In the realm of psychology, hormones and pheromones play a crucial role in influencing behavior. This detailed study note will cover various aspects of hormones and pheromones, their functions, and their effects on behavior, as outlined in the Higher Level (HL) International Baccalaureate (IB) Psychology syllabus. We will delve into specific hormones like testosterone and oxytocin, explore the concept of pheromones, and review key studies that illustrate their impact on behavior.
Hormones are chemical messengers secreted by endocrine glands directly into the bloodstream. They regulate a wide array of bodily functions and behaviors by acting on distant target organs. Unlike neurotransmitters, which act quickly, hormones typically have longer-lasting effects.
Note
The pituitary gland, located at the base of the hypothalamus, is often referred to as the "master gland" because it regulates the secretion of other hormones.
Testosterone is a steroid hormone primarily produced in the testes in males and in smaller amounts in the ovaries in females. It is the key male sex hormone responsible for the development of secondary sexual characteristics and has been linked to behaviors such as aggression and competitiveness.
Example
Some research shows that males in prison for violent offenses have higher levels of testosterone than those convicted of non-violent crimes.
Aim: To investigate whether testosterone makes people less generous and less prosocial towards strangers.
Procedure: Participants were administered either testosterone or a placebo. They then participated in a game where they could choose to share money with strangers.
Results: Those who received testosterone were less generous and less likely to share money compared to those who received the placebo.
Conclusion: Elevated testosterone levels may reduce prosocial behavior and increase selfishness.
Oxytocin, often referred to as the "love hormone," is produced in the hypothalamus and released by the pituitary gland. It plays a significant role in social bonding, sexual reproduction, and during and after childbirth.
Example
Oxytocin is released in large amounts during childbirth to facilitate labor and is also released during breastfeeding to promote bonding between mother and child.
Aim: To investigate the relationship between oxytocin, massage, and sacrifice.
Procedure: Participants were divided into three groups: massage, rest, and control. After the intervention, they participated in a game where they could choose to share money with others.
Results: Those in the massage group showed higher levels of oxytocin and were more likely to share money compared to the control group.
Conclusion: Oxytocin may enhance prosocial behavior and willingness to sacrifice for others.
Pheromones are chemical substances secreted by glands that act outside the body to affect the behavior of other members of the same species. Unlike hormones, which are secreted internally, pheromones are detected through specialized sensory organs.
Note
To date, there is no conclusive evidence that the VNO or the accessory olfactory bulb exists in adult humans, although they are present in the developing fetus up to 18 weeks of gestation.
Research into human pheromones has focused on substances like androstadienone (AND) and estratetraenol (EST), which are believed to signal maleness and femaleness, respectively.
Example
Males and homosexual women should be attracted by EST, while women and homosexual men should be attracted by AND.
Aim: To investigate whether AND and EST function as human pheromones in terms of sexual attraction.
Participants: 24 adult heterosexual males, 24 adult heterosexual females, 24 adult homosexual males, and 24 adult bisexual or homosexual females.
Procedure: Participants were exposed to either AND, EST, or a placebo over three days. They then watched point-light displays of walking figures and had to identify the gender of the figures.
Results: Heterosexual males and homosexual females were more likely to identify the figure as female when exposed to EST, while heterosexual females and homosexual males were more likely to identify the figure as male when exposed to AND.
Conclusion: Pheromones may influence gender perception according to sexual orientation.
Aim: To investigate the effect of AND and EST on gender perception.
Procedure: Participants were exposed to AND or EST and then asked to identify the gender of faces shown in photographs.
Results: Exposure to AND and EST did not significantly alter gender perception.
Conclusion: The study challenges the notion that AND and EST function as human pheromones affecting gender perception.
Common Mistake
A common misconception is that pheromones have been conclusively proven to exist in humans. The evidence is still inconclusive, and more research is needed.
Aim: To investigate the link between stress (measured by cortisol levels) and obesity in macaque monkeys.
Procedure: A review of several studies examining the effects of social stress on cortisol levels and obesity in female macaque monkeys.
Results: Subordinate female monkeys had higher cortisol levels, more fat cells, higher cholesterol, and a greater risk of heart disease compared to dominant monkeys.
Conclusion: Social stress and elevated cortisol levels are linked to visceral obesity and related health issues in macaque monkeys.
Note
This study should only be used for HL Extension questions on Paper 1 Section B and not for questions specifically about human behavior.
Tip
An exam question on this topic is likely to be worded in a way that gives you some choice over how to answer, such as "Describe/Discuss the effect of hormones and/or pheromones on behavior." You do not necessarily need two studies per hormone; you could choose one study of a hormone and one study of a pheromone if you prefer.
Understanding the role of hormones and pheromones in behavior is crucial for a comprehensive grasp of biological psychology. Hormones like testosterone and oxytocin have profound effects on behavior, influencing everything from aggression to social bonding. While the existence and function of human pheromones remain debated, studies like those by Zhou et al. (2014) and Hare et al. (2017) provide valuable insights. Animal studies further highlight the complex interplay between biological factors and behavior, offering a broader perspective on the subject.