IB Docs (2) Team
ERQ marking: Pheromones
Below you will find three sample ERQs for the question: Evaluate research on the potential role of pheromones in human behaviour.
For each of the samples, refer to the rubric to award marks. After each sample, there is a predicted grade as well as feedback on the strengths and limitations of the sample.
ERQ rubricSample 1
Pheromones are chemical substances produced and released into the environment that cause a behavioural or physiological response in other members of the species. In nature, pheromones are most commonly released by animals to signal to others; they are ready to mate, or that there is danger nearby. The impact of pheromones on human behaviour is a highly controversial topic in psychology since nobody has yet to identify a human pheromone. However, there has been much research done on the topic. Two studies intended to study the effect of pheromones on human behavior are Zhou's study of Androstadienone (AND) and Wedekind's study of the role of MHC (Major Histocompatibility Complex) on human mating behaviour.
Zhou wanted to see the impact of Androstadienone (AND), a potential human pheromone found in male sweat, on human sexual behavior. In the study, four groups of participants - heterosexual males, heterosexual females, homosexual males and homosexual females - were shown images of stick figures walking on a screen. Each group did one trial where they were exposed to the smell of cloves while they watched the stick figures moving on a screen and another trial where the cloves were mixed with a high dose of AND. The researchers found that in the trial with the AND, heterosexual females and homosexual males rated the stick figures as more masculine. The researchers also carried out the same study with the female version of AND (estratetraenol) and found similar results with heterosexual males and homosexual females. The researchers concluded that AND could be a human pheromone that carry plays a role in sexual attraction.
The fact that the effect of Androstadienone was only seen with heterosexual females and homosexual males does suggest that it impacts us on the basis of sexual orientation. However, even though the study is highly standardized, there are a number of issues present in the study. Firstly, the study is very artificial and therefore has a problem with ecological validity. The level of AND present in the study was at a far higher concentration than what is seen in human males. It could be argued that the levels of AND in the real world are too low to be detected. Finally, this study does nothing to show that AND or estratetraenol are used to signal mating behaviour or associated with attraction. Signalling pheromones are used to cause rapid behavioural changes leading to mating behaviour and there is no evidence for this. Additionally, Hare et al (2017) did a study attempting to replicate the findings of Zhou et al (2014) and failed to do so. For these reasons, this study cannot be said to prove the existence of a human pheromone.
Wedekind (1995) also carried out a study relating to the impact of pheromones on human behaviour. For his "smelly T-shirt study", Wedekind wanted to determine whether one’s MHC (a group of genes related to one’s immune system) would impact sexual attraction. First, he tested both men and women for their MHC. He then asked men to sleep in a given T-shirt for four nights and to use specific perfume free deodorants so the difference in each T-shirt smell would be due to the male’s natural smell. The women were then asked to rank the smell of 7 of the T-shirts. The researchers found that the women scored male body odors as better when they had a different MHC than their own. The researchers concluded that MHC influences sexual attraction.
This study does a good job of controlling for many possible confounding variables. One example is that the researchers ensured that the men wearing the T-shirts were all washing with odour free shampoos and soaps. The study also has an evolutionary explanation - the inheritance of a more diverse immune system means the child has a greater chance of survival. However, there are some issues with this study, especially with how it relates to pheromones. Firstly, the study shows that smell, specifically MHC, influences human sexual attraction. Smell is not the same thing as a pheromone and MHC is not a pheromone by definition, so although this shows evidence smell plays an important role in human attraction, it does not provide evidence for pheromones. The researchers also measured the level of "pleasantness" of the smell. This is not the same as initiating sexual activity, as would be expected with pheromones.
The research surrounding pheromones has been very controversial and the fact remains that no researcher has yet to definitively identify a human pheromone. Both studies above illustrate how smell can play an important role in human decision-making. Psychologists will likely continue to debate the existence of human pheromones but if there are human pheromones, it is highly likely that their effects are far subtler than what we see in the animal kingdom.
796 words
Focus on the question: The introduction clearly introduces the question and sets up the argument for the essay. A well focused response. 2 marks
Knowledge and understanding: There is clear undestanding of the role of pheromones. Terminology is used correctly. Some ideas could be more developed. 5 marks
Use of research: The research is well described and explained. The role of MHC could be a bit more developed. 5 marks
Critical thinking: There is well developed and highly relevant critical thinking with regard to the question. 6 marks
Clarity and organization: The essay is well organized and communicates ideas effectively. 2 marks
Total: 20 marks
Predicted: 7
Sample 2
Pheromones are chemical substances excreted from glands, which are supposed to trigger a social or sexual response form a member of the same species. So far, it has been hard to determine whether pheromones exist in humans, a real human pheromone has not yet been found. The research within the area of pheromones has a lot of limitations and can be difficult to apply in real life.
McClintock studied 135 female residents of a college dormitory. She wanted to see if a dominant female could influence the ovulation patterns of other women. She used questionnaires to determine the onset date of menstruation among roommates and close friends. The data showed a significant increase in the alignment of menstruation patterns over time. McClintock argued that this could be a pheromonal response. This study is limited because she did not actually isolate an phermones, but assumes that it is a pheromone that resulted in the change in mentruation patters.
