biological approach: hormones and pheromones and their effect on behaviour Flashcards
hormone
- chemical messenger that affects human behaviour
- secreted by the endocrine glands into the bloodstream which then distributes it around the body
- produce reactions in certain target cells with appropriate receptor sites for specific hormones
pituitary gland
- master gland
- major endocrine gland which regulates the secretion of all hormones
- found at the base of the hypothalamus
hormones vs neurotransmitters
- hormones act slowly and may take years to fully have an effect e.g. puberty involves the slow release of testosterone/oestrogen
- neurotransmitters act fast
sex hormones
- Testosterone and oestrogen are the male and female sex hormones which control primary and secondary sexual characteristics.
- They also regulate key milestones e.g. puberty, sperm production (testosterone), the menstrual cycle and menopause (oestrogen)
oxytocin
- cuddle/love hormone
- associated with feelings of trust, bonding, security
- made in the hypothalamus at the top of the brain stem
- secreted during childbirth and feeding
- thought to be an evolutionary mechanism allowing mother and baby to bond
- some researches shows that oxytocin can be released as a result of touch, music or exercise
study: Scheele et al 2012 AIM
to investigate the link between oxytocin and fidelity
study: Scheele et al 2012 PARTICIPANTS
- 86 heterosexual men; some single and some in a stable monogamous relationship
- Researcher administered either oxytocin or a placebo intra-nasally
- Subjects participated in 2 independent tasks
study: Scheele et al 2012 METHOD
- double blind independent measures design
- “stop-distance paradigm”
Subjects were positioned at one end of the room with their toes on the mark on the floor, while an attractive female experimenter was positioned on the other side of the room.
The subject was then required to move slowly towards the female experimenter and stop at a distance that made him feel slightly uncomfortable (too close).
The experimenter maintained the same appearance over all the trials. - “approach/avoidance task”
Subjects viewed a series of pictures on a screen with their head positioned on a chin rest at a viewing distance of 50cm. Pictures were flashed for 2 seconds each.
There were 4 types of pictures shown in random order: positive social (attractive women), positive non-social (beautiful landscapes), negative social (mutilations), and negative non-social (dirt).
All participants had a joystick they were instructed to pull if they liked the picture (the picture’s size consequently increased) and push if they didn’t like it (the picture’s size consequently reduced).
study: Scheele et al 2012 RESULTS
1st task: showed that oxytocin stimulated men in a monogamous relationship, but not single ones, to keep a great distance between themselves and an attractive woman.
Men with oxytocin kept a further distance away than the men with placebo
2nd task: showed that the only group of pictures affected by oxytocin and relationship status was the positive social group. Specifically, participants who received oxytocin had slower reaction time in response to these pictures, but only if they were in a relationship.
Men in relationships had a slower reaction time than single men
study: Scheele et al 2012 CONCLUSION
This study supported the theory of hormones on the effect of human behaviour since the oxytocin had positively affected fidelity (being faithful/loyal) in relationships
study: Scheele et al 2012 STRENGTHS
- Double blind design, lower chance of researcher bias
- Independent measures design, less time consuming, costs less, increases external validity as more participants are used
- No apparent physical (oxytocin has no known dangerous side effects) or psychological (relation to fidelity) effects
study: Scheele et al 2012 WEAKNESSES
- Independent measures design, may lead to differences in the groups’ results
- Distance between participants and female may not be a result of oxytocin, depends on person and their comfort level (confounding)
study: Morhenn et al (2008) AIM
to investigate the relationship between oxytocin, massage, and monetary sacrifice
study: Morhenn et al (2008) PARTICIPANTS & METHOD
- 96 students, mean age = 22.3 years, 53% female, 47% male, were randomly allocated to 1 of 3 conditions:
- Massage and Trust group (MT) → received a 15 minute back massage followed by a trust game in which each PPS was a decision maker and had to decide whether to match the donations made by another player (each had been given $10), which was measured as monetary sacrifice made per participant
- Rest and Trust group (RT) → PPS asked to rest for 15 minutes and then to play the trust game
- Massage only group (M) → received a 15 minute massage
- The PPS’ blood was sampled before and after the procedure to compare the pre-experiment and post-experiment oxytocin levels
study: Morhenn et al (2008) RESULTS
- The MT group showed the biggest increase in oxytocin levels (16%) than the RT group.
- The MT group also sacrificed 243% more money than the RT group with women showing higher levels of oxytocin and more monetary sacrifice overall than men.
- M group showed no difference in oxytocin levels, possibly because they were not asked to engage in a trust game (massage alone wasn’t enough to increase oxytocin).
