Highly Superior Autobiographical Memory (HSAM) in a 16-Year-Old Male: Investigating Involuntary Autobiographical Memory With Questionnaire and Laboratory Methods

Highly Superior Autobiographical Memory (HSAM) is characterized by an exceptional abilityto recall personal past events with remarkable accuracy and detail. While the mechanismsunderlying this ability have begun to be elucidated, research so far has largely focused mainlyon voluntary retrieval processes. The present study aimed to investigate autobiographicalmemory functioning in a single HSAM case (KCL), with a particular focus on involuntaryautobiographical memories (IAMs). We combined standardized HSAM screening procedureswith a multi-method assessment of autobiographical memory. General autobiographicalfunctioning was assessed using the Autobiographical Recollection Test (ART) and the Surveyof Autobiographical Memory (SAM). Additional measures captured general memoryfunctioning, mind-wandering, metacognitive and phenomenological characteristics, cognitivecontrol, and affective and personality variables. IAMs were assessed using both self-report(Involuntary Autobiographical Memory Inventory; IAMI) and a laboratory vigilance task withincidental cue-words and probe-caught thought sampling. KCL met established HSAM criteriaand exhibited a markedly elevated frequency of IAMs relative to a comparison group, both inself-report and laboratory measures. Crucially, this increase did not reflect a general rise inspontaneous cognition, as overall task-unrelated thought frequency remained comparable, butrather a selective bias toward autobiographical content. At the same time, KCL did not differfrom the general population in overall phenomenological experience of remembering, althoughhe reported elevated autobiographical memory ability alongside increased confidence inmemory accuracy. The results highlight the central role of involuntary remembering and pointto altered cue sensitivity and lowered retrieval thresholds as key mechanisms underlyingexceptional autobiographical memory.