It’s been a big week. With a simple words, Barack Obama became the first black President of a country whose history has been so haunted by the spectre of racial prejudice. His election and inauguration are undoubtedly proud moments but they must not breed complacency. Things may be changing outwardly, but problems remain.

For a start, it goes without saying that many people, even the most liberal and left-wing among us, still harbour unconscious prejudices against members of other races. These “implicit biases” may be hidden, but their effects are often not. For example, a study published last year showed that unconscious biases can hold greater sway over a person’s voting decisions than their conscious, rational preferences.

Their influence becomes apparent