The Biological Approach

• What are the fundamental underlying assumptions of the biological approach?

  • All human behaviour/psychology stems from our biology
  • All mental states correspond with brain states
  • Emotions stem from biochemistry
  • Biochemistry affected by biological structures, processes + genes
• What role does evolution play in psychology?

  • Darwin:
  • Species change due to natural + sexual selection
  • Genes undergo random mutations + they are kept if they fit within evolutionary pressures of environment
  • This trait outperforms its competition + produces more offspring
  • Adaptive genes increase in gene pool = become increasingly common in population
• What does evolutionary psychology build upon?

  • Idea that some traits + behaviours are now innate in humans because they are hard-wired into our DNA/genes
  • Human evolution 30,000-3,000,000 years ago can still be used to explain human behaviour today
  • People are genetically predisposed to certain behaviours
• Evolution + behaviour:

  • Humans evolved on EEA (Environment of Evolutionary Adaptiveness) in African Savannah -> 30,000-3,000,000 years ago
  • Behaviours are responses to ultimate, not proximate causes
  • Evolutionary Psychology approach
• What is an ultimate cause for behaviour?

  An ancient threat to survival, e.g. saber-toothed tigers about to kill prehistoric human
• What is a proximate cause for behaviour?

  Something immediate + close-by, e.g. an alarm going off in the morning
• Key assumption:

  • Adaptive behavioural traits = passed on/inherited -> some behaviours are universal
• Example of adaptive behavioural trait:

  • Attachment (Bowlby 1969)
  • Attachment = adaptive because it secures:
  • Caregiving + protection
  • Ability to form relationships
• Key assumption:

  • If humans have inherited biological structures, behaviours and/or predispositions to behaviours from ancestors, this MUST be embedded in our genetic code
• Key assumption:

  • Interactions of our genes underpin our behaviour
  • Extent of impact = focus on nature-nurture debate
  • Genes = sections of DNA found in chromosomes
  • Humans typically have 46 chromosomes (23 from each parent) + approx. 100,000 interacting genes
  • Genes contain 'instructions' to the body to produce specific molecules (usually protein)
  • Protein controls how body grows + works = responsible for many of our characteristics
  • Genetic code = person's genotype
• Key terms:

  • Heredity = passing of characteristics from parents to offspring
  • Heritability = amount of (observable) variation in a trait within a population that can be attributed to genetic differences (e.g. intelligence)
• What is a genotype?


  • Genetic code in person's DNA (genes)
  • Combination of alleles
  • Guides development of individual
  • Dictates characteristics with 100% heritability
• What is a phenotype?


  • Genetic code in DNA AND interaction with environment (from conception)
  • Physical expression of genetic potential, e.g. eye colour
  • For behaviours with variable heritability = expression of gene depends on impact of individual's environment, e.g. height
• Influence of genes:

  • Because humans have instructions for our development embedded in our genetic code it means that our genes impact on the biological structures + neurochemistry that also influences our behaviour!!
• Key assumption:

  • Biological structures impact on behaviour
  • Key biological structures = the nervous system + the endocrine system
• Influence of biological structures on behaviour

  • The endocrine system
  • Glands
  • 'Master gland' = pituitary gland
  • Other glands: testes, adrenal gland, saliva glands, ovaries, etc
• Glands

  • Produce hormones
  • Directly into bloodstream
  • Stimulate 'receptors' on target cells
  • Causes physiological reaction
• Key assumption:

  • Hormones change physiological activity + therefore behaviour, e.g. testosterone
• What is included in the central nervous system (CNS)?

  • Brain (motor neurones)
  • Spinal cord (relay neurones)
• What is included in the peripheral nervous system (PNS)?

  • Sensory receptors (sensory neurones)
• Which glands are in the endocrine system?

  • Hypothalamus (Fight or Flight)
  • Pituitary gland ('master gland')
  • Pineal gland (melatonin)
  • Thyroid gland (metabolism + energy)
  • Adrenal gland (adrenaline -> short-term boost in energy + important in ForF)
  • Pancreas (insulin, glucagon + pancreatic polypeptide)
  • Ovaries (oestrogen, progesterone + testosterone)
  • Testes (testosterone)
• What are the different parts within the brain?

  • Frontal lobe (speech, thought + learning)
  • Parietal lobe (sensory info, e.g. touch, temp + pain)
  • Occipital lobe (visual info)
  • Temporal lobe (hearing + memory)
  • Brain stem (digestion, heartbeat)
  • Cerebellum (coordinates info coming from spine + regulates movement)
• What are the different parts involved in a synapse?

