What do your idiosyncrasies say about the kind of person you are? Is it possible for psychologists to predict your reactions without ever meeting you? The behaviour of 100 volunteers is observed through a series of tests, with the professionals then fitting them into their distinct personality types. Viewers can get to know themselves better by joining in online at www.bbc.co.uk/science or via their TV handset and see to what extent they agree with the experts. With Nick Knowles. Director Daniel Adamson ; Executive producer Viv McGrath Do the test yourself: page 28