Those wishing to become a Train Driver in the UK are required to pass a series of psychometric tests, one of these is the Group-Bourdon dot-cancellation test - the infamous dot test! This tests your ability to accurately concentrate on a repetitive task. The test requires you to cross out groups containing four dots, while ignoring groups containing three or five dots. Sounds easy doesn't it? Yet this test is the one that most candidates fear, and also the one that many will fail!