A pill to erase bad memories. Doesn't it just sound so tempting? Surely everyone in the midst of a painful breakup has fantasised about wiping out all recollection of the relationship, Eternal Sunshine of the Spotless Mind-style? In reality, the drug in the news today is more likely to be used to help those suffering from conditions such as post-traumatic stress disorder after devastating experiences such as terrorist attacks or natural disasters, or other emotional problems. But the idea of tampering with the inner workings of the mind has raised concerns about the psychological consequences for individuals involved, and even the potential practical effects on society.