Double dissociation is a phenomenon in which two distinct behaviors are found to be inversely related. This concept has been used widely in neuroscience research to demonstrate that different brain regions are responsible for distinct aspects of behavior. For example, a double dissociation can be used to show that damage to a particular brain region affects one behavior, while leaving another behavior relatively unaffected. This phenomenon has been used to demonstrate the involvement of different brain regions in various cognitive and motor functions, including language, memory, and motor control (Tranel, Damasio, & Damasio, 1997).
The double dissociation phenomenon is typically studied through the use of two different patient populations. For instance, one group of patients may have damage to a particular brain region, while the other group of patients does not have this damage. Then, each group is studied to determine the effects of the particular brain region on behavior. This type of study is often used to demonstrate that one behavior is selectively impaired in the group with the damaged brain region, while the other behavior is preserved in this group. Therefore, the double dissociation phenomenon can provide strong evidence for the involvement of certain brain regions in particular behaviors (McCarthy & Warrington, 1990).
In addition to being used to study the effects of brain damage, double dissociation has also been used to explore the effects of genetic variation on behavior (Gottesman & Shields, 1982). For instance, a double dissociation approach can be used to compare the effects of two different genotypes on behavior. This type of study can be used to demonstrate the involvement of certain genes in particular aspects of behavior. For example, a study of the effects of two different genotypes on language performance can be used to demonstrate the involvement of certain genes in language processing (Lai et al., 2010).
Overall, double dissociation is a useful concept for demonstrating the involvement of particular brain regions or genes in behavior. By studying the effects of damage to a particular brain region or genetic variation on behavior, researchers can gain insight into the neural and genetic underpinnings of behavior.
References
Gottesman, I. I., & Shields, J. (1982). Schizophrenia and genetics: A twin study. New York: Academic Press.
Lai, C. S., Fisher, S. E., Hurst, J. A., Vargha-Khadem, F., & Monaco, A. P. (2010). A forkhead-domain gene is mutated in a severe speech and language disorder. Nature, 413(6855), 519–523. doi:10.1038/nature08459
McCarthy, R. A., & Warrington, E. K. (1990). Double dissociations in memory functions: Evidence from focal lesion studies. Brain, 113(Pt 6), 1545–1559.
Tranel, D., Damasio, H., & Damasio, A. R. (1997). A neural basis for the retrieval of conceptual knowledge. Neuroscience, 79(3), 993–1004.