2.5 The duration of solitary confinement All studies of prisoners who have been detained involuntarily in solitary confinement in regular prison settings for longer than ten days have demonstrated some negative health effects (Haney, 2003), and even apologists of the practice agree that prolonged punitive solitary confinement “presents considerable risk to the inmates” (Gendreau and Bonta, 1984:475). A study comparing subsequent admission to psychiatric hospitals in Denmark for prisoners held in solitary confinement compared to those held with other prisoners, found that hospitalisation rates diverged significantly after four weeks. The “probability of being admitted... for psychiatric reasons was about 20 times as high as for a person remanded in non-solitary confinement for the same period of time” (Sestoft et al. 1998:105). Siegel’s (1984) study of 31 people who were subjected to isolation, visual deprivation and restraint on physical movement in different situations (hostages, POWs, prisoners) and for varying times reported visual and auditory hallucinations within hours of being isolated, becoming more severe with time. Studies with volunteer prisoners isolated for periods of up to ten days have commonly reported minimal negative effects. Walters et al (1963:772) noted that for 20 long-term prisoners in a Canadian Federal Penitentiary who volunteered to stay in solitary cells for four days “while social isolation may produce some change in subjective feelings, it does not result in mental or psychomotor deterioration or increased susceptibility to social influence.” Similarly Ecclestone, Gendreau and Knox in 1974 reported that for eight volunteers over a period of 10 days “solitary confinement was not more stressful than normal institutional life.” But these outcomes may be accounted for by the short duration of stay in isolation and by the fact that prisoners who participated in these studies welcomed the opportunity to spend time away from the general prison population Experimental studies with volunteers have reported relatively short-lived tolerances for isolation. Although such studies are not equivalent to enforced isolation in the prison context where prisoners are not free to end the experiment at any time, the findings serve to illustrate the powerful impact of isolation on human subjects. In a study aimed at measuring levels of tolerance to isolation, approximately two-thirds of the volunteers were able to remain in an isolated room for periods ranging from three to fourteen days (Zuckerman, 1964:255-276). In another, twenty volunteers were placed separately in a silent room, and asked to remain in it for as long as they could. The average quitting times were 29.24 hours for men and 48.70 hours for women. None of the participants endured the ‘silent room’ for longer than four days (Smith & Lewty, 1959:342-345). Where the duration of isolation was unspecified, two hours were sufficient to generate confusion and the fear of becoming insane (Solomon et al, 1961). Other studies have also demonstrated that an important element in the level of endurance of solitary confinement is prior knowledge of its duration. Uncertainty as to its duration “promotes a sense of helplessness. Finite sentences imposed for acknowledged acts seem less prone to inspire panic” (Toch, 1992:250). Another study concluded that uncertainty is a critical factor relating to the outcome of hostility and aggression (McCleery 1961:303). Knowing how long the experience is to last is therefore a clear mitigating factor available to those responsible for placing a prisoner in segregation. Sourcebook on solitary confinement: The health effects of solitary confinement 21