The Biological Approach

• basic assumptions of the biological approach?

  1. human behaviour is influenced by genetic make-up which evolve through evolutionary adaptation.
  2. CNS (central nervous system: brain, spinal cord) is essential in thought and behaviour.
  3. chemical processes in the brain (neurotransmitter) and body (hormones) influence our behaviour.
  4. humans and animals have the same physiology and therefore can be studied in the same way.
• what are the research methods used by the biological approach?

  • brain scanning techniques- fMRI, MRI, CAT scans, PET scans.
  • EEG
  • post mortem studies
  • case studies of specific people
  • twin studies/adoption studies
  • selective breeding
  • animal studies
• what are the 3 main areas within the biological approach?

  • influence of genes on our thought and behaviour and how these have evolved.
  • role of biological structures on our behaviour such as the CNS.
  • chemistry of our bodies including the neurotransmitters and hormones.
• the nature/nurture debate?

  • traditionally, biological psychologists believed behaviour was completely biological.
  • now, however, biological psychologists agree that there is an interaction between nature and nurture. our nature can influence nurture.
• the study of genes:

  • psychologists want to know how our genes interact w/the environment.
  • they look at both our:

  1. genotype = our genetic makeup made up of chromosomes, e.g. eye colour
  2. phenotype = the physical/behavioural/psychological traits that can be measured or observed, e.g. IQ, height, etc.
• formula for phenotype:

  genotype + environment = phenotype
• chromosomes:

  • organisms inherit alleles = pieces of info stored in our genes from their parents (inherited via the sex cells gametes).
  • alleles that are beneficial have given organisms an advantage in the past; behavioural or physical advantage 'survival of the fittest'.
  • humans have 46 chromosomes- 23 pairs.
• sex cells:

  • testies and ovaries contain sex cells, i.e. sperm and eggs.
  • in humans, meiosis occurs, dividing chromosomes in 1/2, so that each sex cell has 1/2 the amount of chromosomes compared to 'normal'.
• eye colour genotype:

  • a person might have a genotype that includes genes for both brown eyes and blue eyes (heterozygous).
  • however, their phenotype might show brown eyes because the gene for brown eyes is dominant over the gene for blue eyes.
  • illustrates how the genotype (genetic potential) can result in a specific phenotype, influenced by dominant and recessive gene interactions.
• what is used to study the biological basis of behaviour?

  • both psychology and genetics.
  • many physical characteristics are inherited.
  • unsure about behaviours such as:

  1. sexual orientation
  2. intelligence
  3. personality
• twin studies:

  • carried out by comparing the extent to which monozygotic twins (100% genetically similar) both have specific disorders or behaviours compared to dizygotic twins (who share approx. 50% of genetics).
  • look at concordance.
• adoption studies:

  • don't usually involve twins. these days, twins are almost always put up for adoption together.
  • usually measured using a correlational technique: looking for correlation between behaviour of children and their parents.
  • look at concordance.
• family studies:

  • studies of families to measure the xtent to which traits such as mental illness runs in families.
  • offspring are compared to their parents.
  • if a trait is shared by parents and offspring it suggests that it may be biological and therefore inherited.
• selective breeding:

  • when a psychologist selects a male and a female of an animal w/a specific trait. they're then put together to breed.
  • if trait is passed onto subsequent generations, it suggests that the behaviour is genetic.
• the theory of evolution: key ideas

  • different species have all evolved from simple life forms which lived on earth 3 billion years ago.
  • evolution occurs through natural selection.
• natural selection:

  • there are variations in species.
  • too many young are produced so there is competition for food, water, shelter, etc.
  • animals survive because they have traits that give them an advantage in getting food, water, etc.
  • behaviour is adpated to suit the current environment and aid their survivial- 'survival of the fittest'.
  • these 'fit' animals will go on to have offspring and pass on their 'adoptive' traits onto their offspring.
• biological structures and neurochemistry:

  • the human body is a collection of biological systems which intergrate to help us live.
  • there are key structures within those systems which are particularly useful in terms of explaining the behaviour and psychology of the individual.
• the nervous system:

  • divided into 2 pairs: the central nervous system (CNS) and the peripheral nervous system (PNS).
• central nervous system:

  • consists of the brain and spinal cord.
  • pivotal in transferring messages to and from the environment.
  • act as the centre from which all the physiology of the individual is controlled.
  • breathing, eating, the heartbeat and the senses are all co-ordinated from the CNS.
  • biopsychologists look to the brain for behaviour as most actions & reactions are generated from the CNS.
• peripheral nervous system:

  • sends & receives signals from the CNS.
  • responsible for the working of the limbs+torso, which collect info from the environment in terms of temp, pain and threat.
• autonomic system:

  important for survival of the individual, affects reaction to threat, homeostasis.
• somatic system:

