On the left you see an image of a cute kid, and on the right you see how people look at it, if given a few moments to stare. The squiggly lines are the work of a pioneer in vision research, and he had even more interesting squiggles to show us.
Al'fred Luk'yanovich Yarbus is referred to, for sanity's sake, simply as "Yarbus" in the papers that cite his work and in the books that describe the influence of his research. There are a lot of both of them. Yarbus was one of the earliest scientists to track eye movements when people viewed images.
Born to Polish parents in Russia, in 1914, Yarbus was thrust into a situation that promised an adventurous (or short) life. He studied physics and worked as an engineer before being whisked off for four years to fight in World War II, fighting the Japanese. During the war, Yarbus and his wife had a daughter who went on to be a successful artist. He shared his daughter's fascination with the visual. Though working after the war at a crystallography research lab, got his PhD in visual illusions. He became fascinated with how the eye sees a picture.
His interest in human behavior and his experience in engineering combined. Working with a colleague, he developed one of the first eye-tracking machines. The use of eye-tracking is now part of nearly every experiment involving vision. People don't always admit to the things they stare at. Yarbus found out what held people's gaze.
One of his most famous studies proved a relatively simple idea: two people with different goals look at different things, even if they're both seeing the same picture. Yarbus studied this by showing his research participants a famous painting; Ilya Repin's An Unexpected Visitor. The painting was well-known since its debut, in 1884, but Yarbus wasn't trying for novelty. Before he had people look at the painting, he gave them different goals. Unsurprisingly, this led to different patterns of eye movement. Below, you can see how people with different instructions assessed the same piece of art.
In 1965, Yarbus published the results of his experiment in a book, Eye Movements and Vision. It was translated to English in 1967, and has been a classic in multiple countries ever since.