Leiden Psychology Blog

Sexual pheromones: myth or truth?

Sexual pheromones: myth or truth? Neon love by BSchwehn

Valentine’s Day is the day of love. Especially nowadays, pheromones are advertised and sold as cologne or perfume in order to stimulate attraction between people. However, the question is: do sexual pheromones really exist, and how good are they?

Pheromones are chemosignals transmitting gender-specific information. The most widely studied human pheromone is AND (Δ4,16-androstadien-3-one) which is secreted by axillary sweat. There are higher concentrations of AND in male than in female axillary sweat. These findings led some researchers to the idea that AND is involved especially in human attraction. Support for this hypothesis comes from Saxton and colleagues, who found in 2008 that young females, when exposed to AND, rate males at a speed dating event significantly more attractive, than females exposed to the control substance. Despite this evidence, many scientists such as the olfaction expert Richard Doty in his book The Great Pheromone Myth,  claim that, unlike insects, mammals do not have pheromones and that these chemosignals don’t play a role in mammalian behavior and reproductive processes.

Other scientists, such as Tristram D. Wyatt, say that mammals are likely to use pheromones; however, so far no pheromones have been conclusively identified, despite stories in the mass media.

What is clear to me from my direct experience, working with my students Laura Steenbergen and Annelies de Haan on a project investigating the effect of AND on attention, is that pheromones are “tricky” chemosignals that are effective only in particular groups of people, or when specific conditions are met:

  • The person should not be aware of the pheromones. 10% of the population can be aware of them in terms of reporting a “bad/animal/sweat-like smell”.
  • Women should not be suffering from a cold or allergy symptoms, and not be using oral contraceptives. These women are particularly sensitive to pheromones in the late follicular phase of their menstrual cycle (which corresponds to the fertile period in women).
  • Gay men are more affected by pheromones than heterosexual men.
  • Visual attractiveness plays a key role. AND is effective in average good looking men but not in men with unpleasant look.

Pheromones are NOT really effective:

  • In heterosexual men
  • In homosexual women
  • In women who are using oral contraceptives

In sum, getting back to the question: yes, pheromones may exist, but they are good only under very restricted circumstances. For sure, pheromones are not miracle perfumes. So, for Valentine’s Day, until more information will be available on pheromones, is better to stick to the traditional red roses and heart-shaped chocolates.

 

This blog was also published in Dutch in de Volkskrant on 09-02-2013 under the title of 'Romantiek met een vleugje zweetspray'.

7 Comments

Fernand Vedrenne
Posted by Fernand Vedrenne on February 17, 2013 at 06:44

There are very complex sensory evaluation techniques that are statistically valid which allow you to determine the perceptual threshold of different stimuli, this is the intensity at which the stimuli are perceived and what percentage of your panel is perceiving the stimulus at a given intensity. AND does have a sweaty-animal-like smell, so when people report such smell, you know they are reporting AND.
I think you are being very hard on this study, “direct experience”  for any researcher is actually their research. Don’t get confused buddy, this is just a blog. If you want to dig deeper into the matter and judge the methodology, I’m sure that you can find and read Dr. Colzato’s papers online. I don’t think that you can draw such conclusions without really knowing what she and her team did.

justthinkingabit
Posted by justthinkingabit on February 17, 2013 at 06:24

Of course there are things that can have an effect on your brain without your perceiving them. The evidence cited in this article is “direct experience”, which to me says very little. What exactly is used to discern this 10% of people that perceive the bad smell which is supposed to be pheromone associated, from people who just perceive a bad smell? This is not made clear.
Furthermore yes it is fine and good to state contrasting evidence from other researchers. But from how this article is written, it reads as if the author is at first certain of AND being the known pheromone. This is followed by a statement that reads “however, so far no pheromones have been conclusively identified”, which is actually refuting an article by another writer. So here no the author isn’t reporting contradicting evidence, but rather just contradicting herself and another author.
What does invalidate this study as a science is the lack of evidence given for any of the larger statements made (“direct experience” does not qualify for explaining differences between homosexuals and heterosexuals), as well as the inability to define from the outset what a pheromone is and even if have concretely identified one.
I’m guessing this comment also will be deleted, but I would prefer someone just try and explain to me actually what a pheromone is with a scientific method in mind.

Fernand Vedrenne
Posted by Fernand Vedrenne on February 16, 2013 at 21:54

Would it be correct to rephrase this as follows? If the AND concentration is above the perceiver’s olfactory threshold, then the subject in question would be put off by the intense smell of AND, thus overthrowing AND’s effect on arousal and attraction, whereas if the concentration of the pheromone is under the threshold, it can have an arousal effect.
For those people stating that this is pseudoscience, I would just like to comment that the fact that you cannot perceive a substance with your senses doesn’t mean that it does not have an effect on your brain. Under the experimental conditions undertaken by Dr. Colzato’s research group, only 10% of the individuals were able to perceive AND, this means that the concentrations used were well under the population’s olfactory threshold (the concentration at which 50% of the population can actually smell a substance). Additionally, I have to mention that drawring conclusions from a random experiment that involves sexual behavior is a very difficult task due to the huge variability there is within the population. therefore, it is very responsible and ethical from Dr. Colzato’s team to state the limitations of their study and to report other fellow researcher’s contradicting evidence so that the trained reader is able to find trends by himself instead of taking these results as hard evidence. Remember that science is ever-changing.

Bryant Jongkees
Posted by Bryant Jongkees on February 16, 2013 at 16:37

I think this article does provide interesting information on pheromones, especially because their effect is often ‘mythical’, exaggerated and this article nuances their positive function, but still informs us that their effects aren’t nonexistent.

In response to justthinkingabit’s criticism on the supposed contradictory ‘working’ vs ‘not working’, I think I understand the confusion. Since pheromones are most commonly known for somehow increasing attraction, they could be said to be ‘not working’ when they do not increase attraction. In that sense, when you can actually smell them they are ‘not working’ to increase attraction, their sensationalized function. In more technical terms they are still having an effect and can be seen as still working, but in the opposite direction. Thus the confusion lies in using the term ‘working’ when they have ‘attraction increasing’ effects and ‘not working’ when they do not have a positive effect, so it’s usage is in some places informal and in some places technical.

This usage of terms in no way invalidates these findings as science. This article subjects a myth to testing to determine the truth of its sensationalized function.

justthinkingabit
Posted by justthinkingabit on February 16, 2013 at 13:58

They ARE still working, but just working as a “turn off” then, even if you smell them. Chemicals can work in a negative fashion . . .  of course it means it is still working.

Lorenza Colzato
Posted by Lorenza Colzato on February 15, 2013 at 09:49

Pheromones are not working if you can smell them because they are sweat-like smell. Accordingly, instead of working as a “turn on”, they are working like a “turn off”.

Meriem Manai
Posted by Meriem Manai on February 15, 2013 at 09:35

Why are pheromones not working if you can smell them?

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