A behavioral abnormality whereby a person is unable to move freely from one situation, activity or aspect of aa problem to another as circumstances demand. Key aspects of shifting include the ability to make transitions, problem solve flexibly, switch or alternate attention, and change focus from one mind-set or topic to another. Mild deficits in the ability to shift compromise the efficiency of problem solving, whereas more severe difficulties are reflected in perseverative behaviors. Sometimes this is described as being rigid or inflexible. [from
HPO]