- RT group showed decreased oxytocin levels compared to the other 2 groups
study: Morhenn et al (2008) CONCLUSION
massage followed by a trust game appears not only to increase oxytocin levels but also to predict the direction of monetary sacrifice (increasing oxytocin levels is matched by increasing monetary sacrifice)
study: Morhenn et al (2008) STRENGTHS
- Using the M condition as a control ensured that the researchers were able to demonstrate that the combination of touch and trust raised oxytocin and resulted in monetary sacrifice
- Using objective measures e.g. MRS increases the reliability and scientific nature of the findings
study: Morhenn et al (2008) WEAKNESSES
- Attempting to operationalise trust in an artificial game is difficult as this is a subjective variable and may fluctuate according to mood or situation
- Conducted the study in an individualistic culture, a collectivist culture may view trust differently
hormones critical thinking
- the reductionist nature of attributing complex human behaviours to a single hormone; the indirect way in which hormones are often measured, the difficulty of measuring hormones in a naturalistic setting; when not experimental, then correlations are drawn which may be based on assumptions
pheromone
- a chemical substance secreted from glands to act outside of the body (unlike hormones)
- released into the environment by animals and it affects behaviours of others of its own species
pheromones topic (animals, VNO)
- first research was done on animals
- animals use pheromones for mating and territoriality
- not found in humans yet
- under controlled conditions, some chemicals mailed humans to show behaviours similar to animals
- mammals use VNO to detect pheromones
- VNO does not exist in humans
- without the anatomical ability to detect pheromones, it is unclear how pheromones would affect humans behaviour
androstadienone (AND)
- potential human pheromone
- a human steroid present in male semen and sweat
- heightens sympathetic arousal, alters cortisol levels, promotes positive mood state in females
- activates the hypothalamus in heterosexual females and homosexual males, but not in homosexual females or in heterosexual males
study: Zhou et al (2014) AIM
to investigate if androstadienone influenced human sexual behaviour
study: Zhou et al (2014) METHOD
- He carried out an experiment with a sample of heterosexual men & women, gays and lesbians.
- Participants watched stick figures walking on a screen and then were asked to guess the gender of the stick figure. - The participants were exposed to the smell of cloves when watching the screen.
- In the experimental condition, the cloves were mixed with androstadienone and in the control condition, only cloves were used.
study: Zhou et al (2014) RESULTS
- when heterosexual females and gay men were exposed to androstadienone, they had a higher rate of identifying the stick figures as “masculine” than the control group.
- Androstadienone had no significant effect on men or lesbian women.
study: Zhou et al (2014) CONCLUSION
Androstadienone could be a pheromone which influences mating behaviour in humans
study: Zhou et al (2014) STRENGTHS
- Standardised procedure → same point-light figures were viewed across the conditions, ensuring a reliable measure of control
- Using point-light figures rather than photos of real humans helps to eliminate confounding variables of individual differences regarding to who/what is attractive
study: Zhou et al (2014) WEAKNESSES
- Use of synthetic AND doesn’t reflect how the steroid is secreted in real-life situations → impairs external validity
- Task lacks ecological validity as it was artificial and doesn’t consider other variables that may result in judgements pertaining to masculinity or femininity
study: Savic et al (2005) AIM
to investigate whether human pheromones exist, and how they affect the brain
study: Savic et al (2005) METHOD
- 24 men and women
- PPS were exposed to the smell of 2 chemicals, nearly identical to the smell of testosterone and oestrogen
- As they smelled the chemicals, their brains were scanned using a PET machine
study: Savic et al (2005) RESULTS
- Hypothalamus became activated in men when they smelled oestrogen, activated in women when they smelled testosterone
- Hypothalamus is linked to sexual behaviour and is not normally activated by ordinary smells
- Hypothalamus of gay men lit up when they smelled the male hormone, but they did not respond to the female hormone
study: Savic et al (2005) CONCLUSION
suggests that sex pheromones exist in humans and they may influence sexual behaviour
study: Savic et al (2005) STRENGTH
Lab experiment- well controlled, cause-and-effect relationship between the chemical scent (IV) and hypothalamus activity (DV)
study: Savic et al (2005) WEAKNESSES
- Small sample size- low generalisability
- Unclear how these pheromones would influence behaviour in the real world
pheromones critical thinking
- There are several problems with the pheromone arguments.
- First, the human sense of smell is very complex, which makes it very difficult to see how pheromones would work in humans.
- Many body odours are actually not caused by secretions, but by bacteria that mix with our secretions - for example, in the armpits.
- However, about 20% of the population does not have this bacteria and thus does not create the same scent.
- This makes a universal finding of pheromones a bit less likely.
- In addition, culture plays a key role in our sense of smell - we learn what smells bad and what smells good.
- This could potentially be a confounding variable when trying to determine the role of pheromones on behaviour.
- Finally, much of the research is highly artificial and has not been sufficiently replicated.
