Task: Question Answering
Input (English): Context: Something in chocolate could be used to stop coughs and lead to more effective medicines, say UK researchers. Their study found that theobromine , found in cocoa, was nearly a third more effective in stopping coughs than codeine, which was considered the best cough medicine at present. The Imperial College London researchers who published their results online said the discovery could lead to more effective cough treatment. "While coughing is not necessarily harmful it can have a major effect on the quality of life, and this discovery could be a huge step forward in treating this problem," said Professor Peter Barnes. Ten healthy volunteers were given theobromine, codeine or placebo, a pill that contains no medicine, during the experiment. Neither the volunteers nor the researchers knew who received which pill. The researchers then measured levels of capsaicin, which is used in research to cause coughing and as a sign of how well the medicines are stopping coughs. The team found that, when the volunteers were given theobromine, the capsaicin needed to produce a cough was around a third higher than in the placebo group. When they were given codeine they needed only slightly higher levers of capsaicin to cause a cough compared with the placebo. The researchers said that theobromine worked by keeping down a nerve activity , which cause coughing. They also found that unlike some standard cough treatments, theobromine caused no side effects such as sleepiness. 
 Question: What was used in the experiment to cause coughing?
Output (English): capsaicin.