Pavlov showed that dogs can be conditioned to salivate when hearing a sound by giving them a treat for a period of time upon first hearing that sound. Recently a similar phenomenon with the immune system has been observed. According to an article published on Scientific American, for three days, subjects were given an immunosuppressive drug with a strawberry flavored milk that had a lavender scent. Then 5 and 11 days later they were given the same drink but with a placebo. Compared to the control group, the experimental group’s immune systems were significantly inhibited, as shown by levels of immunoresponsive molecules in their blood. This learned behavior could greatly limit the side effects caused immunosuppressive drugs.
To read the article, take a look at: