The ability to speak is one of the essential characteristics that distinguishes humans from other animals. Many people would probably intuitively equate speech and language. However, cognitive science research on sign languages since the 1960s paints a different picture: Today it is clear, sign languages are fully autonomous languages and have a complex organization on several linguistic levels such as grammar and meaning. Previous studies on the processing of sign language in the human brain had already found some similarities and also differences between sign languages and spoken languages. Until now, however, it has been difficult to derive a consistent picture of how both forms of language are processed in the brain.