Researchers at the University of Cambridge and the Ecole Normale Supérieure in Paris recorded the EEG (brain waves) on a group of participants while they were awake. They repeated the experiment while participants were sleeping. However, they used different words of animals and objects. Obeservation of sleeping brain activity showed that the participants continued to respond accurately to the words although more slowly than when they were awake. According to researcher Sid Kouider, the study showed that speech processing and other complex tasks can be done without being aware of what you perceive. It may be that such unconscious processing is likely not limited by the complexity of the task but by whether or not it can be performed automatically.