From the description:
Researchers at the University of Rochester have found that a simple visual task can predict IQ. In the study, individuals watched video clips of black and white bars moving across a computer screen, the same clips you will see in this video. Their sole task was to identify which direction the bars drifted: to the right or to the left.
The images were presented in different sizes and the researchers measured how much time participants needed to be able to perceive the direction of the motion. Because the brain filters out background movement, it’s actually harder for most people to see movement in the larger images.
The study found that people with higher IQs were actually the worst at seeing movement in the large images, or, in other words, the best at filtering out distracting sensory signals. How people performed on this simple task turns out to be a very good predictor of their performance on a standardized intelligence test.