equipotentiality

Equipotentiality refers to a psychological theory in both neuropsychology and behaviorism. Karl Spencer Lashley defined equipotentiality as "The apparent capacity of any intact part of a functional brain to carry out… the [memory] functions which are lost by the destruction of [other parts]". In other words, the brain can co-opt other areas to take over the role of the damaged part. Equipotentiality is subject to the other term Lashley coined, the law of mass action. The law of mass action says that the efficiency of any complex function of the brain is reduced proportionately to how much damage the brain as a whole has sustained, but not to the damage of any particular area of the brain. In this context when we use our brains we are referring to the cortex.

==Historical context== In the 1800s brain localization theories were the popular theories on how the brain functioned. The Broca's area of speech was discovered in 1861, in 1870 the cerebral cortex was marked as the motor center of the brain, and the general visual and auditory areas were defined in the cerebral cortex. Behaviorism at the time would also say that learned responses were series of specific connections in the cerebral cortex. Lashley argued that one would then be able to locate these connections in part of the brain and he systematically looked for where learning was localized.