Explain how principles that define the Biological Level of Analysis may be demonstrated in research.


  • State what you are doing in the essay 
    • This essay will give a brief summary of the principles that define the biological level of analysis, incorporated with supporting research. 
  • Define the biological level of analysis 
    • The biological level of analysis (BLA) states that all cognitions, emotions and behaviours have a physiological basis. 
  • State the principles of the BLA 
    • There are three underlying principles that define the BLA 
      1. Emotions and behaviours are products of the anatomy and physiology of the nervous and endocrine systems 
      2. Animal research may inform our understanding of human behaviour 
      3. Patterns of behaviour can be inherited; behaviour is innate because it is genetically based 
  • Purpose of the Principles 
    • These principles are the main ideas that have driven focused research on specific areas of behaviour and physiology.
    • They also allow us to understanding how behaviour can be caused or influenced by biological factors. 
  • The BLA assumes that behaviour is a result of biological/physiological factors 
    • Links with the principle that there are biological correlates of behaviour. 
  • Bidirectional relationship 
    • Behaviour is not only a result of biological factors alone; other factors like cognitions and the environment interact with one another, resulting in specific behaviours.
    • Cognition can affect biology and biology can affect cognition.
    • The environment can also affect physiological processes and vice versa. 
  • Nature vs. nurture debate 
    • Debate between whether human behaviour is attributed to biological or environmental factors. Psychologists have an interactionist approach and take both into account.
  • Reductionist approach 
    • At the BLA, researchers break down complex human physiology and behaviour into its smallest components to study 
  • Outline Essay
    • Two of the three principles will be outlined and demonstrated with appropriate research studies in the following essay. 


1. Cognitions, emotions and behaviours are products of the anatomy and physiology of our nervous and endocrine systems. There are biological correlates of behaviour.

Describe the principle

  • Specific brain processes, neurotransmitters, and hormones can play a role in behaviour. 
  • These physiological processes are what forms the basis of the biological level of analysis, in relation to how it functions and therefore affects human behaviour in everyday life. 
    • For example, this relates to the idea of localization of function, in that each area of the brain is responsible for coordinating a certain part of our body/nervous system and thus our behaviour. 

Outline the approaches that can be made towards this principle 

  • This can be viewed using a reductionist approach, i.e. breaking down complex behaviour into smaller parts for analysis. 
  • Or a deterministic approach can be used, which suggests that human behaviour is completely physiological and that we are not capable of “free will?, but by predictable bodily functions, which is also assumes a correlational approach. 

Supporting Study 1: Raine et. al (1997)

Introduce Study/Signpost 

A study which supports this principle was conducted by Adrian Raine (1997), in which he aimed to determine whether... (insert aim here) 


  • The aim of the experiment was to discover (using PET scans) if murderers who pleaded not guilty by reason of insanity (NGRI) showed evidence of brain abnormalities (observing the cortical and subcortical parts of the brain) 


  • The independent variable in this study was whether the participant was a NGRI or not. 
  • The dependent variable was the PET scan results between the controls and the NGRIs. 
  • Controlled: 
    • 1 for each subject
      • matched for age / sex
      • schizophrenics with non-murderer schizophrenics
      • all controls screened for mental/physical health) 


  • 41 participants (39 male, 2 female) who pleaded not guilty for reasons of insanity (average age of 34.3) 
  • 41 participants (controls), selected based on sex, age and matched to a NGRI participant 
  • Each participant was injected with a glucose tracer (bonds to glucose) (for PET scans) 
    • Glucose tracers tracks brain activity as the brain absorbs glucose (as energy) 
    • Radioactive glucose tracer emits positively charged particles called positrons, which are picked up by the scan
    • PET scans show colourful maps of the brain activity; red = most active, blue = least active.
  • They had to perform tasks requiring them to detect target signals for 32 minutes


  • NGRIs had less activity in the pre-frontal cortex
    • Linked to self-control and emotion
  • NGRIs had lower activity in the amygdala and medial temporal hippocampus
  • Lack of inhibition of violent behaviour
  • Fearlessness - Inappropriate emotional expression
  • Failure to learn consequences for violence  
Connection of study to principle

  • Raine showed that there was a difference in brain structure between normal subjects and prisoners that pleaded not guilty for reasons of insanity (NGRI)
    • Subsequently showing how biological factors (brain structure) may thus affect behaviour 
  • This study supports the idea that there are biological correlates of behaviour because it was shown that there was a correlation between the behaviour of aggression and the physiology of the brain. 
The next principle that will be outlined is that

2. Animal research can provide insight into human behaviour

Describe the principle

  • This principle is based on Charles Darwin’s theory of evolution
    • Revolves around the idea that humans and the many animals are different species now because of thousands of years of evolutionary adaptation to environmental demands
    • Natural selection - those who adapt best to environmental challenges will have characteristics better suited to the environment and are more likely to pass on these traits
  • Evolution is attributed as to why humans and some animals share some similar anatomy and behaviour
    • Therefore, inferences about humans can be made from animal research.
  • Many animals, especially monkeys of the ape family have similar bodily systems as ours, so it can be presumed that when put in the same situation; humans would behave similarly to the animals.
  • This idea is useful when testing treatments, although it does raise ethical issues in the treatment of animals, unless it is for a good cause and that it can be applied to humans and their health.

Supporting Study 2: Berthold (1849)

Introduce Study/Signpost

  • An example of a study that used animals as a substitute for humans because of ethical concerns is by Berthold (1849).


  • The aim of this experiment was to test the effects of testosterone in roosters
  • Berthold aimed to test the effects of castration in roosters, with the assumption that “were the action to be performed on humans, the reaction would be similar.?

  • Quasi- experiment 
  • 6 healthy roosters
  • Surgically castrated them (removing testicles thus stopping the production of testosterone) He then divided them into 3 groups of 2 roosters
    • Group 1 - control group- roosters were left in their own capons 
    • Group 2 - transplanted with testicles of another rooster 
    • Group 3 - reimplanted with their own testicles 


  • Berthold observed that the castrated roosters were less masculine, less aggressive
  • Those roosters that reacquired testicles behaved like normal roosters again
  • Autopsy of roosters revealed that the testicles did not re-establish nerve connections with the rest of the body 


  • Berthold concluded that the testicles must have produced a biochemical that influences aggressive behaviour (known as testosterone)
  • The findings to this study support the role of physiological factors - hormones and the endocrine system (specifically for testosterone) in influencing aggressive behaviours 
Connection of study to principle 

  • Berthold’s study demonstrates the principle of the BLA because inferences were made to humans from roosters about the effect of testosterone on behaviour to inform our understanding of aggression (in humans). 
  • It also highlights the importance of using animals to determine human behaviour. 


  • Summarize the significance of studies in supporting the three principles (*do not restate the principles and studies mentioned as this wastes time and are repetitive).
    • It can be seen that there is sufficient support for the principles of the BLA.
    • It can be seen that in all three principles, other factors need to be taken into account before determining these principles as the sole influences of human behaviour.
    • These principles help to guide studies from a biological perspective.
    • Views from all levels of analysis need to be taken into account before reaching a determined decision on influences on human behaviour.