Low intelligence predicts social conservatism
A recent paper  has aroused a lot of controversy. Complaints about the quality of the work sound as if they are coming from people who think of themselves as right wing and consider the paper a personal attack from someone they never mat who has never heard of them. It seems the controversy stems partly from careless use of language and careless reading by supporters and critics rather than poor research.
The paper concludes that lower cognitive abilities in childhood, measured as lower general intelligence: a parameter called g , predicts greater prejudice and that this is mediated through endorsement of “right wing” ideologies, that is ideologies based on social conservatism and right-Wing authoritarianism (RWA) , and groups characterised by low contact with other groups. Low abilities in abstract reasoning predicted greater levels of RWA and greater levels of prejudice against homosexuals.
Unfortunately the authors tend to conflate social conservatism and RWA, which in occurs in all parties, with political conservatism and rightwing ideologies in general. The modifiers “social” and “Authoriarianism” tend to be omitted. This has led to a certain amount of confusion and misreading of the paper.
Are Right Wingers unintelligent
It is fair to say however that observations tend to support the notion that supporters of parties generally considered to be right wing or even fascist tend not to be the sharpest knives in the drawer: Vox Pop interviews with members of Britain's Extreme Nationalist parties and the asinine pronunciations of many prominent American Republican politicians
The impressions given by observations of right wing activity in the media may be valid or they may be a result of sampling bias. The pronouncements of Republican leaders may be cynically uttered in order to gain the support of a constituency they secretly despise, for as Altemeyer has pointed out  Authoritarian FOLLOWERS are radically different from Authoritarian LEADERS. In particular the Leaders are generally anything but unintelligent especially when it comes to establishing social dominance
Common sense suggests that highly prejudiced people may be intelligent or not. The paper in question  seems to indicate that lower levels of childhood intelligence predict higher levels of prejudice, but it is clear that some intelligent people have exhibited high levels of prejudice. Given that childhood intelligence may be adversely affected by poor nutrition, which is predominantly experienced by the poor, and that poorer people form the bulk of the population it seems likely that a majority of highly prejudiced people would exhibit low g.
One of the paradoxes of British politics is that Labour voters tend to agree with Labour's economic policies and the Conservative's social policies. The conflict is less extreme in the Tory party where voters tend to support Tory economic policy AND Tory social policy, though various cultural and demographic changes seem to be driving Tory voters slowly towards Labours social policies.
Hodson and Busseri do not claim that Right-Wingers are stupid, they claim that people who have low cognitive abilities tend to show high levels of prejudice. Hodson and Busseri's observe that all predictive effects are independent of socioeconomic status and education. The second part of their claim is that people with low cognitive abilities tend to be attracted to right wing ideologies, that s socially conservative ideologies based on right wing authoritarianism.
In support of this it has been observed that the most prejudiced places in the UK are working mens clubs, which are generally white, male and patronised by people whose parents were in lower income groups and who left school as early as possible with a sigh of relief ( This attitude to education is not confined to low income groups). The patrons of these organisations tended to vote for “left wing” parties which they saw as furthering their own interests. They also tend to be intensely socially conservative: It was not, generally speaking upper class people who indulged in “Queer bashing! In the 1960s or who took part in the Race Riots of 1958 and later “Paki Bashing”.
At the other end of the political spectrum (which is more like a horseshoe) higher status and better education tend to characterise the Tory party, but are by no means limited to it, and the party ideology, at least at the grass roots is socially conservative and based on RWA: the Conservative party is widely regarded (at least from outside) as the stupid party, though some Tories delight in anti-intellectualism, and considers itself the party of law and order and traditional values.
In summary therefore the British Left contains many who are socially conservative and high in rightwing authoritarianism. The leaders of these parties are largely the opposite and and get the support of their constituency because of their economic policy. The British Right also contains many socially conservative right-wing authoritarians but a historical belief in freedom ( In practice only for the rich or deserving) muffles and masks the authoritarianism, though the leaders tend to be more like the grass roots.
