🧬 Hormones and Behaviour

📘 Key Concepts and Definitions

Term	Definition
Hormone	Chemical messenger secreted by endocrine glands that travels in the bloodstream to regulate physiology and behaviour.
Endocrine system	Glandular system (pituitary, adrenal, thyroid, gonads) that secretes hormones directly into the blood.
Target cell	A cell that has receptor sites specific to a particular hormone.
Feedback loop	Regulatory system that controls hormone levels to maintain homeostasis.
Oxytocin	A peptide hormone linked to bonding, trust, and social attachment.
Cortisol	Glucocorticoid stress hormone that regulates metabolism, immune function, and memory.
Testosterone	Sex hormone associated with aggression, dominance, and reproduction.

📌 Hormonal Mechanisms

• Hormones act slowly but have long-lasting effects compared to neurotransmitters.
  
• They bind to specific receptors on target organs or brain structures, altering gene expression or neural activity.
  
• They influence behavioural patterns such as aggression, stress, and bonding.
  

🧠 Key Studies

1. Newcomer et al. (1999) — Cortisol and Verbal Memory

• Aim: To test the effect of stress hormones on cognitive performance.
  
• Method: Double-blind experiment; participants received either a high cortisol dose, low dose, or placebo.
  
• Results: High cortisol impaired performance on verbal declarative memory tasks.
  
• Conclusion: Stress levels of cortisol negatively affect hippocampal function and memory.
  
• Evaluation:
  
  • ✅ High internal validity (controlled experiment)
    
  • ❌ Low ecological validity (artificial stress induction)
    
  • ✅ Ethical safeguards (short duration, informed consent)
    

2. Baumgartner et al. (2008) — Oxytocin and Trust

• Aim: To investigate the role of oxytocin in trust and social risk-taking.
  
• Method: fMRI study using a “trust game.” Participants received intranasal oxytocin or placebo before playing.
  
• Results: Oxytocin increased trust even after betrayal. Activity decreased in amygdala and caudate nucleus.
  
• Conclusion: Oxytocin reduces fear and increases trust by inhibiting amygdala activity.
  
• Evaluation:
  
  • ✅ Neuroimaging evidence for biological basis of trust
    
  • ❌ Artificial task limits generalisability
    
  • ✅ Double-blind placebo control reduced bias
    

3. Dabbs et al. (1995) — Testosterone and Aggression in Prisoners

• Aim: To explore testosterone’s relationship with aggression.
  
• Method: Salivary testosterone measured in 692 male inmates.
  
• Results: Higher testosterone correlated with violent crimes and dominance-related behaviours.
  
• Conclusion: Testosterone is associated with dominance and aggressive behaviour.
  
• Evaluation:
  
  • ✅ Large sample size improves reliability
    
  • ❌ Correlational study (no causation)
    
  • ❌ Cultural and environmental influences uncontrolled
    

💡 TOK Links How far can we attribute behaviour to biological determinism? Does the presence of a hormone cause behaviour, or merely correlate with it? Can we “see” hormones’ effects, or do we infer them indirectly?

🌍 Real-World Connections Cortisol testing is used in occupational health and PTSD treatment. Oxytocin therapies are studied for autism and social anxiety. Hormonal insights help understand stress management and emotion regulation.

❤️ CAS Links Workshops or campaigns on stress management or mental health can link to cortisol and oxytocin research. Creativity projects: informational posters or infographics on “How Hormones Shape Emotions.”

🧪 IA Guidance\ Replicable experiments: effects of stress on memory recall or trust behaviour tasks. Ethics: informed consent, debriefing, minimal distress.

🧠 Examiner Tips\Always identify the hormone and the behaviour. Don’t confuse neurotransmission with hormonal action. For ERQs, discuss multiple hormones and link to localisation (amygdala, hippocampus).