People need not only to obtain things, they need above all the freedom to make things among which they can live, to give shape to them according to their own tastes, and to put them to use in caring for and about others. Prisoners in rich countries often have access to more things and services than members of their families, but they have no say in how things are to be made and cannot decide what to do with them. Their punishment consists in being deprived of what I shall call “conviviality.” They are degraded to the status of mere consumers.
First They Came for the Horses | Front Porch Republic
Note: This is not meant to imply that the main loss of freedom for prisoners is in how they relate to objects. This is only secondary to their isolation from their community and the regimentation of their times. And of course, that is only considering the "official" hardships of prison life, not the threat of violence from other prisoners and guards.