Effects of Olfaction and Pheromones | Literature Review

Effects of Olfaction and Pheromones | Literature Review Abstract: A favorable scent goes a long way. An odor or fragrance (commonly referred to as a smell) is caused by one or more volatilized  chemical compounds, generally at a very low concentration, that humans or other animals perceive by the  sense  of  olfaction. Odors are also commonly called scents, which can refer to both pleasant and unpleasant odors. Scent plays a very important role in our lives. A pheromone is a secreted or excreted  chemical  factor that triggers a social response in members of the same  species. A survey of sample size 30 college students was conducted to find out if scent did attract attention or not. Keywords: Olfaction, human pheromones, MHC genes Introduction: Want to boost your mood or stir up old memories? Just use your nose. And, most important, scent can even drive one to romantic distraction. Think of your partners pajamas. Indeed, the nose can suss out something as complex as sexual compatibility. The terms fragrance and aroma are used primarily by the food and cosmetic industry to describe a pleasant odor, and are sometimes used to refer to  perfumes. In contrast, malodor, stench, reek, and stink are used specifically to describe unpleasant odor. In the  United Kingdom, odour refers to scents in general. In the United States, odor has a more negative connotation, such as smell, stench or stink, while scent or aromas are used for pleasant smells. Research has shown that certain human body odors are connected to human sexual attraction. Both fluctuating asymmetry (FA) and the human leukocyte antigen (HLA) are connected to scent. Review of literature: OLFACTION Olfaction or olfactory perception is the  sense  of smell. Many vertebrates, including most mammals and reptiles, have two distinct olfactory systems—the main olfactory system, and the accessory olfactory system which is mainly used to detect pheromones. In female humans, the sense of olfaction is strongest around the time of ovulation, significantly stronger than during other phases of the menstrual cycle and also stronger than the sense in males. The MHC genes (known as HLA in humans) are a group of genes present in many animals and important for the immune system; in general, offspring from parents with differing MHC genes have a stronger immune system. Fish, mice and female humans are able to smell some aspect of the MHC genes of potential sex partners and prefer partners with MHC genes different from their own. Humans can detect individuals that are blood-related kin (mothers/fathers and children but not husbands and wives) from olfaction. The ability to identify odors varies among people and decreases with age. Studies show there are sex differences in odor discrimination; women usually outperform males. Pregnant women also have increased smell sensitivity, sometimes resulting in abnormal taste and smell perceptions, leading to food cravings or aversions. Olfactory Reference Syndrome (ORS) is a condition in which those affected have an excessive preoccupation with the concern that body odor may be foul or, on a good day, unpleasant. HUMAN PHEROMONES A pheromone is a secreted or excreted  chemical  factor that triggers a social response in members of the same  species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual. While humans are highly dependent upon visual cues, when in close proximity smells also play a big role in sociosexual behaviors. There is an inherent difficulty in studying human pheromones because of the need for cleanliness and odorlessness in human participants. The focus of the experiments on human pheromones has been on three classes of putative pheromones: axillary steroids, vaginal aliphatic acids, and stimulators of the  vomeronasal organ. Pheromones have been demonstrated clearly in other species, but their existence and ability to affect humans is still under debate. Several studies have been conducted that have reached different conclusions, but some pheromone effects seen in other mammals are definitely present in humans. Most studies have found that human sweat or putative pheromones increase physiological arousal, one way or another. This idea that something we cant even consciously smell is affecting our behavior is horrifying to some people, but in reality we are controlled by the combination of all our senses! Gustav Jà ¤ger (1832-1917), a German doctor and hygienist is thought to be the first scientist to put forward the idea of human pheromones. He called the manthropines. He said they were lipophilic compounds associated with skin and follicles that mark the individual signature of human odors. Lipophilic compounds are those that tend to combine with, or are capable of dissolving in lipids. Researchers in the University of Chicago claimed that they managed to link the synchronization of womens menstrual cycles to unconscious odor cues. The head researcher was called Martha McClintock, hence the coined termthe McClintock effect. When exposing a group of women to a whiff of sweat from other women, their menstrual cycles either accelerated or slowed down; depending on when during the menstrual cycle the sweat was collected before, during or after ovulation. The scientists said that the pheromone collected before