What do you base this belief on?
I'm aware of a study which circulated (picked up by the Guardian for example) a few years ago which suggests a correlation between the two, but that study has been ripped to shreds. Can you link to alternative sources?
I would suggest that there is a socially left-wing bias amongst those who attended higher education, because academia (the social sciences in particular) was overrun by the left-wing from the 60's onwards.
Once there is a strong political bias in education, its very difficult to break the self-perpetuating cycle of leftist bias. Especially when its reinforced by those students going out into other industries where they reinforce the narrative which feeds back into academia. In many universities its very hard to challenge the orthodoxy and succeed.
So I wouldn't associate right-wing views with lesser intelligence. Perhaps in general there is an educational link, but there are many highly intelligent people who endorse right-wing views.
Given that you've no concept of what is far-right, I find it difficult to believe you've any concept of what is 'central left (sic)'.
There are endless studies on the matter, e.g.
http://www.sciencedirect.com/science/article/pii/S0160289609000051
But it is more complex than a simple linear relationship. As elmarko pointed out, lower intelligence is more strongly associated with social conservatism than economic. And there are a load of other factors to consider, e.g it is believed that extreme left or right political views tend to correlate with lower intelligence because the far extremes tend to be extremes rigid, e.g. UKIP.
Then there are things like conservatism is negatively correlated with education and education is positively correlated with intelligence. If lower intelligent demographics were educated to the same standards then there may be no or reduced political differences.
One of the important factors within higher education demographics, e.g. those who attended university, is that they are shown a much broader political landscape, exposed to different opinions and viewpoints. People that leave school at 16 because of failed grades, live with their parents for much longer, never leave their home town, stay with their same school friends who also didn't go off to university are more isolated and therefore more likely to maintain the same social-political beliefs of their peer group and especially their parents.
You then have the issue that in most western countries the main political parties are all center right, e.g. Tories and Labour in the UK, so it can be hard to get true representative samples.
There are also cultural differences, e.g. I believe the effect size is much bigger in the US, with the socially conservative tea party members bringing down the republican mean.