Gender and Smell Recognition
There has been a significant amount of speculation about innate gender differences in thought, cognitive ability, and the relative strength of certain senses. One of area that has received some attention is the ability to smell. Anecdotal evidence suggests that women have a stronger ability to smell than men, as does significant prior research. This research study will examine the relative strength of the sense of smell of a group of men compared to a group of women. Each test group will consist of 20 subjects. The expectation is that the women, as a group, will have a statistically significant better sense of smell than the men. However, at the outset of this study, it must be noted that many factors other than gender are known to influence the sense of smell including overall health and age. This study did not control for those additional factors, which may help explain the study's results.
Literature Review
In many animal species, the sense of smell is critical to survival, helping them identify food, predators, and toxins, as well as aiding in communication (Zarzo, 2007). Therefore, understanding the sense of smell and how it works may be an important component in understanding animal behavior. Moreover, if there are gender differences in smell recognition, understanding the underlying mechanisms may help explain those differences. Selective protein receptors in the nose trigger a nervous signal processed by the brain (Zarzo, 2007). However, there are few details available about odorant-receptor interaction at the molecular level, which makes it difficult to hypothesize about why women would have a better sense of smell than men.
Despite this lack of underlying explanation, most people believe that women have more sensitive senses of smell than men. This belief has been verified in prior research. For example, in a 1993 study by Ship & Weiffenbach, which was designed to examine the impact of age on sense of smell, they found that females had higher scores on the University of Pennsylvania Smell Identification Test than males (1993). They also found other factors that impacted smell, such as illness, taking prescription medicine, and overall health (Ship & Weiffenbach, 1993).
One of the interesting facets about female superiority at odor recognition and recall is that researchers are not certain why women might have better senses of smell. Some have suggested that women might not actually have superior olfactory powers, but might be in-tune to other cues in the environment that assist them with smell recognition. However, Lehrner's research belies this suggestion. In a study testing men and women for odor recognition over long-term intervals, he found that women outperformed men (Lehrner, 1993). Moreover, he also used a signal detection methodology for recognition memory, which suggested that the olfactory superiority was probably due to sensory factors (Lehrner, 1993). However, that does not mean that cognition plays no role in sensory memory; Lehrner labeled the scents in his study and found that consistently labeled scents were more likely to be remembered than inconsistently labeled scents (1993).
One of the most interesting aspects of the gender differences in smell sensitivity is that men and women can be induced to be sensitive to s smell that they initially could not smell. Researchers found that induction of enhanced olfactory sensitivity is possible with a range of odorants. However, this enhancement was not possible in all groups. Instead, the increased sensitivity was observed only among females of reproductive age (Dalton et al., 2002). This research suggests that gender-based smell differences are also linked to age.
Moreover, it is important to realize that, while this sense of smell may not be as critical to modern humans in a modern world, there is probably an underlying genetic reason that women have an enhanced sense of smell when compared to men. After all, human beings are smelly creatures, something that may be forgotten in an era of soap, perfume, and deodorant. Humans produce stable odour signatures and other human beings are able to recognize them by sense of smell (Lenochova & Havlicek, 2008). Moreover, the ability to scent-recognize other human beings is impacted by other factors. "The capability of self, gender, kin and non-kin odour recognition plays a role in social interactions" (Lenochova & Havlicek, 2008). Therefore, gender differences in smell recognition may be linked to gender differences in bonding and recognition.
Of course, gender is not the only factor known to impact olfactory functioning. Instead, a host of other factors is either known to impact or suspected to impact one's sense of smell. For example, a study comparing people known to be at risk of developing Alzheimer's with a matched control group (matched for age, gender, education, and race) found that the at-risk group performed worse than the control group on several tests of smell (Schiffman et al., 2002). This was before any onset of disease, suggesting that genetic factors may play a role in olfactory sensitivity.
Another interesting facet of sense and memory is that women appear to have better sense memory on multiple levels, not just for smell. For example, women have better visual recognition memory for familiar objects than men (McGivern et al., 1998). There was a question of whether the gender difference was linked to greater verbal ability in females or greater compliance with task...
Researchers came to the conclusion that the gender difference in recognition memory is due to greater unconscious processing of environmental stimuli in females (McGivern et al., 1998).
Procedure
This experiment involved 40 participants, 20 male and 20 female. Each of the 20 males was asked to smell 3 dilution levels of perfume. Each of the 20 females was asked to smell 3 dilutions of cologne. The dilutions were labeled as 1, 2, or 3. Number one was the least diluted, containing 10 drops of water. Number two was in the middle, containing 15 drops of water. Number three was the most diluted, containing 20 drops of water. Those who were able to recognize the scent at a level 3 had the best ability to recognize scent, because 3 was the most diluted.
Methods
Each of the subjects was asked to sniff three vials containing a mixture of perfume or cologne and water and to determine whether or not they could identify a scent when smelling the mixture. The vials were labeled 1, 2, and 3 (lowest dilution to highest dilution). Males were asked to smell dilutions containing a perfume mixture, while females were asked to smell dilutions containing a cologne mixture. The participants were not informed of the numerical significance of the numbers. The results section reports the highest level of dilution identified by each of the test subjects.
Materials
The materials for this experiment were a sample of perfume, a sample of cologne, water, a dropper to ensure consistent measurement of water and cologne or perfume, and six vials labeled 1, 2, or 3. The perfume or cologne was diluted with the appropriate amount of water and placed in each of the vials, 1, 2, or 3 for both cologne or perfume. Those were all the materials needed to conduct the experiment.
Results
The results of the experiments are displayed in Table 1 (male) and Table 2 (female).
Subject No.
Dilution
1
2
2
2
3
2
4
3
5
1
6
1
7
2
8
3
9
1
10
1
11
2
12
2
13
3
14
3
15
1
16
2
17
1
18
3
19
2
20
1
Table 1: Male Results
Subject No.
Dilution
1
2
2
3
3
3
4
3
5
2
6
3
7
2
8
1
9
2
10
2
11
3
12
2
13
3
14
1
15
1
16
2
17
3
18
2
19
2
20
3
Table 2: Female Results
Prior to performing an analysis, there appears to be a difference between male and female scent recognition, because only three females were only able to recognize the scent at level one, while seven males were stopped at level one. Moreover, eight females smelled the scent at level three, while only five males smelled the scent at level three. These initial results, contained in Table 3, suggest a gender-based difference in scent recognition.
Dilution Level
Number of Males
Number of Females
1
7
3
2
8
9
3
5
8
Table 3: Dilution Levels, by Gender
However, an analysis of these results demonstrates that the differences do not reach statistical significance.
The t (38) = 1.47, which means the p>.05, so that the results of the analysis are not statistically significant. Therefore, while one can see that there was an observed difference in the differences between the genders in the ability to recognize smell, the results of the survey do not suggest that these differences are statistically significant.
Discussion
In most experiments, focusing on the results is the important part of the discussion session. Therefore, one must begin by addressing the fact that, although the results demonstrated the hypothesized gender difference in ability to recognize smell, the results were not statistically significant. There are a number of reasons those numbers might not be significant, even before considering the flaw in the design. First, there was no attempt to match the subjects on demographics such as health, age, or race; all factors that are believed to impact olfactory ability independent of age. Second, the study groups were relatively small, and it can be difficult to attain statistically significant results when working with such a small sample.
However, the real discussion has to involve an examination of the flaw underlying the entire research project. Males were asked to smell perfume samples, with the assumption being that men might be more in-tuned to smelling perfumes, which are scents that are…
