Abstract
One of the most amazing features of our brain is its capacity to retain sensory memories for years or even decades. For example, people may recognize the names or faces of classmates fifty years after they have left school (Bahrick et al., 1975) or the title of TV programs fifteen years after their broadcast (Squire et al. 1975). In such cases, it is quite possible that the memories have been reactivated in the intervening period. For instance, people may have seen their classmates more recently, or seen a repeat of the TV program. But are those re-exposures really necessary to hold a memory for decades? Would people still be able to recognize stimuli when we can be certain that it is impossible that they could have experienced the stimulus more recently? To address this question we designed an experiment in which thirty four participants were shown the opening sequence of 50 TV programs that had been broadcast on French television between the late 50s and early 70s. They have not been rebroadcast since and are not available in the public domain. Based on the percentage of correct responses and the confidence level across participants seven videos were identified as being recalled. Performed on a single case level 15 extra clips were also correctly remembered by at least one of the participants which brings the total to 22 videos positively remembered. This study provides new evidence that it is possible to reactivate memories that were encoded several decades ago, sometimes more than 50 years, without the need for re-exposure in the intervening period. This puts severe constraints on the biological mechanisms that could allow such extreme long-term memories.
Meeting abstract presented at VSS 2015