Frequency and characteristics of spontaneous memories in Highly Superior Autobiographical Memory (HSAM): a naturalistic single case diary study

It is well documented that individuals who possess a Highly Superior Autobiographical Memory (HSAM) can voluntarily retrieve an increased frequency of personal memories, that are also markedly more detailed, compared to non-HSAM individuals. In contrast, no study has explored potential differences relating to involuntary autobiographical memory (IAM) retrieval. Here, a single HSAM case (DT) and matched controls completed a 1-day naturalistic IAM diary study to investigate frequency and characteristics of IAMs. HSAM individuals, even if they can remember almost every day of their life, are not constantly flooded by their past. Therefore, we hypothesised that occurrence of IAMs would be as in controls. At the same time, their exceptional ability to remember personally-relevant events could be reflected in the features of the memories relived. In line with our predictions, frequentist and Bayesian analyses support that DT has a normal prevalence of spontaneous memory pop-ups, but his IAMs were more vivid and self-relevant than controls. Such results support that, for individuals with exceptional memory, IAMs, like voluntary memories, are of an extremely high quality. Finally, we argue that our results provide evidence in support of cue overload mechanisms limiting unintentional (but possibly also intentional) retrieval in HSAM.