From the article: They then tested these volunteers in a room infused with either rosemary essential oil, lavender essential oil or no aroma. Participants were

From the article: They then tested these volunteers in a room infused with either rosemary essential oil, lavender essential oil or no aroma. Participants were told they were there to test a vitamin water drink. Any comments about the aromas were passed off as irrelevant and "left over from the previous group to use the room". ... The volunteers (and I [author]) then took a test which was designed to test their prospective memory. It's a clever test with many layers so you never quite know what's being tested.