Stereotyping certain groups of people as being like a robot or animal is a subtle form of dehumanization, say Australian psychologists.

And understanding the phenomenon could help avoid more serious dehumanization normally associated with discrimination, warfare, genocide and torture.

"There's been lots of work on how dehumanization occurs in wartime; how thinking about the person you're harming as 'less than human' enables you to inflict harm on them," said Haslam.

http://dsc.discovery.com/news/2007/05/07/stereotype_hum.html

Next time an armed horde threatens to sack your town and slaughter your family, do remember that each and everyone of them is a caring, sensitive individual, with their families and distinct humane qualities — probably more worth of life than anyone you knew.