Pheromones - and human sexual behaviour (attraction)

Pheromones definition

• A pheromone is a chemical substance produced and released into the environment by an animal affecting the behavior or physiology of others of its own species.  ​ ​

• Although pheromones are known to play a significant role in signalling between members of the same species among animals to affect various behaviours, it is not clear that this is also true in humans

• Mammals have a separate structure called the vomeronasal organ (VNO) which connects to a special region of the brain called the accessory olfactory bulb. This region is adjacent, but separate to, the main olfactory bulb.​ 

• Humans do not have either the VNO or the accessory olfactory bulb ​

• human fetuses do have the accessory olfactory bulb but it shrinks and disappears after birth. ​

Potential Pheromones

• Androstadiene (AND)- Found in male semen and sweat.​ 

• Estratraenol (EST) - Found in female urine.​

Zhou et al (2014) - true experiment aim

to see if androstadienone and estratetraenol influenced human sexual behaviour.

Zhou et al (2014) - procedure

• Sample: four groups of healthy non-smokers, including 24 heterosexual males, 24 heterosexual females, 24 homosexual males and 24 bisexual or homosexual females.

• presented a point-light walker task (PLW), a set of dots that move in a way which represents the properties of human motion. 

• asked to observe the stick figure in motion and to identify its sex.

• They performed the task at around the same time of the day on three consecutive days while being continuously exposed to either androstadienone mixed with cloves, estratetraenol mixed with cloves, or a control solution, also mixed with cloves.

• participants only carried out the task while smelling one of the solutions each day (repeated measures design).  The scents were counterbalanced to control for order effects. 

Zhou et al (2014) - results

• heterosexual females and gay males were exposed to AND, had higher rate of identifying the stick figure as “masculine” than the control group. 

• AND had no significant effect on heterosexual men or lesbian women.

• smelling EST systematically biases heterosexual males toward perceiving the walkers as more feminine.

• effect was not statistically significant in bisexual and lesbian women.