By: CHRISTOPHER SHEA, The Wall Street Journal
Wednesday, February 15, 2012
February 13, 2012
What’s your favorite kind of Hershey’s kiss? Forget about your preconceptions. Depending on the circumstances of the taste test, it’s quite likely to be the last one you taste.
Two psychologists at the University of Michigan, Ed O’Brien and Phoebe C. Ellsworth, gave a taste test involving different flavors of the Hershey’s candies — milk chocolate, dark chocolate, caramel, crème, or almond — to 52 students. The order in which the students tasted the candies was random; the students were also randomly divided into two groups. The only difference was that some students knew when they were eating the last candy, and the others didn’t. (One group heard “Here is your next chocolate” five times, and the other heard “Here is your last chocolate” before the final round.)
Students who knew the fifth chocolate was the last rated it considerably tastier (8.2, on a 10-point scale) than those who experienced it only as one in a series (6.3). Additionally, those who knew the fifth candy was the last chose it as their favorite 64% of the time, compared to 22% for those who were unaware.
The influence of such “end effects” has long been known in psychology. Famous experiments by Amos Tversky and Daniel Kahneman showed that patients rated equally painful surgery procedures as less painful when they ended on a relatively mild note, for example. (Patients even preferred longer procedures, with objectively more pain, to shorter procedures, if the longer procedures ended mildly.)
This new study is striking, its authors said, partly because of the “artificial and impermanent” nature of the ending analyzed. The conclusion of an uncomfortable medical procedure understandably sticks in the mind, but why the conclusion of a trivial taste test?
Perhaps evolution has trained us to pay special attention to the final item in a series, and to evaluate it favorably, out of fear of “anticipated scarcity,” the authors write. In any case, the authors suggest that their observation
"extends far beyond Hershey’s Kisses. For example, the last book of a series or the last speaker in a symposium may receive unwarranted praise, research subjects may give overly positive responses on the last tasks of experiments, and the last job applicants or students (e.g., those whose papers are graded last) may look especially qualified."