"The fallibility, and malleability, of memory is old news to anyone who has ever had his vivid recall of a third-birthday party shattered by a grainy old home movie."
Human memory does not work like a video camerait is far from completely reliable, says UW psychology professor Elizabeth F. Loftus. People may mingle memories of different events, fill in gaps, or create memories based on suggestion.
Pioneering research conducted by Loftus at the UW over the past 20 years has documented such cases and probed the mechanisms by which false memories occur. She has conducted hundreds of psychological experiments which indicate that after people first see an event—for example, a crime or an accident—the memory of the event subsequently can be altered. New, post-event information can become incorporated into memory to supplement or change it. In her studies, people have recalled a clean-shaven man as having a mustache; straight hair as curly, and even a barn where no buildings stood at all.
In one project, Loftus studied the creation of false memories about childhood events. Parents of the participants cooperated in producing a list of events that had occurred to the participants during childhood. Three of the events actually occurred, according to the parents, but one was a fabricated account about the child becoming lost on a shopping trip. Results of the study showed that about 10% of adults will come up with a specific "elaborated " memory of the fictitious childhood event, believing it actually occurred. Another 15% will produce a partial memory of the fictitious event.
Data gathered by Loftus and others are helping neurologists and cognitive scientists determine how the brain functions to create these malleable memories. The current hypothesis is "source amnesia," the inability to recall the origin of the memory of a given event. Once that source is forgotten, people can confuse imagined or suggested events with the true one. Those with damage to specific sites in the frontal lobes are especially prone to concocting or altering memories.
Memories of an event apparently are stored in several different parts of the brain. For example, memories of sound are stored in the auditory cortex, and those of appearance in the visual cortex. The scattered pieces of the memory remain linked through a part of the brain called the limbic system. "Like a neural file clerk," the limbic system pulls disparate aspects of a memory together from storage sites throughout the brain, integrating them into a whole. Altered memories can occur when people recall accurate pieces but assemble them incorrectly, or wrongly attribute an origin to a particular set of memory fragments.
Loftus's work on memory has important implications for evaluating the reliability of eyewitness testimony in court proceedings. The results also have contributed to a growing controversy over the validity of techniques in psychotherapy which use hypnosis or regression—recalling, imagining, or reliving events from an earlier time. These techniques may mix suggestion or imagination with memories; once mixed, they are next to impossible to separate, say some scientists.