It's something of a special day for social statistics geeks. Today is our Christmas, our Halloween and FA Cup final all rolled into one, as an annual package of data, trends and tables arrives overnight like our very own statistical Santa's stocking. The 30th British social attitudes (BSA) report is published this morning, documenting our changing national values, beliefs and shared opinions.

The survey, independently produced by NatCen Social Research, is a particularly useful guide to social trends. Unlike the raft of commercially commissioned opinion polls, which can be highly susceptible to influences and bias in wording and ordering of questions or vagaries of methodology – whether intentional or inadvertent – the BSA is broadly consistent year on year, asking people the same questions in the same way, to allow genuine trends to emerge.

What they show are, in most respects, unsurprising and familiar. Britain is becoming a more socially tolerant nation, particularly towards sex and relationships. In 1986, 64% of the British public believed that homosexuality was "always wrong". That has now fallen to 22%. Similar patterns apply to beliefs around gender roles, race and integration. We are also becoming markedly less religious. Only around half the population now declare any form of religious belief and that effect is strongest among so-called Wasps (white, Anglo-Saxon Protestants). Only 20% of the country now describes itself as Anglican.

All of these trends have been heading in the same direction since the mid-1980s. In one crucial respect though, Britons have been showing a broad decrease in tolerance since the turn of the century, and that is in our attitudes towards benefits claimants. This year there is an exception, and it is one that may prove significant on the political landscape. Since last year, and perhaps in stark contradiction to most people's expectations, attitudes towards benefit claimants have become strikingly more sympathetic. The difference in the 2012 findings is the largest single change on this scale since the survey began. Last year 62% felt that benefits were too high and discouraged work. This year that has dropped to 52%.

It is taken as a given among left-leaning observers that the coalition government has been engaged in something of a propaganda war against benefits claimants since 2010, ably assisted by political allies in the newspapers and other media. The language of "scroungers" and "shirkers", when contrasted with "hard-working families" carries an obvious agenda. Could it be that we are seeing a belated swing of the pendulum? Has Iain Duncan Smith pushed us too far, creating an attitudinal bounce? It is certainly credible when the most recent debates on benefits – notably around the bedroom tax and the painful, messy birth of universal credit – have not earned the government much sympathy. It could also be the case that after four or five years of economic slump and stagnation, ever more citizens have been forced to confront the harsh reality of life on benefits, either first hand or witnessing friends and family being ground through the mill.

I would urge caution. As the Guardian's Data Blog shows this morning, the graph on this question is what statisticians call, in technical jargon, a spiky little bugger. Rather than showing a smooth trend, attitudes on this topic seem remarkably susceptible to annual fluctuations. While the change between 2011 and 2012 was dramatic, so too was the hardening of attitudes in the other direction the year before. The longer-term trend remains depressing. In 2001 only 37% of people believed benefits were too high, exactly the same number as believed them to be too low. We've fallen far from those days while, in reality, life on benefits has become considerably more harsh.

The explanation, I suspect, is that asking whether benefits are too high or too low is an unusually difficult judgment to make. Whereas most of us will have broadly consistent positions on the rights and wrongs of homosexuality, for example, which might change a bit over decades but are unlikely to do so radically and quickly without a dramatic external cause (the Aids epidemic in the 1980s had such an effect, for the worse). But a judgment on the myriad economic complexities of costs of living, poverty traps and the value of wages, not to mention widespread confusion about true levels of benefits, make this particular question exceptionally sensitive to psychological influence and cognitive bias or, more bluntly, propaganda.

Those of us who despair of the vicious war of words being waged on the poor by the coalition government can take some comfort from these figures. At least for now, it would seem to be ineffective or even counter-productive. However, the fluctuations in the figures should also remind us of just how influential such political messages can be, and how important it remains to resist and counter the tide.