Psychologists take care to avoid bias in their investigations, for example making assumptions about differences between males and females (alpha bias) or overlooking differences between males and females (beta bias).

A study by researchers at Princeton University suggests the existence of a ‘bias blind spot’ that means people recognise that bias exists but assume they personally are not likely to be affected by it. As reported by Oliver Burkeman on his excellent blog, this meant that ‘Even when people acknowledge that what they are about to do is biased … they still are inclined to see their resulting decisions as objective.’

Does a famous name make this a better picture?

This is how the study was carried out: the researchers showed participants (a mix of Princeton students and others recruited online) a selection of 80 paintings, which they were asked to rate for artistic merit from 1 to 10. Half the group just saw the paintings, and the other half saw the paintings plus what were supposedly the names of the artists responsible.

In fact, the names were a mixture of famous artists and names chosen at random from a phone book. Those participants who saw the names exhibited a bias: they gave a higher ranking to works associated with names of famous artists. But even when the risk of bias was pointed out to them, these participants still rated their decisions as objective – while it was definitely likely that other people would be biased towards big names, no one thought it would affect them.