Highly superior autobiographical memory (HSAM) in a 16-year-old male: Investigating involuntary autobiographical...

Highly Superior Autobiographical Memory (HSAM) is characterized by an exceptional ability to recall personal past events with remarkable accuracy and detail. While the mechanisms underlying this ability have begun to be elucidated, research so far has largely focused mainly on voluntary retrieval processes. The present study aimed to investigate autobiographical memory functioning in a single HSAM case (KCL), with a particular focus on involuntary autobiographical memories (IAMs). We combined standardized HSAM screening procedures with a multi-method assessment of autobiographical memory, implemented remotely under continuous researcher supervision. General autobiographical functioning was assessed using the Autobiographical Recollection Test and the Survey of Autobiographical Memory. Additional measures captured general memory functioning, mind-wandering, metacognitive and phenomenological characteristics, cognitive control, and affective and personality variables. IAMs were assessed using both self-report (Involuntary Autobiographical Memory Inventory) and a laboratory vigilance task with incidental cue-words and probe-caught thought sampling. KCL met established HSAM criteria and exhibited a markedly elevated frequency of IAMs relative to a comparison group, both in self-report and laboratory measures. Crucially, this increase did not reflect a general rise in spontaneous cognition, as overall task-unrelated thought frequency remained comparable, but rather a selective bias toward autobiographical content. At the same time, KCL did not differ from the general population in overall phenomenological experience of remembering, although he reported elevated autobiographical memory ability alongside increased confidence in memory accuracy. The results highlight the central role of involuntary remembering and point to altered cue sensitivity and lowered retrieval thresholds as key mechanisms underlying exceptional autobiographical memory.