biological approach

• Key assumptions:

  1. human behaviour is influenced by physical processes
  2. everything psychological is first biological
  3. to study human behaviour we must look at biological structures
  4. patterns of behaviour can be inherited
  5. human genres have evolved over millions of years to adapt behaviour to the environment
• sex hormones

  • hormones are chemical substances secreted by glands throughout the body and carried in the bloodstream
  • the same sex hormones occur in both men and women but in different amounts and affects in the body
  • testosterone is linked to behaviours such as aggression, competitiveness and higher sex drive
• Phineas Gage

  • 3ft long pole was launched into his skull, specifically the pre-frontal cortex, when working on a railroad
  • he did not lose the ability to move or speak and the wound only took 10 weeks to heal
  • however his behaviour changes drastically - he became inconsiderate and rude
  • his skull was examined to learn more about the functions of the brain, specifically whether functions of the brain are localised or holistic
• localisation theory = certain areas of the brain are responsible for certain processes, behaviours and activities

  holistic theory = the brain works as a whole to undertake processes, behaviours and activities
• genotype and phenotype

  • genotype- a person's unique genetic make-up that is coded in their chromosomes and fixed at conception
  • phenotype- an individual's observable traits, such as height, eye colour and blood type. A person's phenotype is determined by both their genomic makeup (genotype) and environmental factors eg sleep, nutrition, exercise, water, learning and experience
• central nervous system

  • the CNS is made up of the brain and spinal cord → it combines information from the entire body and coordinates activity across the whole organism
  • the brain is the centre of all conscious awareness and is responsible for the functions of the body eg speech, 5 senses, movement, awareness, thinking and memory
  • the spinal cord is an extension of the brain. it sends motor commands from the brain to the body, send sensory information from the body to the brain. it is also responsible for reflex actions
• Peripheral nervous system

  • the PNS transmits messages via millions of neurons, to and from the central nervous system. The peripheral nervous system is further divided into the:
  • autonomic nervous system governs vital functions such as breathing, heart rate, digestion, sexual arousal and stress response
  • somatic nervous system controls the muscle movement and receives information from sensory receptors
• Autonomic nervous system


  Governs vital functions such as breathing, heart rate, digestion, sexual arousal and stress response
• Autonomic nervous system


  • Contains two anatomically distinct divisions: sympathetic & parasympathetic nervous system
• Sympathetic nervous system


  Activation leads to the fight or flight response during which the blood pressure and heart rate increases, glycogenolysis ensues, gastrointestinal peristalsis ceases etc.
• Parasympathetic nervous system


  Promotes the 'rest and digest' process during which the heart rate and blood pressure lower, gastrointestinal peristalsis and digestion restarts etc.
• General adaptation syndrome - there are 3 stages that occur in the stress response:

  1. alarm stage- occurs when your body responds to the source of stress. CNS is activated which triggers a cascade of physical reactions (fight or flight)
  2. resistance stage- body working to return itself to its normal stage following the stress reaction (homeostasis) you will slowly calm down and your heart rate and blood pressure will return to normal
  3. exhaustion stage- happens when your body keeps experiencing the first two stages without relief. it becomes chronic stress
• Acute stress = is stress that lasts only for a short period of time. This includes situations such as sitting an exam, starting a new job, giving a speech, or being faced with a work deadline. The body typically bounces back well from acute stress if the stress experienced is effectively managed by the person. sympatho-medullary pathway is activated, triggering fight or flight response
• chronic stress = A consistent sense of feeling pressured and overwhelmed over a long period of time. Symptoms include aches and pains, insomnia or weakness, less socialization, unfocused thinking. The parasympathetic nervous system does not return the body to balance anymore. regulated by the hypothalamic-pituitary-adrenal system
• fight or flight response

  • when someone enters a stressful situation, often triggered by a stressor that causes stress eg an exam, divorce or deadline the amygdala is activated.
  • the amygdala responds to sensory input and connects sensory input with emotions associated with the fight or flight response
  • when in a stressful or dangerous situation, the amygdala sends a distress signal to the hypothalamus, which communicates with the body
• Hypothalamic pituitary adrenal system

  • the stressor activates the HPA
  • the hypothalamus stimulates the pituitary gland
  • the pituitary gland secretes adrenocorticotropic hormone (ACTH)
  • ACTH stimulates adrenal glands to produce the hormone corticosteroid
  • cortisol enables the body to maintain steady supplies of blood sugar
  • steady blood sugar levels help a person cope with a prolonged stressor and help the body return to normal
  • the adrenal cortex releases hormones called cortisol
• NEURONE

  • There are 100 billion neurons in the human nervous system , 80% are located in the brain
  • neurons transmit signals electrically and chemically
  • 3 types of neuron: motor neuron, sensory neuron, motor neuron
• • sensory neurons- carry messages from the peripheral nervous system to the central nervous system, they have long dendrites and short axons
  • relay neuron- connects neurons together, have short dendrites and short axons
  • motor neurons- connect the central nervous system to the muscles and glands, have short dendrites and long axons
• action potential= information is passed down the axon of the neuron as an electrical impulse, once this reaches the end of the axon it needs to be transferred to another tissue via the synaptic gap
• synaptic transmission - messages are transmitted electrically within neurons and chemically between them through the release of neurotransmitters, this has either a excitation or inhibition response
• ENDOCRINE SYSTEM

