[Assistant Professor Jack Glaser of the University of California, Berkeley's Goldman School of Public Policy] acknowledged that the team’s exclusive assessment of the psychological motivations of political conservatism might be viewed as a partisan exercise. However, he said, there is a host of information available about conservatism, but not about liberalism.
The researchers conceded cases of left-wing ideologues, such as Stalin, Khrushchev or Castro, who, once in power, steadfastly resisted change, allegedly in the name of egalitarianism.
Yet, they noted that some of these figures might be considered politically conservative in the context of the systems that they defended. The researchers noted that Stalin, for example, was concerned about defending and preserving the existing Soviet system.
At least one of the authors, John Jost, has his own web page at NYU, where he cites this paper as one of many pieces of scholarly research and authorship (http://www.psych.nyu.edu/jost/). His research summary does not give me the impression that he particularly has an axe to grind with Conservatism.
I strongly recommend reading the Guardian article and the original Berkeley press release, and then forming your own opinion.
In light of all of the above, though, I’d take the work described in the article seriously, and think that Conservatives should do some soul searching. On the other hand, I’ll be interested in seeing their research article on Liberalism. :)