The following came to me from Roger Cholewiak (Princeton). I've put the info on my perception web page, but I thought that those of you who taught intro or perception might be interested in a neat demonstration. Hugh ----- Roger wrote: I've been working with a quite powerful (and safe) demonstration of the division of modalities in the sense of taste. Gymnemia sylvestre has been described often by Linda Bartoshuk and others as a taste modifier. It selectively abolishes the sensation of sweet, leaving all other taste modalities intact. I don't tell the students what the experience will be, but I do insure that they understand that they are under no obligation to participate in the demonstration. Gymnemia is sold over the counter as a tea in Japan as a (misdirected) treatement for diabetes, and I assure the students that the tea can be swallowed or spit out if they want. There is a large pseudoscientific body of literature on the Web regarding gymnemia's use in diabetes, and might be an interesting side discussion regarding research on the web. Anyway, the tea tastes very much like spinach tea, if you could imagine. After a water wash, there is no aftertaste, then the demonstrations begin as described below. These are notes I've sent to some of my friends who also teach S&P. Although my original sources were herbalists in India, it is now possible to buy gymnemia in a number of places stateside. I have been very happy with the price/ service/ cooperation of Wild Earth Herbs: Other refs are http://www.natplus.com/np_herbs.htm or http://www.vrp.com. Linda Bartoshuk talks about G.S. in her article "After Dinner Talk Taste Illusions: some demonstrations." Ann NY Acad Sci, 237, 279-285, 1974. <http://www.sageways.com/wildeart/herbs.html> They're in Houston - I buy 6 oz of g.s. in the "cut and sift" version (versus the powder) at 0.75 per oz. It came in a couple of days and they did it with a credit card. I used c. 1/4 cup of the leaf per quart of boiling water and steep it for about 10 minutes. I kept it cold in the refrigerator. With my studentss I do a PTC demo first, then I have them swish (and drink if they want) about 1/3 of a dixie cup of the tea. Then they rinse with water to get rid of any residual taste. Then they first start with tasting salt, then sugar, Sweetarts, and finally M&Ms. I only tell them that it will affect their sense of taste without telling them how. I give them the opportunity NOT to taste if they don't want to (informed consent), and also preface the whole thing by telling them that the tea will taste like spinach tea, but it won't taste so bad if they hold their nose. I scratch my head when they all first report no change in the taste of salt from the Burger King packets that I collect over the year, saying oh well, let's see if there's any effect on sugar. They each have a sugar packet. The looks on their faces are remarkable as they try the sugar. It tastes like melting sand on the tongue. There is no sweet taste, at all. The sweettarts are purely sour, and the chocolate is quite bitter. I leave it to you to try the artificial sweetners. The effect lasts for 10 to 20 minutes, and they all seem to enjoy the clearly defined demarcation among the qualities defined by this psychophysical dissection. ----- ---------------------------------------------------------- Hugh Foley | | Department of Psychology | | Skidmore College | KEVIN E | Saratoga Springs, NY 12866 | | (518) 580-5308 | | [EMAIL PROTECTED] | | http://www.skidmore.edu/~hfoley | | ----------------------------------------------------------
