Belief perseverance has been demonstrated by various studies, for example, an investigation in which two groups, one in favour of capital punishment and the other opposed to it, were presented with two purportedly-new research studies: the findings of one supported its deterrent efficacy and the other refuted such efficacy. The body of evidence presented was therefore mixed. The subjects reacted approvingly to the study results which appeared to support their initial beliefs about – either in favour of or opposing – capital punishment, but discounted the results of the study which contradicted them. Disturbingly, rather than tempering or provoking any reappraisal of their beliefs, the subjects instead responded to the contrary evidence by hardening their already-held position on the issue!

Two strategies for moderating this bias concern becoming more aware of our own cognitive processes: we should remind ourselves to think carefully about how we evaluate evidence regarding claims we distinctly favour (or oppose) such that we make conscious efforts against exaggerating evidence which appears to bear out our viewpoint – positive or negative – while taking pains to guard against any tendency to unjustifiably discount evidence seeming to support alternative conclusions or hypotheses. Secondly, we should actively counter-argue our current beliefs, especially when there is controversy about the issue(s), which involves asking oneself in what ways one’s beliefs might be wrong. To do this a technique which can be useful is to consider the opposite – giving conscientious consideration to credible alternative views (and thinking of one’s preferred view as truly in doubt). When people are asked to seriously take on the idea that the opposite of their beliefs might be true, research findings show they are less likely to succumb to belief perseverance.

As implied above, one very pernicious consequence of this phenomenon is that once a belief is incorporated into our framework of beliefs it will usually require more compelling evidence to change it – and especially to reject or overturn it – than it did to have the belief accepted in the first place. When confronted with a discrepancy between belief and facts, we should strive to resist any inclination to unthinkingly assume that our beliefs are right and the facts somehow ‘wrong’. (This doesn’t mean that we should be unquestioning about information presented to us.)

Our attachment to particular beliefs may be so strong that we see them as a vital and indispensable component of our very identity. Unfortunately, the more invested we feel in our beliefs, the greater will be our tendency to protect them – so when these beliefs are challenged, if we don’t make assiduous efforts to prevent it, we risk becoming even more immersed in beliefs which may be mistaken.

† (or the way in which this evidence was previously interpreted to justify the belief).