Revise Hormones, pheromones and behaviour for IB Psychology (1.2)

Hormones are chemical messengers produced by the glands of the endocrine system and secreted into the bloodstream, which carries them to target cells that have matching receptors. Unlike neurotransmitters — which act almost instantly across a synapse over a tiny distance — hormones act more slowly but their effects last longer and reach the whole body. A key nuance examiners like to see: hormones do not simply CAUSE a behaviour like a switch; they raise the PROBABILITY that a behaviour occurs in response to a stimulus. That framing keeps you clear of crude biological determinism.

Cortisol is a steroid hormone released by the adrenal glands through the hypothalamic–pituitary–adrenal (HPA) axis when we face a stressor. In the short term it mobilises energy, but its relationship with memory is dose-dependent: moderate, brief rises can sharpen memory, whereas prolonged or high levels can impair the retrieval of declarative memories. This is why chronic stress is linked with forgetfulness and difficulty recalling learned material.

Newcomer et al. (1999) tested this experimentally. AIM: to investigate the effect of raised cortisol on verbal declarative memory. PROCEDURE: in a controlled design, participants took tablets over several days — a high dose of cortisol (roughly the level of a major stressor), a low dose, or a placebo — then completed a verbal recall task. FINDINGS: the high-dose group performed significantly worse at recall than the low-dose and placebo groups, and their memory returned to normal after the treatment stopped. LINK TO BEHAVIOUR: because the design manipulated cortisol directly, it supports a causal claim that this hormone impairs the behaviour of remembering — not merely that stress and forgetfulness happen to co-occur.

Oxytocin is produced in the hypothalamus and released by the pituitary gland. It is associated with social bonding, and several studies suggest it increases interpersonal trust. Baumgartner et al. (2008) offers a strong worked case. AIM: to investigate oxytocin's effect on trust after a person's trust had been betrayed. PROCEDURE: in a double-blind design, participants inhaled either oxytocin or a placebo and then played a 'trust game' — investing money with a trustee — while receiving feedback that they had sometimes been betrayed, all inside an fMRI scanner. FINDINGS: after betrayal, placebo participants invested less (they became wary), but oxytocin participants kept investing at the same level, and showed reduced activity in the amygdala (a fear-processing region) and feedback-related brain areas. LINK TO BEHAVIOUR: this shows the hormone oxytocin changed trusting behaviour — participants who received it were less deterred by betrayal — with a plausible neural mechanism (dampened threat response).

Adrenaline (epinephrine) is released by the adrenal glands during stress or excitement, driving the fight-or-flight response. Beyond immediate survival, the arousal it produces helps CONSOLIDATE memories, making emotionally significant events more vivid and durable than neutral ones — the biological basis often invoked for 'flashbulb memories'.

Pheromones are chemical signals released by one individual into the environment that affect the behaviour or physiology of others of the same species. In insects and some mammals this signalling is well documented. In humans it is genuinely contested. A central anatomical problem is that the vomeronasal organ (VNO) — which detects pheromones in other mammals — appears vestigial (non-functional) in adult humans. Even so, researchers study 'putative' (potential, unproven) human pheromones such as androstadienone (AND), found in male sweat. The evidence remains mixed and inconclusive: results are inconsistent across studies and are often confounded by social cues or produced with unnaturally high chemical doses.

Hormones and pheromones are one strand of the biological approach; they sit alongside neurotransmitters, brain localisation and genetics. The exam skill you have practised here — describe a named study, then link it explicitly to behaviour, and evaluate its methodology and ethics — is the same skill every Paper 1 answer in this approach demands. Master the link, and the rest of the unit becomes a matter of swapping in the right study.