High IQ means intelligent information filtering
You have to be able to process relevant information quickly whilst suppressing or filtering out less relevant, distracting information.
"High IQ people do really well when the image is small, but they struggle even more than lower IQ individuals when the object is large and more background-like," explained Dr Tadin. "What this tells is with regards to motion perception is that the visual system of high IQ individuals is automatically biased to process smaller moving objects and to ignore background movement."
Via Howard Rheingold, Ken Morrison, Miloš Bajčetić