows a rectangular room with a man standing in the left corner and a woman standing in the right corner. The man looks small and the woman looks big. The second photo shows a trapezoidal room. The floor where the woman stands is above the actual ground level and where the man stands is at ground level.
Text reads: Would you believe that the two people in this room (photo far left) are approximately the same height? The woman on the right appears about twice as big, because the room isn’t rectangular! The Ames room is actually trapezoidal (see diagram), but, as the photo shows, this is not apparent when it is viewed through a peephole with one eye.
The third illustration titled The Shepard Tables illusion shows 2 tables labeled a and b. Text reads: Look carefully at these two tables. Is one longer than the other? If you compare their measurements with your fingers or a piece of paper, you will see that both the length and width are identical. Table a shows side view of a rectangle whose back edge is long compared to other width. The length of the rectangle is long. Table b shows front view of a rectangle whose back edge is longer than the front edge. The length of the rectangle is small. The back edge of table a reads: The brain sees table (a) and thinks the back edge is farther away than table (b), and thus table (a) appears narrower and longer than table (b).