This "study" appears to be less of an intelligence test than a simple vision test. It is generally true that people get more conservative as they get older. And people's vision generally gets worse as they get older. Therefore, a slight skew that makes conservatives "fail" this test more often.

Maybe someone can do a scientific test on liberals' apparant need to turn all their political opinions into "science" - perhaps in order to close down debate.

The stimuli used in these studies are always very large to ensure that individuals can see them clearly. I very much doubt that differences in vision account for their results. Other confounding factor no doubt exist, but I do not think this is one of them

What makes you think the study hasn't balanced the age of the participants?

Or do you just throw out blanket accusations with no facts to back them up..... just like a conservative.