ovulation shortened the ovarian cycle, while the pheromone collected during ovulation lengthened it. Even so, recent analyses of McClintocks study and methodology have questioned its validity. There are four principal kinds of pheromones: Releaser pheromones they elicit an immediate response, the response is rapid and reliable. They are usually linked to sexual attraction. Primer pheromones these take longer to get a response. They can, for example, influence the development or reproduction  physiology, including menstrual cycles in females,  puberty, and the success or failure of pregnancy. Signaler pheromones these provide information. They may help the mother to recognize her newborn by scent (fathers cannot usually do this). Modulator pheromones they can either alter or synchronize bodily functions. Usually found in sweat. There are differences between men and women in the types of glands, secretions and even microbial flora present in the axillary environment, suggesting a sex-specific role. Most of these glands do not become active until after puberty, suggesting a role in sexual communication. (Hays, 2003) Pheromone-like compounds are also found in salivary, seminal and urine secretions, but studies tend to focus on the most accessible: axillary sweat. Jacob (2000, 2001) found increased physiological effects, only noticed a positive increase in mood and increased arousal in women when the test administrator present was male. Men were unaffected by the sex of the tester, but had slightly less effects than females overall. They concluded that pheromones are incredibly context dependent. Humans must integrate many different brain functions to affect arousal and mood. Psychologists Rachel Herz and Estelle Campenni were just getting to know each other, swapping stories about their lives over coffee, when Campenni confided something unexpected: She was living proof, she said, of love at first smell. I knew I would marry my husband the minute I smelled him, she told Herz. Ive always been into smell, but this was different; he really smelled good to me. His scent made me feel safe and at the same time turned on—and Im talking about his real body smell, not cologne or soap. Id never felt like that from a mans smell before. Weve been married for eight years now and have three kids, and his smell is always very sexy to me. RESEARCH In the now famous T-shirt experiments it was shown that specific women chose as most sexy and pleasant smelling T-shirts belonging to men who had immune systems that were different from their own. Because we all possess different MHC genes (and body-odor), for every woman a different set of men will be delicious smelling and others wont be. Theres no Brad Pitt of body odor! A womans nose not only responds to a mans body-odor in terms of his biological suitability, women actually find how a man smells to be the most important factor in their sexual attraction. In two large studies were conducted to examine how important various physical and social status factors were for men and women when choosing a sexual partner, we discovered that above all other physical characteristics, women ranked a mans scent as the most important feature for determining whether she would be sexually interested in him. How a man smelled was also more much important than any social status factor. And of all physical characteristics women preferred a man to be better than average in his body-odor than anything else. Women also found men who smelled great due to the fragrance they wore irresistible. In the words of one respondent: If Im with a guy who smells really good, nothing else about him seems to matter. Among heterosexual couples, similar MHC profiles spell relational difficulty, Christine Garver-Apgar, a psychologist at the University of New Mexico, has found. As the proportion of MHC alleles increased, womens sexual responsiveness to their partners decreased, and their number of sex partners outside the relationship increased, Garver-Apgar reports. The number of MHC genes couples shared corresponded directly with the likelihood that they would cheat on one another; if a man and woman had 50 percent of their MHC alleles in common, the woman had a 50 percent chance of sleeping with another man behind her partners back. You encounter a particular smell, and it immediately transports you back to an earlier time and to a pleasant memory. A recent feature in the Association of Psychological Sciences’ Observer discusses the connection. Researchers have discovered that there is a strong connection between smells, emotions and early life experiences. In fact, there is a strong relationship between certain smells experienced very early in life, typically before age 5, that will trigger pleasant feelings and memories. This is particularly true for odors that we don’t smell every day. The reason for these associations is that the brain’s olfactory bulb is connected to both the amygdala (an emotion center) and to the hippocampus, which is involved in memory. And, because smells serve a survival function (odors can keep us from eating spoiled or poisonous foods), some of these associations are made very quickly, and may even involve a one-time association. But even in adulthood, we can easily make associations between smells and memories. You might draw a connection between