A second study, performed by Zhou, focused specifically on the pheromones Androstadienone and estratetraenol which are found in male sweat and semen, and female urine respectively. The aim of the study was to find out whether these potential pheromones have an influence on sexual behaviour. This was a lab study, where 24 heterosexual men, 24 heterosexual women, 24 gay men and 24 lesbian women were used for the sample. The researcher created three conditions. In the first condition, they were all asked to determine the gender of stick figures walking on a screen, while having the smell of cloves mixed with androstadienone in the room. In the second condition, they were also asked to determine the gender of stick figures, but this time the cloves were mixed with estratetraenol. In the control condition, there were no pheromones mixed in with the cloves while the participants were identifying the gender of the stick figures. The results showed that heterosexual females and gay males were influenced in their decision making when androstadienone was present (they viewed the stick figures as more masculine), but heterosexual males and lesbian women’s results were influenced when estratetraenol was present (they viewed the stick figures as more feminine). These results show that these two substances which could potentially be pheromones, influencing sexual attraction.
A strength of this study is that it is highly standardized and a sample was used which allows for different sexual preferences. A limitation of this study is that there are problems with the ecological validity because the level of pheromones was much higher than it would be in real life. Having to identify the gender of a stick figure is also very artificial and probably does not apply to real-life situations. In a later study, when normal levels of the chemicals were used, the results were not significant. This indicates that the results are probably not reliable.
Both of these studies show some form of behaviour change, but both of them have been challenged and have many more limitations then they have strengths. Due to the fact that no pheromones have yet been found in humans, it is very hard to create studies which could show that pheromones do affect humans.
Focus on the question: The introduction clearly sets up the essay. The response could be more focused on evaluting research in a more holistic manner. 1 mark.
Knowledge and understanding: The response demonstrates some understanding of pheromones. Psychological terminology is used effectively. More discussion of the potential role of pheromones would make for a stronger essay. Links to behaviour are not well developed. 4 marks
Use of research: The first study is not highly relevant; although it could be a study of pheromones, it is not linked to a behavoiur, but to a physiological process. The second study is clearly explained. 2 marks
Critical thinking: There is some evidence of critical thinking. There is an attempt to both evaluate the studies, but this is not well developed. 3 marks
Clarity and organization: The response is well-organized and language communicates effectively. 2 marks
Total: 12 marks
Predicted: 5
Sample 3
Pheromones are chemical substances produced and released into the environment by an animal affecting the behaviour or physiology of others of its own species. There are two types of pheromones that are agreed on by psychologists, one of which is primary pheromones and the other is signalling pheromones. Primary pheromones are causing slow and long-term physiological effects such as hormones effects. Signalling pheromones are released by an animal for the purpose of arousing mating behaviours in a rapid way of transferring.
Wedekind et al have carried out a lab experiment investigating the role of MHC, a set of genes that are responsible for the immune system, on human mate selection. The sample had a wide sample range of MHC. The male participants were asked to sleep in a t-shirt that was handed from the investigators for two nights and conserve the t-shirts in a plastic bag during the day. The male participants were asked to use perfume-free detergent and soap as well as that they are not allowed to use any perfumes or deodorants, smoking, drinking alcohol, absorb spicy food or to have sexual activities during the experiment. The female participants were asked to smell 7 t-shirts that were put into individual boxes through the holes. Between the 7 t-shirts, there is a control which was not worn by anyone before and three from a man who has similar MHC with females and three from men who have a huge difference in between their MHC and the females do. The women were asked to score the t-shirts from 0 to 10 on its odour intensity and the amount of pleasure or sexiness of the odour. The result of this experiment was female rated the odour of a higher score on the t-shirts worn by a man who has dissimilar MHC to their own ones. And that the result is reversed for a female who took contraceptives. Therefore, the researchers suggested that the MHC played a role mate selection as the more different of MHC a man owns, the more attractive he is to women. One of the limitations of this study is that the sample population that the researchers choose may not be representative due to the fact that they are similar in age and cultural background.
Zhou carried out a study to investigate the role of AND, an endogenous steroid exists in male human sweat, on human’s sexual behaviour. The sample was made up of heterosexual males and females and homosexual males and females. Both heterosexual and homosexual had an equal amount of participants in both genders. There are two types of conditions were provided, the control group the participants experienced the smell of clove and the experimental group experienced a mixture of clove and AND. The participants were asked to watch different diagrams of stick figures and identify their genders under one of the two smell’s conditions. The results demonstrated that heterosexual females and homosexual males under the condition mixed with AND shows a higher rate of identifying stick figures as masculine than controlled conditions that did not contain AND.
Both studies' results have suggested the scent from human bodies, MHC and AND, do have an impact on the mate selection and help to attract opposite sex. However, it does not suggest pheromones existence and its role in human behaviour. The study by Wedekind was not a study on pheromones but rather a type of human scent from the immune system genes. This does not match the definition of pheromones as a type of chemical. Furthermore, the body sweat might be influenced not only by MCH, but also other variables such as bacteria and diet. In Zhou’s case, a researcher attempted to replicate the study but they failed to confirm the results that Zhou got. This might be due to a fact that Zhou she put a significantly higher dose of AND in the cloves than a normal body can produce. In conclusion, it is hard to show there is evidence that human scent influences people’s mating choice in these studies and its numerous limitations.
Focus on the question: There is an attempt at focus, but it is not well sustained. The introduction does not clearly frame the argument for the essay. 1 mark.
Knowledge and understanding: There is some knowledge and understanding demonstrated, but psychological terminology is not developed. MHC lacks a clear explanation as to why it would be considered important in choosing a mate. 3 marks.
Use of research: There are two studies used to support the essay, but the results of neither study are really well explained in terms of the pheromone. 3 marks.
Critical thinking: There is very limited evaluation of the two studies that are described. There is an attempt at a more holistic approach to evaluation, but this is not well developed and at times a bit unclear. 3 marks.
Clarity and organization: Language and organization are not always clear. 1 mark.
Total: 11 marks
Predicted: 5
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