April 12, 2010 -- Emotions may persist long after the actual memory of an experience dies, a new study finds.
Researchers found that people with severe amnesia continued to experience elevated levels of sadness or happiness after watching a sad or happy movie clip, even though they couldn’t remember what they had seen.
"Indeed, they still felt the emotion. Sadness tended to last a bit longer than happiness, but both emotions lasted well beyond their memory of the films," researcher Justin Feinstein, a doctoral student in clinical neuropsychology at the University of Iowa, says in a news release.
"A simple visit or phone call from family members might have a lingering positive influence on a patient's happiness, even though the patient may quickly forget the visit or phone call," Feinstein says. "On the other hand, routine neglect from staff at nursing homes may leave the patient feeling sad, frustrated, and lonely, even though the patient can't remember why."
In the study, published in the Proceedings of the National Academy of Sciences, researchers evaluated five people with severe amnesia from damage to their hippocampus, the part of the brain that converts short-term memories into long-term ones. Damage to this part of the brain causes new memories to disappear, which is also an early sign of Alzheimer’s disease.
The participants were shown 20 minutes of either sad or happy movie clips on different days. About 10 minutes after the clip ended, they were tested to see if they could recall what they had watched.
As expected, the participants remembered few, if any, details of the movie clips. But when asked questions to gauge their emotional state, researchers found the participants continued to experience feelings of sadness or happiness long after their factual memory of the experience faded.
Researchers say the results challenge the notion that erasing a painful memory can stop emotional suffering and has major implications for Alzheimer’s care.
"What this research suggests is that we need to start setting a scientifically informed standard of care for patients with memory disorders,” Feinstein says. "Here is clear evidence showing that the reasons for treating Alzheimer's patients with respect and dignity go beyond simple human morals."