a certain perfume or cologne and a first encounter with a friend or lover, or the scent of a certain food may transport you back to the first time you ate it. Among heterosexual couples, similar MHC profiles spell relational difficulty, Christine Garver-Apgar, a psychologist at the University of New Mexico, has found. As the proportion of MHC alleles increased, womens sexual responsiveness to their partners decreased, and their number of sex partners outside the relationship increased, Garver-Apgar reports. The number of MHC genes couples shared corresponded directly with the likelihood that they would cheat on one another; if a man and woman had 50 percent of their MHC alleles in common, the woman had a 50 percent chance of sleeping with another man behind her partners back. SURVEY A survey was conducted. The hypothesis was â€Å"Scent Attracts Attention†. A sample of 30 teenagers from the age 17-21 out of which 15 were females and 15 were males. Each one of them a questionnaire consisting of 17 questions. Some questions were ranged from 1- 5 and some were yes, no or may be. All the questions were given a score and accordingly the score was found out. The following were the questions given to the subjects. QUESTIONNAIRE Q1. How likely are you to initiate a conversation with a stranger on the basis of good fragrance that he/she is wearing? Very unlikely Very likely 1 2 3 4 5 Q2. How likely are you to avoid having a conversation if the other person has a bad breath? Very unlikely Very likely 1 2 3 4 5 Q3. Is good fragrance an important factor in framing first impression? Yes No Q4. Would you consider going for an aroma therapy? Yes No Q5. Do advertisements about perfumes or deodorants urge you to buy them? Yes No Q6. Have you ever been attracted to a person because of the way they smell? Yes No May be Q7. Do you feel that putting an external fragrance affects your self-esteem? Yes No May be Q8. What do you prefer, natural body odour or external fragrance? Natural odour or External fragrance Q9. Do you feel men and women have different body odours? Yes No May be Q10. Have you ever purchased body fragrances in order to improve your interpersonal relationship? Yes No Q11. How conscious are you about your body odour and its impact? Very unconscious Very conscious 1 2 3 4 5 Q12. Does deodorant/perfume attract people? Yes No Q13. How frequently do you use deodorants/perfume in a day? Never Once twice every few hours Q14. While travelling, can you tolerate other people’s body odour? Yes No Q15. Would you ever use external fragrances as a substitute to showering? Yes No Sometimes Q16. Do you buy soaps, body wash or talcum powder to help you enhance your body odour? Yes No May be Q17. Would you use gender specific deodorants/perfumes? Yes No QUESTIONNAIRE SCORING Q1. How likely are you to initiate a conversation with a stranger on the basis of good fragrance that he/she is wearing? Very unlikely Very likely 1 2 3 4 5 Q2. How likely are you to avoid having a conversation if the other person has a bad breath? Very unlikely Very likely 1 2 3 4 5 Q3. Is good fragrance an important factor in framing first impression? Yes (5) No (1) Q4. Would you consider going for an aroma therapy? Yes (5) No (1) Q5. Do advertisements about perfumes or deodorants urge you to buy them? Yes (5) No (1) Q6. Have you ever been attracted to a person because of the way they smell? Yes (5) No (1) May be (3) Q7. Do you feel that putting an external fragrance affects your self-esteem? Yes (5) No (1) May be (3) Q8. What do you prefer, natural body odour or external fragrance? Natural odour (1) or External fragrance (5) Q9. Do you feel men and women have different body odours? Yes (5) No (1) May be (3) Q10. Have you ever purchased body fragrances in order to improve your interpersonal relationship? Yes (5) No (1) Q11. How conscious are you about your body odour and its impact? Very unconscious Very conscious 1 2 3 4 5 Q12. Does deodorant/perfume attract people? Yes (5) No (1) Q13. How frequently do you use deodorants/perfume in a day? Never (1) Once (2) twice (3) every few hours (5) Q14. While travelling, can you tolerate other people’s body odour? Yes (1) No (5) Q15. Would you ever use external fragrances as a substitute to showering? Yes (5) No (1) Sometimes (3) Q16. Do you buy soaps, body wash or talcum powder to help you enhance your body odour? Yes (5) No (1) May be (3) Q17. Would you use gender specific deodorants/perfumes? Yes (5) No (1) Classification done according to the scores is the following: 17-34: Not attracted to scent at all 35-52: A little attracted towards scent 53-70: Moderate attraction towards to scent 71-85: High attraction towards scent The total score of females was 767. The total score of males was 792. The total score was 1559. The highest score one could get was 85. The lowest score one could get was 17. The highest total score could be 2550. The lowest total score could be 510. TOTAL No attraction towards scent: 0 A little attracted towards scent: 16 Moderate attraction towards to scent: 12 High attraction towards scent: 2 The conclusion of the survey was that there is little or moderate attraction towards scent. The hypothesis was proved correct, scent does attract attention. Males are attracted to scent more than females. References: www.psychology today.com www.wikipedia.com