Latin for “I will please”, the word placebo and the placebo effect means just that. Commonly used in research, a placebo is an inactive substance that would otherwise have no effect. However, because of the power of suggestion, when told that the placebo has an effect, the subjects receiving the placebo will believe and report that it does. This results in the placebo effect. Although placebos and the placebo effect are often spoken of in the context of medicine, occurrences of placebos and its effect have been commonly observed outside of medicine (Carroll). The placebo effect has been known for many years and numerous experiments have been conducted to test its power.

E. Morton Jellinek, Sc. D., conducted one of the most well-known experiments concerning the placebo effect in 1946. Jellinek set up a trial involving 199 subjects (originally 200) to test three different drugs: drugs A, B, and C. Drug D was also placed amongst these as a placebo. The design of the experiment was different from older experiments involving placebos in that older experiments used placebos to “express the efficacy or non-efficacy of a drug in terms of “how much better.” The subjects suffered from frequent headaches and were divided into four test groups. Jellinek had each group take all four drugs, though the order between the groups was different. In the end, 120 of the 199 subjects responded to the placebo and the experiment proved to be another example of the power of the placebo (Jellinek 87-91) .

As mentioned earlier, the placebo effect present not only in medicine. An experiment set out to measure the response of humans when under the influence of alcohol is a famous example. Some subjects were given successive doses of alcohol and their responses were measured after each dose. Other subjects were instead given a placebo meant to mimic the taste of alcohol and it was suggested to these subjects that what they was drinking was indeed alcohol. As expected, the group that was given actual alcohol exhibited signs of drunkenness and lack of coordination. What was surprising was that the placebo group exhibited the same signs, with some even seeming drunk. It seemed that the mere suggestion of drinking alcohol produced inebriated behavior (Henderson).

Scientists generally agree that for the placebo effect to occur, the subject must believe that he is given effective treatment and that it must be suggested to him that the treatment is effective. The question of how and why placebo responses are generated is still a matter of debate and three well-known theories have been proposed, though these three are not necessarily mutually exclusive. The first theory argues that the placebo effect is the result of the subject-expectancy effect: subjects will expect a given result and will therefore report that result. Another theory argues that it is the result of classical conditioning. Proponents of this theory explain that people are conditioned to associate a particular stimulus with a particular response. With confronted with a stimulus of a placebo that is perceived to be medicine, subjects will give off the appropriate response, which is relief. The last theory proposes that motivation to feel better and cooperate with an experimenter to be the ultimate cause (Carroll).

The present study conducted by Shunan Zhao is not meant to provide evidence for or against any of these theories. Instead, this study is solely meant to reproduce the placebo effect. The study will not involve medication, but the idea behind the placebo effect still remains. Suggestion will be used to have subjects give a particular response when given a normally neutral stimulus that would not elicit such a response. Another purpose of this study is to provide evidence for the idea that certain types of water tastes better than other might actually be in the mind. Judging from past experiments, the vast majority of participants in this study will be susceptible to the placebo effect and will taste differences of the same water, but in different bottles. Participants will also give the “tap water” a significantly lower score than the other types of water.

Method

There was as total of 31 participants. All the participants were students, with some in high school, some in middle school, and some in elementary school. The majority of the participants were in high school because it was more convenient to obtain high school students. Since all the participants were students, their ages were around the same. Although there were more male participants than female participants, gender was not a determining factor when the participants were selected. The reason why the gender was not evenly distributed might be attributed to the fact that there are generally more males than females. APA ethical standards of anonymity were observed by allowing the participants to not include their names if they did not want to.

The participants were not randomly selected, at least not in the sense of a simple random sample. Students that were selected shared the same study class as Zhao or were part of a group of children that Zhao volunteered to look after. The reason for this was solely because of convenience. It would be unreasonable to select a simple random sample of Bromfield students. Not only would that be too time consuming, many randomly students may not even agree to take part in the study. All the students in the study class were asked whether or not they would like to participate in a psychology study. Those who agreed were the participants. Similarly, all the children that Zhao volunteered to look after were asked whether or not they would like to participate in a psychology study and those who agreed also became the participants. The participants were not assigned into groups since control or treatment groups were not necessary for the purpose of this study.

