biological approach

• Biological approach


  Assumes everything psychological was first biological and so to understand human behaviour we have to look at the biological structures within them
• Genetics


  • Typically each individual is born with 23 pairs of chromosomes which they get from their biological parents, these are our genotypes
  • These form our DNA, which carries instructions for our characteristics
• Genetics influence behaviour


  e.g. intelligence is inherited in the same way that height is
• Twin studies


  1. Used to investigate genetic influence

  2. Concordance rates are analysed, to show the extent to which twins share the same characteristic/s
• If a characteristic is genetic, it would be expected that all MZ twins would share the characteristics as they share 100% of their genetics
• McGuffin et al. (1996)


  • Found there was a 46% chance if one twin had depression, that the other twin would also have it. This suggests there is a genetic component to illnesses such as depression
• Biological psychologists recognise the importance of biological structures and neurochemistry in the body and the role it plays in behaviour
• Endocrine system


  • A chemical messaging system that operates throughout the body
  • Releases hormones into the bloodstream
• Pituitary gland


  • Controls the release of hormones from other glands
  • Known as the master gland
• Adrenal gland


  • Releases adrenaline/ noradrenaline as part of the fight/ flight response
• Reflex arc


  A collection of cells that transmit information
• Components of reflex arc

  • Sensory neurons
  • Relay neurons
  • Motor neurons
• Sensory neurons


  Send information from the senses e.g. touching a hot radiator, to the brain e.g. pulling hand off the radiator
• Relay neurons


  • Connect with other neurons
  • Analyse sensations
  • Decide which response to make
  • Act between sensory and motor neurons
• Motor neurons


  Send messages from axons in neurons to the muscles
• Synapse


  • Found at the end of the cell
  • Synaptic transmission allows neurons to communicate by passing chemical signals/messages between them
• Types of neurotransmitters


  • Excitatory
  • Inhibitory
• Excitatory neurotransmitters


  • Increase the likelihood of a new action forming in the postsynaptic cell
  • When the receptors are detected, the electrical charge inside becomes more positive and likely to fire, known as depolarisation
• Inhibitory neurotransmitters


  • Decrease the likelihood of a new action forming the postsynaptic cell
  • When the receptors are detected, the electrical charge inside becomes more negative and less likely to fire, known as Hyperpolarisation
• Synapse transmission


  1. Action potential travels down the axon of the presynaptic neuron

  2. Vesicles containing neurotransmitters merge with the cell membrane and release the neurotransmitter into the synaptic cleft

  3. Receptors on the postsynaptic neuron's dendrite membrane detect the neurotransmitters, changing the chemistry of the postsynaptic neuron

  4. If the change inside the postsynaptic neuron passes a threshold, a new action potential is triggered and the message is passed on

  5. The neurotransmitters detach from the receptors and return to the presynaptic cell via transport proteins, (known as reuptake)
• Nervous system


  The collection of nerve cells that sends electrical messages around the body
• Components of the nervous system

  • Central Nervous System
  • Peripheral Nervous System
• Central Nervous System


  • Contains the brain and spinal chord
  • Receives information, processes it and makes decisions
• Peripheral Nervous System


  • Information across the body to the brain
  • Sends decisions from the brain to the body
• Brain regions


  • Brain Stem
  • Temporal Lobe
  • Frontal Lobe
  • Cerebellum
  • Cerebral Cortex
  • Occipital Lobe
  • Parietal Lobe
• Brain Stem


  • Connects the brain to the spine and rest of the body
  • Regulates basic functions such as breathing, heart rate, eating and sleeping
• Temporal Lobe


  • Controls hearing/ auditory perception
  • Controls speech comprehension, processing sounds and noise to speech
• Frontal Lobe


  • Predicts future consequences
  • Linked to executive control e.g. not acting on impulses, thinking, reflecting
• Cerebellum


  • Receives information from the spinal cord, sensory systems and other parts of the brain
  • Regulates balance and motor movements
• Cerebral Cortex


  • Largest area of the brain
  • Controls; cognition, perception, consciousness, memory, attention, awareness, thought and language
• Occipital Lobe


  Processes visual stimuli, such as colour, orientation and shape
• Parietal Lobe


  Regulates sensory information from across the body
• Genotype


  • Genetic makeup, the particular set of genes a person possess
  • Everyone has a unique genotype (apart from MZ who share 100% of their DNA)
  • On average, a individual has around 100,000 genes
  • One genotype determines certain characteristics such as eye and hair colour
• Phenotype


  • The expression of the genes
  • The characteristics of an individual determined by both their genes and how they are expressed in their environment
  • An individual's genotype will determine how tall they could potentially grow, however, environmental factors, such as nutrition will determine whether or not they reach their maximum height
  • An individual may be predisposed to a certain behaviour e.g. criminality but this behaviour may only be expressed if specific environmental factors are in place e.g. lack of money; mixing with the 'wrong' crowd
• A genetic basis to behaviour is part of the Biological Approach, rooting behaviours in physical/physiological contexts, including evolutionary psychology
• Both physical and internal (e.g. mental) characteristics are inherited. Traits present in current behaviour may be present as evolutionary processes have selected the most adaptable and useful genes for continued survival
• Some traits are innate rather than being the product of environmental influences e.g. physical characteristics such as eye colour, as well as 'invisible' traits e.g. having an innate predisposition for musical ability or sporting prowess
• Evolution & behaviour


  • Evolutionary psychology is part of the biological approach to explaining behaviour (based on Darwin's theory) which explains how and why behaviours e.g. aggression, memory, language, mate selection are the products of natural selection
  • Natural selection is the process whereby behaviours and traits which are useful for survival and reproduction are retained – and those which are not eventually die out
  • Adaptive behaviours are those which increase the chances of survival and reproductive success which is why they are passed down through the generations i.e. how we behave now is the product of causes rooted in the past
  • Genes are the mechanisms which drive evolution: any genetically determined behaviour which increases a specie's chance of survival will be passed down to future generations
• Biological psychologists believe characteristics such as intelligence is adaptive as it enhances human survival - for our ancestors intelligence manifested as knowing where to find the best food source, understanding weather patterns, fashioning tools, creating transport, negotiating with other tribes etc. and intelligence today equals further education/training/an entrepeneurial drive, a good job which should ensure security and abundance of resources, the ability to network and make useful social/professional contacts etc.
• Other human behaviours believed to be adaptive include memory and attachment: Memory may be adaptive as it has evolved to enable our survival e.g. memory for faces ('friend or foe?') and Attachment to a primary caregiver is adaptive as it increases an infant's chances of surviving