For Schacter, Harvard’s William R. Kenan Jr. Professor, fears that technology is crushing our ability to remember are overblown, though he admits it does seem to have some negative impact on “task-specific effects.”
He cited experiments in which people asked to navigate a simulated route using GPS had poorer recall for the route later on than subjects who didn’t use the satellite-based navigation system to follow the same path. But, he said, there is “little evidence” to suggest the use of GPS negatively affects the ability to retain spatial memories in general, and “no evidence” currently to suggest GPS impairs other kinds of recall, such as memory for facts or everyday events.
Advances in technology have also helped researchers better understand the nature of true memories versus false ones, said Schacter, whose updated book includes entries on the research in the past 20 years involving neuroimaging of the brain. Using functional magnetic resonance imaging (fMRI), Schacter and other scientists have studied which parts of the brain light up when someone correctly remembers a word from a spoken list as opposed to a word they incorrectly recalled as being part of the list, using what’s known as the Deese-Roediger-McDermott paradigm.
Schacter found areas of the brain tied to language and auditory processing showed increased activity, “suggesting that, for the words you actually heard, there was some sort of auditory reactivation that left a kind of a sensory signature of the actual experience,” he said. Another study from his lab showed the same was true for areas of the brain associated with visual information, he said, indicating there’s a “visual sensory signature for shapes that you would actually have seen versus similar-looking shapes that you hadn’t seen, but you thought that you did.”
Many think the work could have far-reaching implications. According to the Innocence Project, 69 percent of the nation’s 375 DNA exonerations have involved some form of misidentification. But Schacter doesn’t think the research is ready for the courtroom, in part because such tests are conducted in highly controlled environments and are checking “memory at brief delays,” instead of over much longer periods of time. They are also mostly using undergraduates, compared with a much more diverse population, he said, and taking the average results across groups of people.
“But in the courtroom, of course, we want to know about an individual’s memory … we want to know about one specific item or event.”
Neuroimaging research is also shining a light on how the brain’s process of remembering is connected to the ways in which our complicated neural networks imagine future scenarios, and even create false memories. Schacter pointed to research in which he and psychologist Donna Rose Addis used fMRI technology to observe the areas of the brain that reacted when they asked subjects to both recall something from their past, and to picture a future event.
“The striking thing to come out of this study was that the brain maps look very similar when you remember a past event compared to a control task, or imagine a future event compared to a control task,” said Smith. He and Addis later surmised the brain uses the “flexible retrieval and recombination of elements of stored episodes to construct possible future episodes.”
But sometimes the process results in mis-combining of elements of past experiences. There is some fMRI evidence, Schacter said, that demonstrates how “this episodic recombination process results in the reinstatement of false neural patterns that can fool us into thinking that we’ve experienced an event that we have not.”
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