Observations show that social deprivation has a direct impact on how the body functions. George Engel & Franz Reichsman publish a description of depression in ‘Monica’, an infant whose malformed digestive tract required that she have a drainage tube in her stomach.

While the infant is in the hospital waiting for surgery, Engel and his colleagues take careful observations of her behavior and measure her gastric secretions during different moods. They find that when the child appears happy and relaxed and is surrounded by familiar people, her gastric secretions flow copiously. When she is alone in a sterile, deprived environment or with strangers and appears sad, anxious and withdrawn, her gastric secretions stop.

This is the first time a measurable physiological function is shown to change in relation to deprivation and a mental state. This deprivation research is the counterpart to Hans Selye’s research on stress and over-stimulation.