Langer, E., & Rodin, J., The effects of choice and enhanced personal reponsibility for the aged: A field experiment in an institutional setting. JPSP, 1976, 191-198.

This study was on the effects of allowing personal decision making among nurshing home residents (in the care of a plant).

"The ability to sustain a sense of personal control in old age may be greatly influenced by societal factors, and this in turn may affect one's physical well being" "more successful aging -- occurs when a individual feels a sense of usefulness and purpose"

A feeling of helplessness may contribute to psychological withdrawal, disease, and death.

Procedure
They selected two floors of a nursing home. One group was told the staff was there to help them. Despite the care, 71% got worse in only 3 weeks. In the other floor where they were encouraged to make decisions for themselves, the residents actually improved. They were more active and happier. They were more mentally alert and more active in activities.