  Action potential in axon terminal of presynaptic neurone -> vesicles -> neurotransmitters -> transporters -> synaptic cleft -> postsynaptic receptors -> action potential continues from postsynaptic neurone
• How do the CNS and PNS communicate?

  • Transmit messages via electrical signals along neurones
• The central nervous system

  • Brain
  • Different parts
  • Cerebrum = approx. 85% of brain
  • Responsible for 'higher order' functions (reasoning, language, memory)
  • Brain has 2 halves = hemispheres (left +right)
  • Hemispheres have 4 parts = lobes
  • Transmit messages via neurones
  • Spinal cord = also transmits messages via neurones
• Key assumption:

  • Neuroanatomy changes physiological activity and therefore behaviour
  • e.g. Broca (1861) -> patient Tan
  • e.g. lowered serotonin levels + heightened dopamine levels = linked to OCD symptoms
• What is meant by the 'neurochemistry of the nervous system'?

  • Neurotransmitters
  • Chemical messengers
  • Communicate meaning of nerve impulse
  • Via synaptic gap
  • = synaptic transmission
• What is the process of synaptic transmission?

  • Presynaptic neurone releases neurotransmitters
  • NTs bind with receptors on postsynaptic neurone
  • Excitatory NTs = positively charged, e.g. dopamine
  • Inhibitory NTs = negatively charged, e.g. serotonin
  • Summation = whether the action potential fires or not from the postsynaptic neurone
  • Impossible if more inhibitory NTs than excitatory NTs!
• Biological approach as investigated through animals

  • Bard + Mountcastle (1937)
  • Separated cortex from limbic system + damaging hypothalamus in cats
  • = tendency towards intense aggression!!
  • Problem of extrapolation -> human brains = different from animal brains -> different cognitive capacities
• Biological approach as investigated through correlational studies

  • e.g. family studies into genes
  • Nestadt et al. (2000)
  • 1st degree relatives of OCD havers = 11.7% possibility of development
  • General population of 2.7% possibility of development
  • However -> extra 9% probability could be due to living with those 1st degree relatives with OCD BECAUSE of their OCD -> OCD is conditioned or Freudian?
• Biological approach as investigated through correlational studies

  • e.g. twin studies into genes
  • MZ (identical) twins = 100% shared DNA
  • DZ (fraternal) twins = 50% shared DNA
  • DZ twins = environmental control for shared environment growing up
  • Miguel et al. (1977) -> studies look for concordance rates
  • BUT, no twin studies have ever shown 100% concordance for non-physical characteristics = behaviour likely influenced by environmental factors as well as biology
• Biological approach as investigated through correlational studies

  • e.g. studies into impact of endocrine system
  • Dolan et al. (2001) -> impact of testosterone on aggression = positive correlation (T increases + aggression increases)
  • e.g. brain scanning techniques
  • fMRI (functional magnetic resonance imagery)
  • EEG (electroencephalogram)
  • ERPs (event-related potentials)
  • Post-mortem examinations
• Biological approach as investigated through quasi-experiments

  • e.g. studies into neurochemistry
  • Virkkunen et al. (1994)
  • Metabolite 5-HIAA in cerebrospinal fluid = much lower in violent impulsive offenders than violent non-impulsive offenders
  • 5-HIAA = serotonin waste product = lowered serotonin (inhibitory NT) in violent impulsive offenders?
• Key assumption:

  • Biological factors that impact behaviour can be studied through:
  • Animal studies + quasi-experiments (cause + effect)
  • Correlational studies (correlations between biology + behaviour)
  • ...in which variables can be objectively operationalised
• Biological approach A&E point 1: this approach is too deterministic

  • Suggests that there is no free will + that certain genes (Abdemalek Bayout's 2009 MOAO gene) = behaviour 100% going to happen
  • Murderers + rapists let out of prison because they were biologically predisposed to commit crimes + it was therefore not their fault?
  • Convicts let back into society = more innocent people harmed?
• Biological approach A&E point 2: beneficial real-life applications

  • March et al. (2007) -> antidepressants = 81% effective
  • Soomro et al. (2008) -> placebos not as effective as real meds for OCD
  • People with depression + OCD more easily treated because of biological approach's link between behaviour + biology = improved quality of life
• Biological approach A&E point 3: biological approach can lead to eugenics

  • Genes = certain characteristics, so 'undesirable' characteristics can be eradicated through forced sterilisation of minority groups
  • Psychological research often focused on WEIRD samples + is therefore ethnocentric -> biases in research = negative implications, e.g. APA's research = forced sterilisation of many black + hispanic people in 1910s-20s
  • APA had to apologise to POC in 2021