ABSTRACT
I like to think it was not an error, but a deliberate ploy, based on the ‘expectancy effect’: what you get is what you expect. Two American researchers once told teachers that they had identified certain pupils who would be making an unexpected spurt. The children had been chosen at random, but the researchers claimed they improved nevertheless, simply because their teachers expected them to. Actually the research was flawed and subsequently discredited, but it made a good story.
