People with higher IQs are slow to detect large background movements because their brains filter out non-essential information, say US researchers. Instead, they are good at detecting small moving objects.
The findings come in a study of 53 people given a simple, visual test in Current Biology. The results could help scientists understand what makes a brain more efficient and more intelligent.
In the study, individuals watched short video clips of black and white bars moving across a computer screen. Some clips were small and filled only the centre of the screen, while others filled the whole screen. The participants' sole task was to identify in which direction the bars were drifting - to the right or to the left.
Participants also took a standardised intelligence test. The results showed that people with higher IQ scores were faster at noticing the movement of the bars when observing the smallest image - but they were slower at detecting movement in the larger images.
Michael Melnick of the University of Rochester, who was part of the research team said the results were very clear.
"From previous research, we expected that all participants would be worse at detecting the movement of large images, but high IQ individuals were much, much worse.
The authors explain that in most scenarios, background movement is less important than small moving objects in the foreground, for example driving a car, walking down a hall or moving your eyes across the room.