This week I somehow came across the Seminars About Long Term Thinking podcast, and listened to an episode with the psychologist Daniel Kahneman. At one point in the discussion, he mentioned a study by Paul Rozin that investigated the effect that placing a label saying "cyanide" on a bottle had on participants' willingness to drink the contents inside.
The results of the study, copied here from the Journal of Personality and Social Psychology under the title "Operation of the Laws of Sympathetic Magic in Disgust and Other Domains" (emphasis is mine):
Cyanide label-1. In this procedure, we ascertain whether the label "sodium cyanide" imparts its quality to the substance it labels...Subjects returned to their seat at the table and were presented with two brown glass 500ml "chemical" bottles, each about one-quarter filled with a white powder, which was, in fact, sucrose. One had a typed label on it that said "Sucrose (Table sugar)," the other had a typed label that said "Sodium Cyanide" with a red printed "Poison" sticker below it. The experimenter said:
"Here we have two bottles with powder in them. The powder in both bottles is sucrose, that is, table sugar. These are brand new bottles that we just bought. They never had anything in them but sugar. This bottle (on the subjects' left) has a sucrose label that we put on it. It's a brand new label, that was never on any other bottle. This other bottle (on the subjects' right) has a brand new sodium cyanide label on it. This label was never on any other bottle and was never even near cyanide. Remember, sugar is in both bottles."
The experimenter set out two different colored plastic cubs, one in front of each bottle, and poured water from a glass pitcher into both, until they were about half full. Now, using separate, new plastic spoons for each bottle, the experimenter put a half spoonful of powder from the "sugar" bottle into one cup, and stirred it. The spoon was discarded, and the same was done with the sugar in the cyanide bottle, with a new spoon. The subject then rated, on the 200mm line, how much he would like to drink from each of the cups, and stated a preference between the two. The subject was then asked to take a sip of the sugar water from the preferred cup, and subsequently to account for his or her choice.
Cyanide label-2. We thought avoidance of the cyanide-labeled bottle might be motivated by doubts about the real contents of the bottle (though it seems absurd that the experimenter woudl try to poison the subject by offering a poison-labeled bottle). For this reason, in the second sequence, the subject himself labels the bottles. Initially, we performed this second test only for subjects who indicated a substantial preference for the sugar-labeled bottle's contents. The last 20 subjects, however, were run on this procedure independent of their results on the first sequence. The total N for the second procedure was 38; that is, 12 subjects were eliminated on the basis of their performance on the first cyanide test.
Previously used bottles and glasses were taken away, and two similar, empty bottles were brought out. The covers were removed, and sugar from a 5-lb box of locally sold "Domino" sugar (sucrose) was poured into each bottle (to a level of about one-third full). The subject was then given two peel off labels on a piece of paper. On read "Sucrose (table sugar)," the other read "Sodium Cyanide." (Through an error, this cyanide label did not have a red "Poison" sticker affixed to it.) The subject was asked to put one label on each bottle, in any way he wanted. Then, the procedure used for Cyanide Label 1 was repeated (mixing sugar water, rating of both solutions, indicating a preference, and sipping the preferred solution).
...
The sugar labeled as "Sucrose" was preferred to the sugar labeled as "Sodium Cyanide" by 41 of 50 subjects (p < .001). The mean difference between the cyanide- and sugar-label ratings was -30.58 (p < .001). When asked to explain their choice, the most common responses were reference to the label, and no response. Only 1 subject suggested the possibility that there might be cyanide in the cyanide-labeled bottle. The second cyanide manipulation, in which the subject put the labels on herself, showed a much smaller but still significant effect, with a net difference of 16.5 points between cyanide and sugar.
Wild.
This reminds me of the anchoring effect, described famously by Tversky and Kahneman in 1974 (nb. I was aware of this study previously - it comes up a lot in the literature on negotiation - but certainly couldn't have told you who the authors were. Before setting out to write this post, Kahneman's name would have meant nothing to me.). From their paper, "Judgment under Uncertainty: Heuristics and Biases" (emphasis is mine):
Insufficient adjustment. In a demonstration of the anchoring effect, subjects were asked to estimate various quantities, stated in percentages (for example, the percentage of African countries in the United Nations). For each quantity, a number between 0 and 100 was determined by spinning a wheel of fortune in the subjects' presence. The subjects were instructed to indicate first whether that number was higher or lower than the value of the quantity, and then to estimate the value of the quantity by moving upward or downward from the given number. Different groups were given different numbers for each quantity, and these arbitrary numbers had a marked effect on estimates. For example, the median estimates of the percentage of African countries in the United Nations were 25 and 45 for groups that received I0 and 65, respectively, as starting points. Payoffs for accuracy did not reduce the anchoring effect.
Studies like these are totally fascinating to me, and have the effect of reinforcing the skepticism that I am inclined to approach all statements which lack some method of independent verification. I also try to remain aware of the danger of taking self-reported data at face value: In my experience, people (including myself) are notoriously bad at knowing what's going on in their own heads.
For the intrepid among you, there's a bunch of great throwaways on anchoring on its wikipedia page. An excerpt:
Even when the anchor value is obviously random or extreme, it can still contaminate estimates. One experiment asked subjects to estimate the year of Albert Einstein's first visit to the United States. Anchors of 1215 and 1992 contaminated the answers just as much as more sensible anchor years. Other experiments asked subjects if the average temperature in San Francisco is more or less than 558 degrees, or whether there had been more or fewer than 100,025 top ten albums by The Beatles. These deliberately absurd anchors still affected estimates of the true numbers.
Insane. It's worth stating explicitly that, when entering into negotiation, one should be acutely aware - and wary - of anchoring strategies.