Summary: A new study reveals people are able to recognize images they have only seen for a few seconds up to 10 years after exposure.
Recalling the names of old classmates 50 years after graduation or of favorite childhood television series illustrates the amazing abilities of human memory. Emotion and repeated exposure are both known to play a role in long-term memorization, but why do we remember things that are not emotionally charged and have only been seen or experienced a few times in the past? To answer this question, scientists from the Centre de recherche cerveau & cognition research unit (CNRS/Université Toulouse III—Paul Sabatier)1 decided to challenge the memory of individuals they had tested in the laboratory a decade previously. They discovered that participants recognized images seen for only a few seconds ten years earlier. These findings were published online on November 5, 2017, in Cognition.
When conducting laboratory tests, it is difficult to account for key factors involved in memorization. Yet it is known that frequent exposure to sensory data translates into durable memories. And that something seen or experienced only once might never be forgotten when strong emotions are involved.
The researchers in this study were able to control for these variables—i.e., emotional context and number of exposures—and evaluate another type of memorization. They asked 24 people (having no memory disorders) tested in the laboratory ten years previously to return for new tests. A decade earlier, the same individuals had been shown a sequence of simple clipart images, each for only a few seconds, without being given any particular instructions to memorize them. When they returned to the lab in 2016, participants were asked to identify these pictures presented in pairs alongside new images.
On average, those surveyed obtained 55% correct answers, compared with 57% in the case of images already seen at least three times and up to 70% for some participants (one third of whom scored between 60% and 70%).
Under these experimental conditions, it seems that three exposures are sufficient to memorize an image for 10 years. Although scientists have known for several years that memories can be retained implicitly—that is, without being able to consciously access them—this new study shows that they can directly influence participants’ choices and may sometimes even provoke a strong feeling of familiarity.
The researchers are now seeking to elucidate the biological basis for this memorization. They hypothesize that such memories rely on a small group of ultraspecialized neurons rather than a wide and diffuse neuronal network.
About this neuroscience research article
1The study team also included a researcher from the Institut de neurosciences des systèmes (AMU/INSERM)
Source:CNRS Publisher: Organized by NeuroscienceNews.com. Image Source: NeuroscienceNews.com image is in the public domain. Original Research: Full open access research for “Extremely long-term memory and familiarity after 12 years” by Christelle Larzabal, Eve Tramoni, Sophie Muratot, Simon J. Thorpe, and Emmanuel J. Barbeau in Cognition. Published online November 5 2017 doi:10.1016/j.cognition.2017.10.009
[cbtabs][cbtab title=”MLA”]CNRS “Our Amazing Ability to Recognize Images Seen Briefly 10 Years Later.” NeuroscienceNews. NeuroscienceNews, 13 November 2017. <https://neurosciencenews.com/longterm-image-memory-7931/>.[/cbtab][cbtab title=”APA”]CNRS (2017, November 13). Our Amazing Ability to Recognize Images Seen Briefly 10 Years Later. NeuroscienceNews. Retrieved November 13, 2017 from https://neurosciencenews.com/longterm-image-memory-7931/[/cbtab][cbtab title=”Chicago”]CNRS “Our Amazing Ability to Recognize Images Seen Briefly 10 Years Later.” https://neurosciencenews.com/longterm-image-memory-7931/ (accessed November 13, 2017).[/cbtab][/cbtabs]
Extremely long-term memory and familiarity after 12 years
In 2006 Mitchell demonstrated that implicit memory was robust to decay. He showed that the ability to identify fragments of pictures seen 17 years before was significantly higher than for new stimuli. Is this true only for implicit memory? In this study, we tested whether explicit memory was still possible for drawings (n = 144) that had been presented once or three times, two seconds each time on average, approximately 12 years earlier. Surprisingly, our data reveal that our participants were able to recognize pictures above chance level. Preserved memory was mainly observed in the youngest subjects, for stimuli seen three times. Despite the fact that confidence judgments were low, reports suggest that recognition could be based on a strong sense of familiarity. These data extend Mitchell’s findings and show that familiarity can also be robust to decay.
“Extremely long-term memory and familiarity after 12 years” by Christelle Larzabal, Eve Tramoni, Sophie Muratot, Simon J. Thorpe, and Emmanuel J. Barbeau in Cognition. Published online November 5 2017 doi:10.1016/j.cognition.2017.10.009