The influences behind our preferences are key. Johansson-Stenman and Martinsson argue that psychology experiments show evidence of a phenomenon referred to as “preference falsification”, which means that, in order to impress, we express a preference which we might not really have. A typical example is ordering an outlandishly expensive bottle of wine in a restaurant to impress your friends.

In their paper, published recently in the Journal of Economic Behavior and Organization, the pair also examine a new “falsification” fed by the need to be seen as “green”. The authors speculate that in our hunt to be politically correct, we may overstate our concern for the environment. A cycle then kicks in: we believe others also think it’s good to care about the environment, so we express a similar preference.

To test how much our choices are a product of the motivation to impress others, Johansson-Stenman and Martinsson anonymously surveyed a sample of Swedes about how much characteristics such as status value and environmental performance mattered when they were about to buy a car. They then asked a sample of car dealers the same question. The results indicate that dealers believe would-be buyers care more about status than they say.

The dealers also said that people care less about environmental performance than they claim.

Listen to conversations in the staffroom and you’ll get the impression that most people are concerned about the environment. In reality, they may just believe that others are more concerned and so fall into line. The desire to create a good impression can overshadow our true passions. In education, how many of us express an interest in subjects that we think will impress others rather than in those that really grab us?

Dr Raj Persaud is consultant psychiatrist at the Maudsley Hospital in south London and Gresham professor for public understanding of psychiatry. His latest book is The Motivated Mind (Bantam Press). Email: rajpersaud@tes.co.uk