The materials used were four bottles of water, 31 plastic cups, and a questionnaire. The four bottles of water were bottles of Aquafina, Dasani, Poland Springs, and tap water. The bottle of tap water was a simple bottle that did not have a label and it gave off a yellowish color. The appearance of the other bottles of water, the brand waters, was not altered in anyway. However, they all contained the same tap water as the tap water bottle. The questionnaire contained the names of the four bottles of water along with an area to give a grade for each bottle and write any additional comments. Because participants needed writing utensils to complete the questionnaire, they were provided if necessary. An example of the questionnaire is attached. The plastic cups were normal plastic cups that did not affect the taste of the water in any way.

After the participants were selected, they were told to gather around and not to talk to any of the other participants. This was to ensure that verbal communication amongst the participants would not influence them in any way. After the participants had gathered around, they were told that they would sample four different types of water. They were told to give a grade of one through 10, with ten being the best taste. They were also told to write additional comments if they feel the need to do so. After plastic cups were passed to each participant, the participants were told that they would begin by sampling Aquafina. While pouring tap water from the Aquafina bottle into their cups, the participants were told that Aquafina was a very pure and fresh water from the glaciers atop of Mt. McKinley. After grading Aquafina, the participants were made to sample the tap water in the Dasani bottle. This time, they were told that Dasani is also a very pure water that has been enhanced by minerals. After Dasani was given a grade, the participants were made to sample tap water from the Poland Springs bottle. This time, they were told that the Poland Springs water comes from a natural source of water: the clean spring water of Maine. After Poland Springs was given a grade, the participants were made to sample the last bottle of water, the tap water. The participants were told that the tap water comes from the school’s tap water system and that it was generally poorly received. They were also shown the bottle, which gave off a yellowish tint. After a grade was given to the tap water, the study was finished.

Because it was rather difficult to gather 31 students all at once, several trials were performed, with about ten participants in each.

Analysis

The mean grade for the tap water in the tap water bottle is 5.26. This is considerably lower than the mean grade for the other bottles Aquafina, Dasani, and Poland Springs, which are 7.4, 6.5, and 8.08 respectively. Because it was suggested to the participants that the tap water would taste bad, it was expected that the mean grade for the tap water to be lower than the others. When the mean grades of the brand waters are averaged together, a mean grade of 7.33 is obtained. When compared to the mean grade of 5.26 that the tap water received, the mean grade 7.33 of the brand bottles is much higher.

After a confidence interval was calculated, it can be shown that there is a 95 percent chance that the true difference between the mean brand bottle grade and the mean tap water grade is between 1.16 and 2.98. In other words, if the entire population of nine to 17 years old students were asked to grade the taste of the waters, there is a 95 percent chance that the mean grade of the brand water is between 1.16 and 2.26 higher than the mean grade of the tap water. Additionally, a hypothesis test was conducted and it was ultimately concluded that the difference between the mean grade of 7.33 and 5.26 is very statistically significant. It is very likely that the results did not arise out of chance.

The fact that tap water was not well received is emphasized by the fact that 64.5 percent of the participants gave it the lowest score, or one of the lowest scores. If a participant gave two or more scores that were all the lowest, and tap water received one of these scores, then he is part of that 64.5 percent. However, if a participant gave all the bottles the same score, then he is not included in tat 64.5 percent seeing as he realized the bottles contained the same water. After obtaining a confidence interval, it can be established that there is a 95 percent chance that the true population proportion of nine to 17 years old students who would give the tap water the lowest score is between 0.477 and 0.814. This shows that the majority of the population to whom the results can be generalized would also give the tap water the lowest grade.

Of the 31 participants, only two realized that the waters were the same and were not supposed to taste different. This indicates that 93.5 percent of the participants gave at least two different grades. This also means that 93.5 percent of the participants tasted a difference. After calculating a confidence interval, it can be established that there is a 95 percent chance the true population proportion that is relevant and that would give different grades is between 0.849 and 1. Thus, the vast majority of the population would give different grades.

