Dr. Gwaltney a professor at the University of Virgini School of Medicine, infected six student volunteers with rhinovirus; a virus that attacks the nsal mucus membrane and is the most common cause of colds. A few days later, when they were coughing and sneezing, he gathered 37 more people and divided them into three grops. Group 1 members spent three days and nights in the same room as one of the infected students, separated by screen so they could not touch one another. Group 2 sat round a table while an infected volunteer talked, coughed and sang to them. Group 3 held hands with an infected student for ten seconds, and then touched their own noses or eyes.