  • The endocrine system consists of glands which produce chemical substances called hormones.
  • hormones are chemical messengers that are are released and must bind to receptors in order to send their signals, hormones are secreted into the bloodstream and travel throughout the body affecting cells that contain receptors for them. the effect of hormones are widespread.
• homeostasis

  the maintenance of a constant internal environment. homeostasis is a self-regulatory process by which a living organism can maintain internal stability whilst adjusting to the changing external environment. it is a dynamic process that can change internal conditions as required to survive external challenges. examples include the breathing system, respiration, acute stress response and body temperature.
• frontal lobe- associated with higher-order functions including planning, abstract reasoning and logic

  temporal lobe- processes auditory information

  occipital lobe- processes visual information

  parietal lobe- integrates sensory information from the different senses and therefore plays an important role in spatial navigation
• visual cortex- located in the occipital lobe and receives and processes visual information. there are different parts for processing colour, shape and movement

  auditory cortex-located in the temporal lobe and responsible for analysing and processing speech-based information

  motor cortex- located in the frontal lobe and responsible for voluntary movements by sending signals to the muscles

  somatosensory cortex- located in the parietal lobe and receives incoming sensory information from the skin to produce sensations such as pain, pressure and temperature.
• machine vs plastic analogy

  • machine - gives rise to genetic model, health hinges on genetics, use of drugs to support this theory
  • plastic analogy - gave rise to neuroplasticity, health hinges on epigenetics, use of lifestyle to support this theory
• brain plasticity

  • the ability of the brain to make new neural connections and amend existing connections. during childhood, new connections are made and unused ones are deleted
  • it was originally believed to occur during childhood however evidence suggests that this continues throughout adulthood
• MAGUIRE: studied London taxi drivers and found that their brains had a much larger posterior hippocampus than a matched control group. this is possibly because they need to pass a comprehensive test of London’s streets and traffic routes. this part of the brain is involved in spatial navigation skills. the longer the participant had been a taxi driver, the bigger this area of the brain was.
• • neuroplasticity does not consist of a single type of morphological change, but rather includes several different processes that occur throughout life although different types of plasticity dominate during certain periods of ones life and are less prevalent during other periods.
  • neuroplasticity occurs under two conditions:

  1. during normal brain development when the immature brain first begins to process sensory information through to adulthood
  2. as an adaptive mechanism to compensate for lost function and/or to minimise remaining functions in the event of a brain injury
• lateralisation of brain function

  • lateralisation - the idea that each hemisphere of the brain is mainly responsible for certain behaviours, processes and activities
  • right hemisphere controls the left side of the body and the left hemisphere controls the right side of the body
  • split brain patients - people who have had the corpus callosum is cut, separating the two hemispheres, this was used to treat epilepsy
• Sperry & Gazzaniga 1967:

  • aim: examine the extent to which the two hemispheres are specialised for certain functions
  • method: an image/word is projected to the patients left visual field or the right visual field
  • findings: when the information is presented to one hemisphere in a split-brain patient, the information is not transferred because the corpus callosum
  • conclusion: the left hemisphere is dominant in terms of speech and language . secondly the right hemisphere is dominant in terms of visual and motor tasks
• Nature (biological approach)

  • our genetic makeup influences our characteristics, abilities and behaviours. includes genes, hormones, chromosomes and innate characteristics
  • Rene Descartes: human characteristics of knowledge are innate
  • the results of heredity - the genetic transmission of mental and physical characteristics from one generation to another
• brain structures and aggression

  • the limbic system especially the amygdala comprises a collection of brain structures that regulates emotional behaviours including aggression
  • the amygdala has been implicated in assessing and responding to environmental threats. due to learning or habits the amygdala can become more sensitive and consequently more aggressive in situations
  • Gospic (2011) : from FMRI brain scans show high levels of the amygdala reacting quickly and strongly to threatening stimuli
• • testosterone is the male sex hormone, men are considered to be more aggressive because they have higher levels of testosterone than women
  • Daly & Wilson: young men aged 20+ are more aggressive towards each other because they have higher testosterone levels
• • serotonin is a neurotransmitter that is linked to mood regulation and affects disorders such as depression, OCD and schizophrenia if they have too high or too low serotonin levels
  • Denson et al: low serotonin levels in the OFC = disruption of neuron activity = emotional & reduced behavioural self-control = increased impulsive behaviours
• dopamine is a neurotransmitter that helps to regulate mood and control movement. associated with pleasure, reward and motivation. a dopamine boost is a reward that encourages risk-taking and impulsive behaviours
• • cortisol is a hormone referred to as currency of stress . helps regulate metabolism, control blood sugar levels and moderate immune system response. testosterone leads to aggressive behaviour but only when cortisol is low
  • Carre & Mehta: high cortisol blocks testosterones influence on aggression
• • MAOA-L gene is inherited and has been linked to increased aggression and violence. individuals are hypersensitive which can lead to them being more aggressive
  • SRY gene has an indirect influences on aggression by activating testes development in males and triggering testosterone in the womb
• testosterone - high levels of the male sex hormone are associated with development of a masculine-typical in both males and females. testosterone is triggered prenatally of the SRY gene, which starts masculinisation of the embryo. the default developmental pathway is female, which means that without the testosterone the foetus becomes female
• • Baucom et al: high testosterone levels were correlated with a masculine identity and a low testosterone with a feminine identity in biological females
  • knickemeyer & baron-cohen: high testosterone levels were linked to some differences in the brain of men and women, these studies found a bigger amygdala in men than in women
• • congenital adrenal hyperplasia (CAH) is a condition in which genetically female foetus is exposed to abnormally high levels of testosterone. the outcome is the foetus will develop external genitalia resembling a penis
  • CAH children raised as girls often show play behaviour that is more typical of boys.