We all have the ability to maintain and process information in our working memory, though some individuals have a greater working memory capacity than others. Everyday tasks are well within the normal person's working memory capacity, but at times, a great demand on mental resources will cause performance to be compromised. These studies examine how motor performance, such as hand movements, can be impaired by performing mental tasks. Also, different types of mental tasks are related to different degrees of compromised motor performance. Individuals may show differences in their abilities based not only on their working memory capacity, but on previous experiences that allow familiar tasks to consume fewer mental resources. In some situations, such as driving a car or performing surgery, even a small degradation of motor performance can have severe consequences. These experiments should be useful not only to memory researchers, but to anyone interested in how our physical movements can suffer as the result of various mental demands.