The title of the film "Flattening of Affect" comes from psychology, and refers to the absence of emotional response in certain psychiatric patients. It is often a symptom of schizophrenia, but is also characteristic of psychopaths since it allows them to commit acts of violence with little or no remorse. I first heard the term when reading Philip K Dick's Do Androids Dream of Electric Sheep? in which the protagonist imposes a test called the Voigt-Kampff Scale on those suspected of being androids. To score low on this test implies an impaired empathic ability - or flattening of affect - and hence shows that they are not human, since empathy is mainly a human characteristic.
