The Biological Approach

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The Approach

Biological psychology investigated behaviour in both humans and other animals, and it seeks to explain behaviour on the basis of anatomy, physiology and inheritance.

Over the past 10/15 years, this approach has gained importance in psychology, due to the detailed knowledge scientists have of our genetic make-up and advances in research techniques at a molecular level.

A biological perspective is relevant to psychology in three ways:

  • physiology - investigating how the brain, nervous system and hormones operate; how changes in the structure and function of organs and chemicals can affect our behaviour
  • Investigation of heritability - understanding the role genes may have on behaviour
  • Comparative method - different species of animal are studied and compared to humans
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Basic Assumptions

  • Human behaviour is strongly determined by our genes and genetic inheritence (Behaviour has an innate, biological basis)
  • The CNS, especially the brain plays an essential role in thought and behaviour
  • Chemical processes in the brain are responsible for many different aspects of psychological functioning (eg, schizophrenia, depression)
  • Humans and other animals have evolved biologically through Darwinian evolution. This means animals high in the evolutionary tree (eg, monkeys, apes) are similar genetically to humans
  • The brain and mind are the same. Some philosophers and psychologists have argued the brain is physical and the mind mental, yet biological psychologists enforce they are the same
  • Evolution has taken place over millions of years - human genes have evolved to adapt behaviour to the environment. The 'fight or flight' response is common across the animal kingdom and is important to understand how animals react in threatening situations. 
  • Human characteristics, eg, intelligence, are due to our genetic makeup
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Methods of Investigation

Usually involves highly scientific and technological approaches to research. The functions of different structures in the brain are investigated using techniques such as EEGs or MRIs. Other research methods include:

1) Lab experiments - on humans and animals. Using animals to investigate brain function (eg damaging specific areas of a rat's brain to see role in behaviour). Ethical guidelines strongly determine what can and cannot be done

2) Observation of Behaviour under strict lab conditions - eg, the strange situation (Ainsworth and Bell, 1970) and Sleep experiments

3) Studies of identical and non-identical twins - brought up together or reared apart to help determine the contribution of genes to psychological characteristics

4) Detailed case studies of people (eg, those who have brain damage to understand what roles specific areas of the brain have)

5) Selective breeding in animals (such as rats) to determine which behaviours and characteristics may have a genetic basis

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Biological Structures

  • Neurons: specialised nerve cell which communicates with other neurons in the central/peripheral nervous system or with muscles or organs in the body (eg, eyes or heart). 
  • The Central Nervous System - Brain and spinal cord
  • The Peripheral Nervous System - the somatic system, controls skeletal muscles and recieves info from sensory receptors. The autonomic nervous system controls essential, life maintaining processes, such as breathing, digestion etc. The Autonmic system is made up of the sympathetic and parasympathetic nervous systems.
  • The Endocrine system - secretes hormones into the body through different endocrine glands located in different parts of the body. 
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Role of the Central Nervous System

                                   Nervous     System

                        V                                           V

  Central Nervous System                        Peripheral Nervous System

      V                         V                         V                                     V

Spinal cord             Brain        Autonomic Nervous System          Somatic Nervous System

                                                  V                          V

                                       Sympathetic                Parasympathetic



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The CNS: Cerebral Cortex

Most highly developed part of the brain in humans compared to other animals

Associated with higher level functioning -inc's conscious awareness, personality, problem-solving and creative thinking

As you go up the evolutionary tree, the amount of cortex incereases in comparison to the total size of the brain

Divided into four areas:

  • Occipital lobe - vision - visual cortex
  • Temporal love - hearing - auditory cortex
  • Parietal lobe - sensations from the skin and muscles
  • Frontal lobe - higher thought processes (eg, abstract thinking and reasoning)
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The CNS: Limbic System

Deep in the brain

Involved in emotions, motivation, learning and memory

Also identified as being involved in eating and sexual behaviour

Fundemental to what we think, feel and do

Made up of three structures:

  • The septal area - important for motivation and experience of pleasure
  • Amygdala - Involved in emotions, especially attachment of emotional importance to events. Makes us fearful or afraid and helps us recognise is someone is scared.
  • Hippocampus - involved in memory, particularly recent ones. Damage to the Hippocampus means recent memories are lost but older ones remain.
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Role of the Autonomic nervous system

Responsible for sending information to, and recieveing information from organs responsible for vital bodiliy function (eg, digestion)

Made up of two parts:

  • Sympathetic: Prepares person to deal with danger. Fight of flight response. Directs blood to heart, so heartrate increases, blood pressure increases, pupils dilate and hairs stand on end.
  • Parasympathetic: Supports normal routine and bodily function. Conserves energy and regulates heartrate, blood sugar etc. When danger passed takes control and brings body back to normal.
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The influence of genes

A distinction needs to be made between genetics and heredity and genotype and phenotype:

  • Genetics is the study of the genetic makeup of organisms and how genes influence physical and behavioural characteristics
  • Heredity is the traits, characteristics and behavioural tendencies inherited from one's parents and, in turn, their ancestors (Carlson and Buskit, 1997)
  • Genotype: their actual genetic makup, represented in the normal 23 pairs of chromosomes. Each person (apart from MZ twins) has a unique genotype
  • Phenotype: the actual expression of the person's genetic makeup. This includes physical apperance, behavioural and psychological characteristics (genes+environment)
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Genetic influence

Within most cells, there is a nucleus - these contain 46 structures called chromosomes. These are made of DNA, and the DNA of each chromosome carries genes. 

