The American screenwriter and film director Billy Wilder referred to the perfect vision of hindsight; “hindsight is always twenty-twenty”. But hindsight may also distort and prejudice our judgment of past events in a way that it is difficult to compensate for. A 28 year old paper, part of a doctoral dissertation submitted to the Hebrew University of Jerusalem, has been reprinted in Quality and Safety in Health Care under the heading “Classic Paper”.

The three experiments described in this paper, together with a fourth referred to briefly, show that thinking that we know the outcome of a series …