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
• Genotypes


  The particular set of genes a person possesses
• DNA


  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 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
• Endocrine system


  A chemical messaging system that operates throughout the body
• 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
• Sensory neurons


  • Send information from the senses to the brain
• 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, allows neurons to communicate by passing chemical signals/messages between them
• Neurotransmitters


  Chemical messengers released at the synapse
• Excitatory neurotransmitters


  • Increase the likelihood of a new action forming in the postsynaptic cell
• Inhibitory neurotransmitters


  • Decrease the likelihood of a new action forming in the postsynaptic cell
• Synapse transmission


  1. Action potential travels down the axon

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

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

  4. If change passes threshold, new action potential is triggered

  5. Neurotransmitters detach from receptors and return to presynaptic cell via transport proteins (reuptake)
• Central Nervous System


  Contains the brain and spinal cord, receives information, processes it and makes decisions
• Peripheral Nervous System


  Sends information across the body to the brain, sends decisions from the brain to the body
• Brain Stem


  • Connects the brain to the spine and regulates basic functions such as breathing, heart rate, eating and sleeping
• Temporal Lobe


  • Controls hearing/auditory perception, 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 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 possesses
• Phenotype

  The expression of the genes, the characteristics of an individual determined by both their genes and how they are expressed in their environment
• Evolution


  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


  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


  Those which increase the chances of survival and reproductive success which is why they are passed down through the generations
• 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 are adaptive as it enhances human survival and increases chances of security and resources
• Other human behaviours believed to be adaptive include memory and attachment
• Research investigating evolution & behaviour

  • Clarke & Hatfield (1989) - female choosiness when dating/having sex with a stranger
  • Curtis et al. (2004) - higher levels of disgust for disease-salient images