Biological approach

• The biological approach suggests biological structures and processes in the body can explain human behaviour e.g. genes and the nervous system

  • Understanding the brain structure helps us understand thoughts & behaviour
  • All thoughts, feeling & behaviour have a physical basis, they are a result of something physical in the body
• Genes influencing behaviour

  Genes are inherited from parents to children

  • They carry information that codes for physical features (e.g. eye colour) and psychological features (e.g.personality)
  • Genes interact with each other and the environment, which changes how the characteristic is expressed. e.g. there's a genetic link for mental illness but the illness is also influenced by a person's life experiences & their environment
• Genotype


  Genetic code written in the DNA of an individual's cells. Inherited genetic material passed from generation from generation.
• Phenotype

  Physical/observable appearance of an individual due to genotypes and the environment
• Every individual has a unique combination of genes that determines their physical characteristics and susceptibility to disease, we all differ.
• Heritability

  The amount of variability within a population that can be attributed to genetic differences between individuals within that population

  • the more a trait is influenced by genetics, the greater the heritability (more similar = greater heritability)
• Mono zygotic twins 


  Identical twins, develop from one egg, genes are very similar, sometimes 100% the same
• dizygotic twins

  Fraternal twins, form from 2 separate eggs. They share around 50% of the same genetic material and can be different genders
• Adoption studies look at the impacts of the environment on behaviour. Twins may have the same phenotype but may act differently based on their environment and how they were raised
• Charles Darwin proposed a theory called natural selection. If an animal has a characteristic that helps it survive it is more likely to live and reproduce, meaning that the characteristic is passed on to the next generation through genes

  If you have a trait that helps you survive it means you have an evolutionary advantage as you've adapted to the environment.
• If you have a trait that makes you more attractive as a mate, you will increase your chances of passing your genes onto the next generation. This is called sexual selection
• Evolution can explain how physical characteristics and behaviour can be passed on through generations
• natural selection

  The process by which inherited characteristics that enhance and individual's reproductive success (or fitness) are passed onto the next generation, and so overtime become widespread in the population
• biological structures are organs (such as the brain) and systems (such as the nervous system) that influence human behaviour.
• The nervous system has several connected systems

  • The central nervous system (CNS) compromises the brain and spinal cord
  • The peripheral nervous system (PNS) compromises the somatic and autonomic nervous system.
  • Messages are carried around the body using the nervous system and individual nerve cells, known as neurons
• The largest part of the brain is the cerebrum (85% of total mass)

  • the outer surface off the cerebrum is the the cerebral cortex which contains higher order functions, such as language.
  • The cerebrum is divided into 2 halves (hemispheres) with each hemisphere divided into 4 different parts called lobes
• The frontal lobe is responsible for functions such as speech, thought and learning

  
• The parietal lobe is responsible for spatial awareness, language comprehension, and motor planning

  
• The occipital lobe is responsible for visual processing and is located at the back of the brain.

  
• The temporal lobe is responsible for hearing, memory, and language.

  
• Genes code for proteins that influence neurochemistry
• The process of synaptic transmission:

  • Signals cross between neurons at the synapse
  • This is called synaptic transmission; it refers to how the nervous system transmits information across a "synaptic cleft" (the physical gap between nerve cells) from one neuron to another. This is accomplished by the body's production of chemicals called neurotransmitters

  
• Hormones:

  • Chemicals produced by endocrine glands e.g pituitary gland
  • Responding to a brain's signal, hormones are secreted directly into the bloodstream by the endocrine glands where they travel to target cells & exert their influence
  • This presence of hormones in the cells causes a physiological reaction, altering its activity
• Neurotransmitters are chemicals that diffuse across the synapse to the next neuron

  • they carry signals across the synaptic cleft to the receptor site
• Neurotransmitters can be excitatory or inhibitory in their action

  • serotonin is an inhibitory neurotransmitter, resulting in the neuron becoming negatively charged and less likely to fire
  • Adrenaline is a neurotransmitter that causes excitation of the neuron, resulting in a positive charge and making it more likely to fire.
• Neurotransmitters effect the behaviour in many ways, for example; having a low level of the neurotransmitter serotonin is linked to higher levels of aggression
• Seratonin is associated with mood regulation - when there is not enough serotonin we may experience depression
• A03, biological approach, the importance of the scientific method

  Biological approach often uses the experimental and scientific method to investigate

  • studies take place in highly controlled environments and so are easily replicable in the same environment, increasing validity of research
  • Sophisticated imagery and recording techniques increase the precision and objectivity of experimental research

  These techniques increase the scientific validity of the biological approach
• AO3, biological approach

  Applications of the biological approach

  It provides clear predictions on how biological structures influence behaviour, this is significantly useful in the real world

  • research into the role of neurochemical imbalance in depression has led to developing effective drug treatments, helping to treat patients with mental illnesses

  This shows the importance of research into the biological approach to understand behaviour
• AO3, Biological approach

  Biological approach is reductionist


  Criticised for its belief that complex behaviour can be broken down into genes, neurochemicals and hormones.

  Mental disorders are explained by genetic or neurochemical imbalances causing these disorders. However, we must consider other factors influencing behaviour e.g. emotion, these cannot be ignored
• AO3 Biological approach

  Problem for evolutionary explanations

  Human behaviour/evolving is not just survival based. e.g. culture can influence behavioural origins

  E.g. In China, there is a cultural preference for sons being born, resulting in sex-selective abortions. Cultural evolution lead to rapid changes. Many behaviours have no reproductive or survival value but are still passed on through generations
• AO3, Biological approach

  Deterministic


  Cannot say behaviour is simply controlled by biological structures. The role of the environment should be considered. For example, the social learning approach demonstrates the importance of the environment on our behaviour.