Our genes interact with the environment to influence every aspect of bodily structure and function

Research on genetic influence has often been conducted on non-human species such as rats and mice. Psychologists are able to manipulate certain genes in order to measure the effects on behaviour. Genetic mapping, engineering and selective breeding programmes have contributed enormously to our understanding of the genetic basis of behaviour.

Bock and Goode (1996) found that when mice were reared alone, they showed a strong tendency to attack other male mice when first exposed to other animals. These mice were not taught to be agressive, that is from their parents, they just exhibited the behaviour. This research implies a natural/genetic tendency in biological aggression.

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Methods of Investigation (genes)

  • Twin studies - particularly identical twins raised apart
  • Adoption studies - also help determine the extent to which characteristics and behaviours are similar to natural or adopted parents
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Examples of genetics and heredity

Anxiety = thought to have a genetic basis and some thought to have a genetic predisposition (may be triggered by the environment), a high level of neural activity in the amygdala associated with anxiety. May be a contribution of a number of genes.

Obesity = Twin studies show that body weight and the amount of fat in the body has a strong genetic basis

Homosexuality = Evidence put forward to show that homosexuality among males may have a genetic basis. Concordanance rates for MZ twins was 50% compared to 20% for DZ twins. However environmental factors play at least an equally important part.

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Chromosome abnormalities

Down's Syndrome: Extra chromosome, usually from mother's side. Affects around 1 in 700 children

Turner's Syndrome: Female has only 1X chromosome instead of 2. They are usually sterile, other physical anomaliles but mental functioning is fine. Some cognitive defiects.

Huntington's Cholera: Have servere memory impairment, personality change and show uncontrollable body movements. Affects 1 in 10,000, and more common in white Europeans - abnormal gene on chromosome 4. 50% chance of inheriting the disorder if a parent has it.

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The evolution of behaviour

Darwin put forward his theory of evolution and the mechanism to explain how evolution works (natural selection) in his 'The Origin of Species'

Natural Selection: The idea that those animals who survive have particular traits that give them an advantage compared with the others. This behaviour is adapted and suited to the environment - these 'fit' animals will survive and leave more offspring, and therefore the genes will be passed on and the species will survive. These 'adaptive' traits will therefore survive and be passed on and across generations.

Sexual Selection: according to Darwin, the peacock's tail should have become smaller, as it is a disadvantage to the peacock - it would weigh it down when confronted by predators. This has not happened as the tail attracts the pea hen, and so is selected and continues to be passed on. This is sexual selection.

Females are more careful than males when selecting a mate as men can father as many children as they like, whereas women have to give birth.

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Evolutionary Psychology

Darwin also influenced evolutionary psychology. These psychologists (Buss, 1995), try to explain behaviour in terms of how people adapt to a constantly changing environment. They claim that genes account for not only physical characteristics, but also psychological characteristics such as personlity traits and intelligence.

They also claim musical ability result from genes passed down by parents (Plomin and DeFries, 1998)

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Evaluation: Strengths

  • Adopts highly scientific methods of investigation, studies can therefore be replicated
  • It is objective
  • Lots of human behaviour can be explained by this approach
  • Twin and adoption studies have provided ways of estimating the heritablility of a range of psychological characteristics
  • Can conduct experiments on non-human animals that can't be done for ethical reasons (eg, drug research)
  • Provides strong arguments for nature side of nature-nurture debate
  • Has many useful applications (such as drugs for depression/schizophrenia)
  • Understands the role of the brain in higher mental functions, such as memory
  • Approach shows how evolution and genetics influence behaviour and play a role in child development
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Evaluation: Limitations

  • Reductionist explanation - ignores the whole person
  • Ethical issues with research on animals
  • It over-emphasises the importance of biological processes and heritablility at the expense of environmental influences
  • Research can be very expensive to conduct because of the advancement in technology
  • Some areas are therefore overprioritised over others
  • Ignores the influence of the environment on many behaviours
  • Extreme on the nature/nurture
  • Difficulty explaining one of the most distinctive aspects of being human - that of consciousness and self-consciousness (self awareness)
  • The biological approach presents a too simplistic view of human behaviour as it doesn't fully recognise the importance of social factors - culture and society- in influencing human behaviour
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  • Drugs developed to treat severe mental illnesses such as schizophrenia and bipolar
  • Knowledge on the structure and function of the brain provides an understanding of how damage to the brain may affect thought and behaviour
  • Genetic engineering has led to possible treatments for genetic disorders.
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