"People with higher IQs are slow to detect large background movements because their brains filter out non-essential information, say US researchers."
All of our brains filter out and delete a great deal of information. This is an essential part of thinking and processing everything around us.
Your brain deletes, distorts and generalizes information. Everyone's mental filters are in tune to their own understanding and internal representation of the world (how one understands things and the model one has constructed in ones brain to represent his/her understanding of "reality").
A difference between people in this respect is in a better ability to filter out/delete more information that is less useful. All information that you are consciously aware of has already been filtered through your own mental filters before you are aware of it. We ultimately pay attention to what we believe is useful information. The difference between people in this regard is in discerning what is and isn't useful. One might notice a great deal of detail another doesn't. One might add a great deal of meaning where there isn't any and focus on useless information. For example, a meaningless event could be perceived by most to be just that and ignored where someone suffering from paranoid delusions might not only find significant meaning in it (create the meaning, significantly distorting the meaning/significance etc). That doesn't mean that a mentally disturbed person can't be extremely intelligent.
Furthermore, the data size is far too small to determine anything at all. Flipping a coin 58 times and getting heads 64% of the time doesn't tell you anything useful and even less when you understand that it takes many millions of coin flips to get to 50%.