Biological approach - assumptions

What is the biological approach? The biological approach combines psychology and biology to provide physiological explanations for human behaviour. Biological psychology tries to explain how we think, feel and behave in terms of physical factors within the body.

Assumptions of the biological approach Evolutionary influences Localisation of Brain function Neurotransmitters These three things all have an effect on our personality and psychology Challenge: What do you already know about these three things?

Assumption 1: Evolutionary Influences What do you know about evolution? When have you come across it before? Do you think human behaviour has evolved? How would we know? Evolution is the change of a species over time Charles Darwin

Assumption 1: Evolutionary Influences Darwin’s theory of natural selection is based on three main assumptions. Only a small proportion of each generation survives to reproduce. Offspring are not identical to their parents, and so each generation has a degree of variation, and that at least some of this variation is heritable (can be passed on through genes). Some characteristics give the animal an advantage over others in the ability to survive and reproduce. Characteristics which give the animal a greater chance of survival and reproduction are adaptive.This is natural selection. If a characteristic has survived and been passed down through the generations, it must have been adaptive and have given the animal a survival advantage.

Assumption 1: Evolutionary Influences Natural selection Altruistic behaviour is an example of this – parents risk their lives to save the life of their offspring. Natural selection suggests that altruism is an inherited and adaptive trait because saving the life of offspring enhances the gene pool.

Assumption 1: Evolutionary Influences How could evolution explain a possible biological predisposition to fear snakes and spiders?

Assumption 1: Evolutionary Influences In practically every culture in the world, men prefer young rather than old women, women with wide hips and narrow waists, and women with full lips and large eyes. What could be the evolutionary explanation for this?

Assumption 1: Evolutionary Influences Full lips and large eyes are signs of youth. Younger women are more fertile. Men who have sex with young women are more likely to produce offspring. Narrow waists and wide hips are also signs of fertility and health.

Assumption 1: Evolutionary Influences Can you think of any other human behaviours that we could argue are “adaptive”? Love? Aggression? Intelligence?

Assumption 1: Evolutionary Influences Environment of evolutionary adaptiveness" (EEA). To understand the functions of the brain, we must understand the environment in which the brain evolved. Humans began evolving around 2 million years to around 100,000 years ago. Evolutionary psychologists argue that humans are adapted to the environment that our ancestors would have faced.

Assumption 1: Evolutionary Influences Those able to form alliances would survive in a complex social world Large brain size in comparison to body Look at the image above of what we believe life was life for our ancestors. What behaviour and traits would have been adaptive for early humans? Do we still have these traits today?

Assumption 3: Neurotransmitters Neurons are the cells which are found in the brain and nervous system. They work by sending chemical and electrical messages to each other.

Neurotransmitters

Assumption 3: Neurotransmitters The whole of the nervous system (including the brain) is composed of interconnected neurons. These are long thin cells that convey messages from one place to another. They can be smaller than 1mm, or longer than a metre! The brain contains billions of these neurons. Neurons pass messages from one neuron to the next via small gaps between the neurons called a synapse (20 mm wide). These messages are passed from neuron to neuron by chemicals called neurotransmitters, released from presynaptic vesicles. Neurotransmitters are chemical messengers that act between neurons within the brain. This allows the brain to process thoughts and memories.

Different neurotransmitters have different effects on us. http://imgur.com/xDQ B5fC

Assumption 2: localisation of brain function The two halves of the brain are called ____________ There are roughly ________ neurons in the brain and spinal cord. Behaviour can be explained in terms of different areas of the brain. Many different areas of the brain have certain functions. The cerebral cortex covers the surface of the brain (a bit like a tea cosy!) and is folded and grey in colour – this region is responsible for higher cognitive functions. hemispheres 100 billion

Assumption 2: localisation of brain function The cerebral cortex is divided into four areas. The most important is the frontal lobes deal with thinking and creativity. The parietal lobe receives sensory information such as temperature, touch and pain. The temporal lobes are responsible for memory processing, as well as processing auditory information. The final lobe is the occipital lobe which deals with vision and receives information directly from the eyes.

Assumption 2: localisation of brain function There are specific areas of the brain linked to the processing of language. In the middle of the 19th century, French neurosurgeon Paul Broca studied eight patients with language problems. He examined their brains after death and found that they had damage to a specific area of their left hemispheres. This area has been named ‘Broca’s area’; it is associated with speech production and found in the posterior portion of the frontal lobe. Carl Wernicke, a German neurologist, discovered another area of the brain that was involved in understanding language. This area, named ‘Wernicke’s area’, is in the posterior portion of the left temporal lobe. His patients could speak but were unable to understand language.

Assumption 2: localisation of brain function EXTRA: Remember the case of Phineas Gage? What happened to him? How does this link to brain localisation?

Some interesting brain facts!

Key Terms “You Say We Pay” The Biological Approach Neuron Oxytocin Lobe Receptor Seratonin Adaptive Synapse Wenicke’s Area Neurotransmitter Dopamine Broca’s Area Dendrite Natural Selection

Explaining relationships Without looking at the book, how could the biological approach apply to human relationships? Romantic relationships Sibling relationships Parent/child relationships Pet/Owner relationships Read the box on page 11. What do you think? We will come back to this question again once we have done all 5 approaches.

Explaining relationships Evolutionary theory Relationships form with individuals who possess certain traits – the traits that enhance reproduction are naturally selected. Males and females have different selective pressures. Males look for: Fertility (young) Health (smooth skin, red lips, narrow waist) Females look for: Fertility and health Resources (food and shelter) Parental investment theory (Trivers, 1972) suggests that as female investment is so high they must be choosier when it comes to a partner. This explains why younger women often go for an older male.

Explaining relationships Neurotransmitters Dopamine is pleasure seeking and reward-driven behaviour. So finding a relationship will give a hit of this. Oxytocin is linked with human bonding, trust and loyalty. High levels of oxytocin are linked to romantic attachment – a lack of physical contact will reduce oxytocin, leading to feelings of longing. Kin selection – traits that enhance the chance of survival of those with similar genes. Natural incentive to help our siblings survive. This is through time, energy and resources to promote health. Explaining relationships (sibling)

Application Task

Balloon Label the four lobes of the brain. frontal lobes deal with thinking and creativity. parietal lobes receives sensory information such as temperature, touch and pain. temporal lobes are responsible for memory processing, as well as processing auditory information. occipital lobe deals with vision and receives information directly from the eyes. Label Wernicke’s and Broca’s areas. Find out which areas of the brain are affected by Addiction Depression Criminal behaviour Love Challenge: Use the 3D brain app to find another area of the brain and it’s responsibility.

Answers Addiction = limbic system Depression = amygdala Criminal behaviour = amygdala Love = striatum

Homework Create a flashcard on the assumptions of the biological approach. Use the SEE format: State the assumption Explain and elaborate, and give an Example in Psychology You’ll have a quick test next lesson!