I have a keen interest in the subject of working memory. I lost a great deal of memory function while living in our toxic home. I also have an interest in the subject of chemicals. Because of our exposure, we have eliminated them from our home and diet.
Last fall the staff at our small charter school allowed me to conduct a science experiment. The experiment asked one question: Do chemicals and/or essential oils affect working memory?
The chemicals used were perfume, dryer sheets, and window cleaner. The essential oils were lavender, peppermint, and rosemary.
We decided to allow each child to participate. Some would be test givers; others would be test takers. More than 40 students participated over the course of two weeks. We conducted control tests measuring the working memory of each participant using Digit Span Testing.
According to Psychology Wiki:
Digit span testing is a measure of memory span which is the number of items, usually words or numbers, that a person can retain and recall. Where numbers are used it is also known as digit span, and the test is called digit repetition. It can be seen as a measure of working memory (or short-term memory, depending on the psychological framework used), although other factors such as attention and comprehension also contribute to the performance on this test.
In a typical test of memory span, a list of random numbers is read out at about the rate of one per second. The test begins with two to three numbers, increasing until the person commits errors. Recognisable patterns (for example 2, 4, 6, 8) should be avoided. At the end of a sequence, the person being tested is asked to recall the items in order. The average digit span for normal adults without error is seven plus or minus two.
Reverse repetition is more difficult and requires more processes besides immediate recall.
Here is one of our test sheets:
The directions were as follows:
"I am going to say a series of numbers for you to remember. When I am finished, I want you to say them in the reverse order in which I said them. Do you understand, or should I give you the directions again?"
On separate days we asked the participants to smell a designated scent for 30 seconds. We had them wait silently for two minutes and then tested them with the alternate set of numbers.
Our findings were inconclusive for the most part, with one significant exception.
Colin's graph shows the increase and decrease in scores for the three essential oils. Rosemary clearly had an impact on working memory. Of the 43 test subjects, 2 scored lower after smelling the oil, 11 remained the same, and 30 showed improvement. What is even more interesting is that those 30 individuals improved by a total of 46 points!
Our experiment simply validates what Greek scholars knew centuries ago. They wore garlands of rosemary during examinations for focus and recall. Shakespeare understood this benefit as well. In his play Hamlet, Act 4 Scene V, Ophelia gives her brother Laertes a flower, saying, "There's rosemary, that's for remembrance."
This 2003 study concluded that "rosemary produced a significant enhancement of performance for overall quality of memory and secondary memory factors, but also produced an impairment of speed of memory compared to controls." (We didn't test the speed of the recall, simply the performance.)
What is it about rosemary that helps memory? According to Dr. James Duke, former U.S. Department of Agriculture chief of medicinal plant research, "Rosemary contains more than a dozen antioxidants and a half-dozen compounds reported to prevent the breakdown of acetylcholine." Acetylcholine is a vital neurotransmitter, and when compromised, has been implicated in memory deficits associated with Alzheimer's disease. See this article for other reported health benefits of rosemary.
Greek scholars, Shakespeare, and a USDA official all agree with our middle school students. Rosemary is a wonderful herb well worth. . . remembering!