Examining phantom sensations also reinforces the principle of brain plasticity: the brain's capacity for reorganization. Angela's right arm has been amputated. She reports that she retains feeling in her nonexistent hand, which feels as though it is attached to the remaining stump. As researcher Peter Halligan stimulates different spots on Angela's stump, she reports specific sensations in the fingers of her missing hand. The brain area that once received sensations from her missing fingers is still intact and thus can still represent the experience of stimulation. As the investigator touches Angela's face, she reports sensations in her hand. The brain area receiving signals from Angela's face has actually spilled over into the brain area that once received signals from her hand.