There was an interesting observation made. 10 of the 31 participants were females, meaning that 32.3 percent of the participants were females and 67.7 percent of the participants were males. The number of females that gave different grades is 10 and for the males, it is 19. This does provide enough evidence to suggest that females are more likely to give different grades and therefore taste a difference between the waters. However, the number of women that gave the lowest grade to tap water is nine. This seemed significant when compared to the fact that only 11 of the males gave the lowest grade to tap water. This meant that of the participants that gave tap water the lowest grade, 45 percent were females and 55 percent were males. It seemed that women are more likely to give tap water the lowest grade. However, after a hypothesis test was conducted to examine this claim, it was ultimately concluded that the results were not statistically significant. With a p-value of 0.18, it meant that it is likely women are not prone to giving the tap water the lowest grade.

Graphs

Conclusion

The results supported both parts of my hypothesis. It was concluded through the results that the vast majority (93.5 %) of the participants tasted a difference in the waters, showing that they were susceptible to the placebo effect. It was also concluded through the results and a hypothesis test that the participants gave the tap water a significantly lower grade. Since confidence intervals were calculated, these results could be generalized to the population of nine to 17 years old students.

As mentioned earlier, the purpose of this study was not to refute or approve of any of the theories regarding why and how placebo responses are generated. However, it was unlikely, at least in this case that the placebo responses were generated by the participants’ motivation to cooperate with the experimenter. The participants did not know whether giving a high or low grade would help the experimenter.

A few conclusions could be drawn about human nature and behavior, the most obvious of which is that humans are very susceptible to the placebo effect. This study also provides evidence to why people think bottled water tastes better. Although a lot may genuinely think that bottled water tastes better, much of the reason why they think so may well be in the mind. Some participants of this study gave very high scores to certain brands of bottled water, even though what they were essentially drinking was tap water in a fancy bottle. Some participants later stated that they felt the Poland Springs water tasted truly like Poland Springs water.

This study’s demonstration of the power of the placebo may also shed light as to why some people truly believe and claim alternative forms of medicine are effective, even when they have been scientifically proven to be ineffective. Today’s world is filled with famous alternative forms of medicine and treatment, all of which have been debunked over and over by scientists. There are magnet therapists who claim that pain is caused by the iron in the blood, exorcists who claim it is caused by being possessed by a devil, and chiropractors who claim it is due to the back bone, even if the pain nowhere near the backbone. Even though such theories truly make no sense and are not supported by any empirical scientific evidence, practitioners of these theories still manage to gather a large number of believers. One logical and scientifically supported explanation for this popularity is because of the placebo effect. If these patients truly believe that they are being treated with the right medicine, they will feel better. After all, pain, depression, and so many different illnesses are all in the mind. Over time, such illnesses may naturally go away, but the patients will attribute the disappearance of symptoms to the alternative medicines. This increases their confidence in these alternative medicines, and the profit of the false doctors (Butler 74-95).

If this study was to be repeated again, it would be in the form of an experiment. There would be a control group who would actually be told to drink the real water and not tap water in different bottles. Then, there would be a treatment group that would drink the fancy tap water. In such a case, a cause-and-effect relationship could be established. Even though placebos usually serve as the control group, the purpose of this experiment would be to measure the effect of the placebo, not the effect of the actual bottles of water.

Furthermore, there would be more subjects so that the results can be more effectively generalized. It would be good if the subjects could be selected from a simple random sample despite how unreasonable that is because then, the results could be better generalized. There was also a confounding variable: it was not known whether or not the participants experienced the placebo effect as a result of hearing what the experimenter said and expecting to taste what the experimenter said or expecting the taste that they had always received from past experience, or even both. Such confounding variables would be eliminated next time by either saying nothing and having the participants drink out of those familiar bottles or by presenting the participants with brands they had never heard of and then suggesting the taste of the brands through words. A last major bias in this study was that even though the participants were told not to talk to each other, their facial expressions were still visible for the other participants to see. Such facial expressions associated with a good or bad taste may influence the decisions of the fellow participants. It would be much wiser to test each subject separately and alone.