  • comprises the muscles attached to the skeleton and is therefore very important in movement.
  • also receives info from the skin, e.g. environment temp.
• the neuron:

  • a nerve cell that transfers info between the nervous systems.
  • billions within the human body.
  • vary depending on job.
• the endocrine system:

  • not a part of the nervous system.
  • important in terms of biochemistry of the body.
  • main job is to maintain levels of hormones in the blood and other bodily fluids.
  • done by using glands in the body.
  • pituitary gland instructs the other glands to secrete hormones when necessary.
  • biopsychologists argue that the level of a hormone in the system can affect the behaviour of an individual.
• wha is neurochemistry?

  the biochemistry of the CNS consisting of the transmission of neurotransmitters.
• what are hormones?

  chemicals which travel through the blood .
• what are neurotransmitters?

  chemicals which travel via the cerbral fluid in the brain.
• what do biopsychologists think?

  that hormones and neurotransmitters affect behaviour, e.g. high levels of dopamine is linked to SZ.
• quick evaluation of the approach:

  • strength- adopts scientific methods for investigation using largely objective measures, e.g. brain scanning and biochemical levels.
  • strength- biopsychology research can result in practical applications, e.g. drug development and helping people w/psychological problems.
  • weakness- some biological explanations are too simplistic and reductionist as they can often fail to acknowledge the role of the environment in behaviour.
• example study of twin studies?

  wilson (1978, 1983) found:

  • by 18 months old MZ twins had higher concordance than DZ twins for intelligence.
  • follow up study 13 years later supported this.
• evaluation of twin studies:

  • strength- valid way of studying nature/nurture- naturally occuring group.
  • strength- relatively inexpensive to carry out.
  • weakness- small sample studies, difficult to find twins that fit the criteria.
  • weakness- difficult to determine the influence of shared environment (nurture) and shared genetics (nature)
• example study of adoption studies?

  plomin et al. (1997) found:

  • some children whose biological mothers DID have SZ, also had the disorder but no children whose biological mothers DIDN'T have SZ suffered from this disorder.
• evaluation of adoption studies:

  • strength- easier to separate enivronment vs biology.
  • strength- easier to carry out.
  • weakness- small sample sizes.
  • weakness- ethical issues, contacting biological parents.
  • weakness- must be adopted from an early age to minimise effects of shared environment.
  • weakness- children often placed in families similar to biological families.
• example study of selective breeding?

  tyron (1940)- complex maze which rats had to race around. rats times and no. of mistakes recorded.

  • bright rats bred w/other bright rats, dull rats bred w/other dull rats.
  • maze bright rats learnt to run the race quicker and w/fewer errors over generations.
  • supports idea that there's a genetic basis for intelligence.
• evaluation of selective breeding:

  • strength- quick way of measuring the inheritability of traits that it would take too long to study in humans.
  • weakness- ethical issues, can lead to complications such as health problems and increased susceptibility of disease due to inbreeding.
  • weakness- difficult to generalise to humans.
• example of a family study?

  ginoulakis, khrishnan and thavundayil (1996) found:

  • sons of alcoholic fathers more likely to be alcoholics.
• evaluation of family studies:

  • strength- easy to carry out, easy to analyse patterns of behaviours in generations.
  • weakness- hard to decipher which is more influential, shared environment or shared biology.
• genes:

  • according to darwin, evolution occurs in human organisms, this is concerned w/how genetic make-up can change between generations which help to survive in their environment.
  • for this to happen, genes need to be inherited from our parents.
  • any small mutation within those genes can cause differences between generations of offspring.
• chromosomes:

  • organisms inherit alleles from their parents; these are pieces of info stored in our genes. these are inherited via the sex cells known as gametes.
  • alleles that are beneficial have given organisms an advantage in the past, this could be a behavioural or physical advantage. this links to darwin's idea of the 'survival of the fittest' in that something that is an evolutionary advantage will be passed on to the next gen.
  • in the body, humans have 46 chromosomes, or 23 pairs of chromosomes.
• how are sex cells made?

  • testies and ovaries contain sex cells, i.e. sperm and eggs. in humans a process called meiosis occurs, which divides the chromosomes in half, so that each sex cell has half the amount of chromosomes compared to 'normal'.
  • when the two sex cells come together, you have two sets of 23 chromosomes = 46 chromosomes of a normal human being.
  • after this has happened, mitosis occurs. this is when cells (chromosomes) are copied continuously to make up the cells in the body.
  • every sperm and egg cell is different and contains diff chromosomes. it depends on how the cells are split during meiosis.
  • this leads to a potential for diff behaviour, characteristics or traits among biological relations, e.g. siblings.