It is now well established in psychological research that humans can form false memories – memories for events that never occurred. Further, these false memories are indistinguishable from genuine memories. Questions remain, however, about the neuroanatomical basis of false memories.
One potential window into this question are subjects with so-called “Highly Superior Autobiographical Memory” (HSAM). HSAM itself is a fascinating topic – there are people who can remember many details about specific days in their past. You can ask them, what were you doing on December 9, 2012, and they can think back and tell you, “it was raining and I forgot to bring my umbrella, and I was late for work.” For details you can check, like whether or not it was raining on that day, their details check out.
A new study explores whether or not you can generate false memories in people with HSAM. This may tell us something about HSAM and false memories.
They used standard false memory tests. In one test you show the subject a list of words that all have a theme, for example words that all relate to sweet foods. You then show them a list of words and have them choose which words they can confidently remember from the previous slide. Among the new list of words is “sweet”, which was suggested but never listed in the original set of words (called a “lure word”). A significant number of people will have a false memory of seeing the word “sweet” on the previous slide.
Another false memory test is to suggest an experience that someone never had, by describing it in vivid detail. At a later time some subjects may remember the experience as if they had it themselves – they have personalized the memory.
Yet another study type tries to implant misinformation by asking suggestive questions about pictures that were recently viewed.
The question is – do subjects with HSAM form false memories the same way non-HSAM people do? Does the mechanism of their HSAM protect them from false memories?
The answer – no. The study found that:
HSAM participants and controls were both susceptible to false recognition of nonpresented critical lure words in an associative word-list task. In a misinformation task, HSAM participants showed higher overall false memory compared with that of controls for details in a photographic slideshow. HSAM participants were equally as likely as controls to mistakenly report they had seen nonexistent footage of a plane crash.
So overall the HSAM subjects were as or more susceptible to false memories as typical controls. What does this say about HSAM and false memories? That’s a good question that will require further research.
What we know now about HSAM is that people with this heightened autobiographical memory do not necessarily have enhanced memories for other types of information. We also know that they have increased white matter connections in those parts of the brain carrying autobiographical memory. It is not yet known if they have HSAM because of these increased connections or if they developed increased connections because they developed HSAM.
Regarding false memory, it is believed that they come into play during the reconstructive process of memory. Memories are not so much recalled as reconstructed. Every time you remember something you are reconstructing the memory from various details and themes stored in your long term memory. To construct the overall memory from these parts, and it is probably during this process that false details creep in.
Your brain tries to construct a consistent, plausible, and emotionally gratifying narrative. The details support the overall narrative, but they also can be created or morphed to comply with the larger themes of the narrative. If the theme of the words you just saw was sweetness, then it is likely that the word “sweet” was among them. That mugger was menacing and dangerous, so he probably was holding a gun.
What this study suggests is that those with HSAM may have superior memory for autobiographical details, but they still have to reconstruct memories from those details and this reconstruction process is just as flawed and susceptible to false memories as people with more typical memories.
Understanding memory is critical to metacognition – understanding the process of thought itself. We rely every day on our memories, which are highly flawed and susceptible to distortion. In casual everyday interaction, most people I meet have a dramatic overconfidence in their own memories. They feel that if they can clearly or vividly remember something, it must be accurate.
Meanwhile, psychological research shows that memory is constructed of many different parts – thematic memory, detail memory, event memory, autobiographical, source memory, and truth status, to give some examples. These types of memory can vary independently. We might remember, for example, that we heard something but forget whether or not it was true and where we heard it.
All of these memory components are ultimately woven together into a narrative in a reconstructive process. That seems to be the weakest link in the memory chain – the act of remembering itself alters the memory.
Our memories are evolving narratives. They change as we change, are updated as our knowledge and world-view change.
We cannot rely on our memories. The only solution is to reground your memories in objective external unchanging sources.