Unit 2:Biological Level of

AnalysisSession 9

‘All that is psychological is first physiological’

A Quick Recap

What are hormones?

Hormones are chemicals that affect behaviour.

They are produced by the glands that make up the endocrine system

Hormones are a contributing factor to behavior.

Hormones and Neurotransmitters

Neurotransmitter: A chemical in the synapse that transmits signals between neurons

Hormone: A chemical secreted by an endocrine gland. Travels through the bloodstream. Usually involved in longterm functioning of the body.

Similarities & Differences between neurotransmitters and hormones

Similarities DifferencesChemicals are stored and released Neurons communicate with adjacent

neurons; hormones messages are sent long distances

Release of chemicals is due to stimulation

Neural messages induce rapid response compared to hormones which have slower messages which tend to be long term

Many different hormones & neurotransmitters

Neural messages can be directed as observed in behaviour; hormonal messages are primarily involuntary (cannot be directed)

Outline the similarities and differences between neurotransmitters and hormones

Last session’s Journal Entry

Today’s learning outcome

Explain, using examples, functions of two hormones in human behaviour

Explain, using examples, functions of two hormones in human behaviour

1.Oxytocin2.Melatonin3.Cortisol

Examples of hormones

Produced by the hypothalamus & released into bloodstream by pituitary gland

Plays role in inducing labour & lactation Released with touches & hugs Associated with bonding between mother &

child

Oxytocin

Also associated with bonding between lovers

Has been called the “love hormone” as it seems to be such an effective mediator of human social behaviour

Oxytocin

Watch the video on Oxytocin the “love hormone”

Take notes

Oxytocin

Oxytocin has been linked to trusting other people

Experimental manipulation of oxytocin levels has shown increase in trust

According to evolutionary psychologists, trust is an important social tool in the relationship between humans

Research is being carried out to see whether people suffering from social anxiety may benefit from doses of oxytocin

Oxytocin & Trust

Trust is an adaptive mechanism as is helps humans to form meaningful relationships at a personal and professional level

Betrayal disrupts bonds of trust and may result in avoidance of person who has betrayed you

Learning who to trust and who to avoid is important for survival and well-being

Humans should be able to move on after betrayal if mental well-being are to be preserved

Oxytocin could play a role in reducing fear reactions via the amygdala that may arise as a consequence of betrayal

Oxytocin & Trust: an evolutionary perspective

Aim To investigate role of oxytocin after breaches of trust

in a trust gameProcedure: Participants played a trust game used by economists

and psychologists to study social interaction The “investor” (player 1) receives a sum of money

and must decide whether to keep it or share it with a “trustee” (player 2)

If sum is shared sum is tripled Then player 2 (trustee) must decide if this sum

should be shared (trust) or kept (violation of trust)

Oxytocin & Trust: Baumgartner et al. (2008)

Procedure fMRI scans were carried out of 49 participants They recieved either oxytocin or placebo via a

nasal spray Participants played against different trustees

in the trust game and against a computer in a risk game

In 50% of games trust was broken They received feedback on this from

experimenters during the games

Oxytocin & Trust: Baumgartner et al. (2008)

Results

Oxytocin & Trust: Baumgartner et al. (2008)

Placebo Group Oxytocin GroupLess likely to show trust after feedback on betrayal. They invested less.

Continued to invest at similar rates even after recieving feedback on a breach of trust

fMRI scans showed decreases in responses in amygdala and caudate nucleus in Oxytocin group.Amygdala involved in emotional processing & has many oxytocin receptorsCaudate nucleus associated with learning & memory and plays a role in learning to trust

Oxytocin could explain why people are able to restore trust and forgive in long term relationships

Scanner research merely maping brain activity but nothing definite can be said about what it really means with current technology

Giving oxytocin like this in an experiment may not reflect natural physiological processes. Function of oxytocin very complex and it’s too simplistic to say it’s the “trust hormone”

Evaluation: Baumgartner et al. (2008)

Journal Entry

Summarise Baumgartner et al (2008)

You must include:1. Procedure2. Findings 3. Evaluation of study

Production of melatonin by pineal gland is stimulated by darkness and inhibited by light

Melatonin levels in bloodstream peak in middle of night and gradually decrease towards morning

Melatonin

In temperate climates when the days get shorter and winter approaches, the earlier onset of darkness means we become tired earlier

Until recent history, humans in temperate climates had up to 18 hours of darkness in winter months

The use of artificial lighting has increased awake time dramatically

Melatonin

Melatonin release correlates with the circadian rhythm (the biological clock that is based on a 24 hour day/night cycle)

It is suggested that taking melatonin in the early evening may improve one’s ability to fall asleep

Through study of melatonin researchers hope to find a solution for those who suffer from insomnia and jet lag

Melatonin

Melatonin & Circadian Rhythm

Rosenthal (1987)

Evidence to suggest that higher levels of melatonin contribute to seasonal affective disorder (SAD)

SAD= a subcategory of depression that is characterised by sleepiness, cravings for carbohyodrates & lethargy

Reduced levels of sunlight in autumn and winter believed to disrupt circadian rhythm is certain people leading to this depression

Perhaps why we see higher levels of SAD in Scandinavia

Melatonin & SAD

As increased sunlight improves the symptoms, phototherapy (prolonged exposure to bright light) often main treatment for people with SAD

Despite some claims success, there is lack of definitive evidence of its effectiveness One has to be careful about seeking quick solutions to complex questions

Melatonin & SAD

Watch the video on SAD

Melatonin & SAD

Journal Entry

What is melatonin?

What is its link with SAD?

How might SAD be treated?

More on hormones and behaviour

Cortisol

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