Myleene Klass's attack on the Mansion Tax has been met with cheering on the right and mockery on the left. Such tribalism overlooks a more important point - that the celebocracy which leads TV bosses to put people like Myleene onto political shows has a systematic pernicious effect.

An experiment (pdf) by James Andreoni and Justin Rao shows why. They got people to play simple dictator games in which one person could choose whether to share some money with another. They found that communication greatly influenced dictators' behaviour. When recipents were allowed to ask for money, dictators were much more generous than they were when nobody spoke. However, when dictators were allowed to speak, they were much meaner.

There are two things going on here. One is that if someone communicates with us, we tend to become more sympathetic towards them - even if that communication conveys no new information. The other is that, on the dictator's side, communication creates meanness, because a hollow apology substitutes for generous actions.

This implies that having celebrities appear on TV will increase our sympathy towards them. Because celebs are overwhelmingly likely to be rich, this increases our sympathy towards the 1%. This is an example of the mere exposure effect.

And, of course, the converse is true. Because the poor tend not to appear on such shows - especially in unedited form - their interests are under-weighted: out of sight, out of mind.

In fact, it might be worse than that. Experiments by Agne Kajackaite show that when people are ignorant of the potential consequences of their actions they tend to behave more selfishly. This suggests that excluding the poor from political discourse - how often do you see someone claming disability benefits on the Question Time panel? - can increase meanness towards them.

What's especially nasty about all this is that, in making us more favourable to the rich and less so to the poor, the media's celebocracy is exacerbating a longstanding tendency, identified by Adam Smith:

We frequently see the respectful attentions of the world more strongly directed towards the rich and the great, than towards the wise and the virtuous. We see frequently the vices and follies of the powerful much less despised than the poverty and weakness of the innocent. (Theory of Moral Sentiments,I.III.29: Smith was using "great" to mean eminent rather than worthy)

I don't say all this merely to deplore the celebocracy, but also to lament the state of the left. Its simple-minded tribalism - no doubt, it cheers when (say) Victoria Coren appears on such shows - prevents it from seeing how the media, perhaps unintentionally, help to shore up inequality.