Term 3 - Animal Research - Animal Models

Animal Models

Animal Models:

• An animal model is a concept that refers to using animal research to test a certain cause - effect hypothesis about a certain human behaviour

• The purpose behind research with animals is to gain a deeper understanding of human behaviour

• This rests on the assumption that the structure and chemistry of the brain is, in some cases, very similar in humans and animals

• However, this assumption cannot be said to be fully justified at all times

 

• One of the most contentious issues in science is the use of animals in research

• Psychologists use animal models to gain greater insight into human behaviour and physiology because some research cannot be done with humans

• Over the past few decades, we have seen major changes in how this research is carried out

What animals are used

What animals are used:

• In the USA and the European Union, around 29 million animals are used in experiments yearly

• Rats and mice make up around 80% of the total

• The number of animals used in experiments has fallen by half in the past 30 years

Reasons we use animals to study human behaviour

Reasons we use animals to study human behaviour:

• They are similar to us both genetically and physiologically

• In 2002, geneticists completed the mapping of the rat genome. Researchers found that rats and humans have each about 30,000 genes, and only 300 are unique to either organism --> the genes of these two species are 99% similar

• Many of the differences have to do with gene expression. Humans and rats have a gene responsible for tail development, but this gene is only expressed in rats

• They breed faster than humans, so several generations can be observed over a shorter period

• An animal's lifespan is significantly shorter than a human's, so the effects of a variable, such as stress, can be studied for a full lifetime and over several generations

• This is particularly helpful in the study of neurodegenerative diseases such as Alzheimer's disease

• They can be used for procedures that would be considered unethical for humans - e.g. experimental procedures may be carried out, such as isolation and surgery, that would be unethical for humans

• Procedures can be carried out under highly controlled conditions that would not be possible with human subjects. This increases the internal validity, allowing psychologists to determine causality

4 Experimental Manipulations

4 Experimental Manipulations:

1. Genetic

2. Invasive with CNS

3. Invasive with other body parts

4. Environmental manipulations

What makes a good animal model?

What makes a good animal model?

• Has extensive research been carried out on the biology of this species?

• Are there genetic similarities to humans?

• Are there physiological similarities to humans - e.g. in metabolism or development

• Does the animal have a short life cycle so that generations can be studied?

• Is it relatively easy to provide appropriate living requirements for the animal?

• Are there behavioural analogs to humans? - e.g. much research has been done on anxiety in laboratory animals, which makes it then possible to do anti-anxiety drug testing

Limitations of Animal Research

Limitations of Animal Research:

• External validity - especially with regard to drug therapies, what is observed in animals often does not predict what will happen in humans

• It is questionable whether the animal's physiology leads to this lack of predictability or whether it results from low ecological validity - that is, the highly controlled environment and the way variables are operationalised

• That leads us to question to what extend animal research can be generalised to humans

• An animal model on its own cannot be generalised to humans. The researchers must find evidence in humans that can be explained trough the animal model. However, animal research might lead to inferences about human behaviour. This is called theoretical generalisation

• Animals cannot readily communicate their responses; they can only be observed. This means we cannot know the animal's cognitive processes. It also means that research is open to researcher bias, where the researcher will see what is expected