there have been studies that have shown no difference between inmates in solitary confinement and those in normal lockup. for example, "effect of solitary confinement on prisoners" examines a study that compared twenty prison inmates that were put into isolation to twenty inmates from general population that were used as the controls. the subjects were tested immediately before and after being put into isolation and the results showed that although there was a slight difference in subjective feelings, there were no mental or psychomotor changes. "effect of solitary confinement on prisoners" argues that the negative effects of solitary have often been overemphasized and that the reason these negative findings are often reported is due to the characteristic difference between those who end up in solitary confinement and those who do not.