Comparative Psychology

Comparative psychology is the study of animals in order to find out about humans. The underlying assumption is that to some degree the laws of behavior are the same for all species and that therefore knowledge gained by studying rats, dogs, cats and other animals can be generalised to humans.

There is a long history of experimentation on animals and many new drugs and cosmetics were first tested on non-humans to see what their effects were. If there were no obvious harmful side effects then human trials would often follow.

In psychology the method is often favoured by those who adopt a nomothetic approach (e.g. Behaviorism and the biological approach ).

For example the behaviorists argued that the laws of learning were the same for all species. Pavlov’s (1897/1902) studies of classical conditioning in dogs and Skinner’s studies of operant conditioning in rats are therefore seen as providing insights into human psychology. Some would even go so far as to claim that the results of such studies provide a justification for reorganising the way in which we teach children in schools.

Another application of comparative psychology is in the study of child development . Konrad Lorenz and Harry Harlow are just two of the best-known researchers into the effects of maternal deprivation.

Lorenz (1935) studied imprinting in ducks and geese. He found that there was a critical period in infancy when the duckling would become attached and that if this window of opportunity were missed it would not become attached in later life.

Harlow (1958) found that infant rhesus monkeys that were separated from their mothers (and from all other monkeys) suffered irreversible social and emotional damage.

Many psychologists have argued that human infants also have a critical attachment period and that they too suffer permanent long-term damage if they are separated from their attachment figure.


In some respects humans are similar to other species. For example we exhibit territoriality, courtship rituals, a “pecking order”. We defend our young, are aggressive when threatened, engage in play and so on.

Many parallels can therefore be drawn between ourselves and especially other mammals with complex forms of social organisation.

Studying other species often avoids some of the complex ethical problems involved in studying humans. For example one could not look at the effects of maternal deprivation by removing infants from their mothers or conduct isolation experiment on humans in the way that has been done on other species.


Although in some respects we are like other species in others we are not. For example humans have a much more sophisticated intelligence than other species and much more of our behavior is the outcome of a conscious decision than the product of an instinct or drive.

Also humans are unlike all other species in that we are the only animal to have developed language. Whist other animals communicate using signs we use symbols and our language enables us to communicate about past and future events as well as about abstract ideas.

Many people would argue that experimenting on animals is completely ethically reprehensible. At least human subjects can give or withhold their consent. The animals used in some pretty awful experiments didn’t have that choice.

Also, what have we gained from all the suffering we have inflicted on these other species. Critics argue that most of the results are not worth having and that the ends do not justify the means.


Harlow, H. F. & Zimmermann, R. R. (1958). The development of affective responsiveness in infant monkeys. Proceedings of the American Philosophical Society, 102,501 -509.

Lorenz, K. (1935). Der Kumpan in der Umwelt des Vogels. Der Artgenosse als auslösendes Moment sozialer Verhaltensweisen. Journal für Ornithologie, 83, 137–215, 289–413.

Pavlov, I. P. (1897/1902). The work of the digestive glands. London: Griffin.

Olivia Guy-Evans

BSc (Hons), Psychology, MSc, Psychology of Education

Associate Editor for Simply Psychology

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

Saul Mcleod, PhD

Educator, Researcher

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, Ph.D., is a qualified psychology teacher with over 18 years experience of working in further and higher education.