Hodson and Busseri found the same sort of results when looking at US data. It would seem therefore that their findings are not a result of cultural factors though given the similarity between US and UK culture ( which are both basically White Anglo Saxon Protestant ) the research needs to be replicated across a wider range of cultures.
Some criticisms of the research
Some of the criticisms made of  suggest the authors feel the paper is aimed at them and appear to distort the original paper, for example a review  of a review by Monbiot starts by claiming that the paper asserted “people with conservative beliefs are likely to be of low intelligence” which appears to be a gross simplification of the claims in the paper. At the end they concede Monbiot's remark that
“There is plenty of research showing that low general intelligence in childhood predicts greater prejudice towards people of different ethnicity or sexuality in adulthood”
While saying the latter is that prejudice and stupidity are linked and that claim is something that does not need research!! The writer is therefore denying the link between Right Wing Authoritarianism, Social Conservatism and Prejudice towards outgroups, which seems to be well established, for example .
A less trivial criticism is . Briggs criticises the fact that the two datasets in  measure similar but different abilities but does not say how important that is, notes losses in the long term tracking of the participants, and wonders why Math and Reading test scores were not used (As I recall these tests would introduce cultural biases). Briggs, a professor of statistical science, criticises some of the questions used to establish authoritarianism, but seems unaware of the idea that some questions are designed to test for Authoritarianism and others are decoys.
The criticism in  Again ignores the difference between left and right wing social and economic policy and seems to be attacking first Monbiot's review , after conceding Monbiot‘s summary is a fair representation of the paper, then a a statement made by Monbiot which the writer claims, in my view unfairly, imputes conservative economic ideas to those of low intelligence who are racist (Hodson and Busseri explicitly say they focussed on socio cultural conservatism not economic conservatism): it seems that Monbiot is claiming that low g socially conservative right wing authoritarians are being manipulated and duped by a wealthy elite for their own ends. Monbiot's statement is indeed nothing to do with  but this does not invalidate the research there.
The writer's comment that the BNP is, apart from a taint of racism, a left wing party in many ways, just like the Nazi party in the 1930s and later.
Some criticisms of the original paper also mix criticism of Monbiot's review, and the criticism of the statistics by Briggs appears to show ignorance of psychological methodology, and attracted some adverse comments . Some critics validly pointed out that social conservatism and right wing authoritarianism are also characteristics of the British Labour party. Many also noted the link between stupidity and prejudice, while denying the link between prejudice and socially rightwing ideologies.
The controversy over this paper suggests the authors have struck a nerve with an electrified drill. The conclusions of the paper, that low cognitive abilities are related to higher levels of prejudice seem to be accepted. The notion that people with low cognitive abilities are attracted to ideologies that are socially conservative and authoritarian and that these ideologies mediate prejudice is challenged but the challenges seem to me to be based on misreadings of the paper.
In short and at the risk of over simplifying to be able to say this in plain language
The paper claims, if I understand it correctly that
Unintelligent people tend to be racist and homophobic.
Unintelligent people tend to be drawn to socially conservative and authoritarian ideologies
These ideologies tend to make unintelligent people more racist and homophobic.
Note the word “tend” in all these. There are highly intelligent people who are racist, homophobic and drawn to socially conservative and authoritarian ideologies. Reference  confounds the terms “unintelligent” and “stupid” but teasing out the difference between the two and working out how someone with excellent cognitive abilities can also be stupid is a problem for another time and place.
1] Bright Minds and Dark Attitudes: Lower Cognitive Ability Predicts Greater Prejudice Through Right-Wing Ideology and Low Intergroup Contact, Gordon Hodson and Michael A. Busseri Psychological Science XX(X) 1–9
 Altemeyer, B. (2006). The authoritarians. Cambridge.
 http://wmbriggs.com/blog/?p=5118 Criticism by Professor William Briggs
 http://www.forbes.com/sites/timworstall/2012/02/07/scientific-paper-conservatives-are-stoopid-so-there/ Scientific Paper: Conservatives Are Stoopid So There!
 http://www.guardian.co.uk/commentisfree/2012/feb/06/right-stupidity-spreads-enabled-polite-left The right's stupidity spreads, enabled by a too-polite left