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Outline principles that define the biological level of analysis

Principle 1: There are biological explanations of behavior

This means that there are physiological origins of behavior such as neurotransmitters, hormones, specialized brain areas, and genes. The biological level of analysis is based on reductionism, which is the attempt to explain complex behavior in terms of simple causes.

Study to use: Newcomer et al. (1999)

Principle 2: Animal research can provide insight into human behavior.


This means that researchers use animals to study physiological processes because it is assumed that most biological processes in non-human animals are the same as in humans. One important reason for using animals is that there is a lot of research where humans cannot be used for ethical reasons.

Study to use: Rosenzweig and Bennet (1972)

Principle 3: Human behavior is, to some extent, genetically based.

This means that behavior can, to some extent, be explained by genetic inheritance, although this is rarely the full explanation since genetic inheritance should be seen as genetic predisposition which can be affected by environmental factors.

·         Researchers interested in the genetic origin of behavior often use twins so that they can compare one twin with the other on a variable such as intelligence, depression or anorexia nervosa.

·         Identical twins (monozygotic twins – MZ) are 100% genetically identical as they have developed from the same egg. They therefore act as a control for each other. Fraternal twins (dizygotic twins – DZ) have developed from two different eggs. They share around 50% of their genes so they are no more similar than siblings.