Linking Detail to Temporal Structure in Naturalistic-Event Recall.

Decades of memory research demonstrate the importance of temporal organization in recall dynamics, using laboratory stimuli (i.e., word lists) at seconds- to minutes-long delays. Little is known, however, about such organization in recall of richer and more remote real-world experiences, in which the focus is usually on memory content without reference to event order. Here, 119 younger and older adults freely recalled extended real-world experiences, for which the encoding sequence was controlled, after 2 days or 1 week. We paired analytical tools from the list-learning and autobiographical memory literatures to measure spontaneous contextual dynamics and details in these recall narratives. Recall dynamics were organized by temporal context (contiguity and forward asymmetry), and organization was reduced in older age, despite similar serial position effects and recall initiation across age groups. Across participants, organization was positively associated with richness of episodic detail, providing evidence for a link between reexperiencing past events and reinstating their spatiotemporal context.

The Truth Is Out There: Accuracy in Recall of Verifiable Real-World Events.

How accurate is memory? Although people implicitly assume that their memories faithfully represent past events, the prevailing view in research is that memories are error prone and constructive. Yet little is known about the frequency of errors, particularly in memories for naturalistic experiences. Here, younger and older adults underwent complex real-world experiences that were nonetheless controlled and verifiable, freely recalling these experiences after days to years. As expected, memory quantity and the richness of episodic detail declined with increasing age and retention interval. Details that participants did recall, however, were highly accurate (93%-95%) across age and time. This level of accuracy far exceeded comparatively low estimations among memory scientists and other academics in a survey. These findings suggest that details freely recalled from one-time real-world experiences can retain high correspondence to the ground truth despite significant forgetting, with higher accuracy than expected given the emphasis on fallibility in the field of memory research.

Vividness of recollection is supported by eye movements in individuals with high, but not low trait autobiographical memory.

There are marked individual differences in the recollection of personal past events or autobiographical memory (AM). Theory concerning the relationship between mnemonic and visual systems suggests that eye movements promote retrieval of spatiotemporal details from memory, yet assessment of this prediction within naturalistic AM has been limited. We examined the relationship of eye movements to free recall of naturalistic AM and how this relationship is modulated by individual differences in AM capacity. Participants freely recalled past episodes while viewing a blank screen under free and fixed viewing conditions. Memory performance was quantified with the Autobiographical Interview, which separates internal (episodic) and external (non-episodic) details. In Study 1, as a proof of concept, fixation rate was predictive of the number of internal (but not external) details recalled across both free and fixed viewing. In Study 2, using an experimenter-controlled staged event (a museum-style tour) the effect of fixations on free recall of internal (but not external) details was again observed. In this second study, however, the fixation-recall relationship was modulated by individual differences in autobiographical memory, such that the coupling between fixations and internal details was greater for those endorsing higher than lower episodic AM. These results suggest that those with congenitally strong AM rely on the visual system to produce episodic details, whereas those with lower AM retrieve such details via other mechanisms.

Different patterns of recollection for matched real-world and laboratory-based episodes in younger and older adults.

To bridge the gap between naturalistic and laboratory assessments of episodic memory, we designed time- and content-matched real-world and virtualized versions of the same tour event. In younger and older adults, we investigated objective and subjective aspects of recollection for event features using a verbal true/false test common to both event conditions. Using a data-driven multivariate analysis blind to the age groups and event conditions, we found that discriminating altered from true details accounted for the largest amount of variance in objective retrieval patterns. There was an advantage for real-world over laboratory encoding on this dimension for both age groups. Similarly, real-world encoding elicited higher scores on a dimension defined by subjective recollection. However, real-world (but not laboratory) encoding decoupled objective and subjective memory in older adults, who reported similar rates of subjective recollection as younger adults despite exhibiting significantly poorer discrimination accuracy. These results demonstrate robust and specific ways in which the accuracy and subjective quality of memory differ for matched naturalistic and laboratory episodes. Furthermore, these results suggest that naturalistic and laboratory encoding conditions produce qualitatively different patterns of episodic memory decline in older age.

Classification of general and personal semantic details in the Autobiographical Interview.

The Autobiographical Interview (AI) separates internal (episodic) and external (non-episodic) details from transcribed protocols using an exhaustive and reliable scoring system. While the details comprising the internal composite are centered on elements of episodic memory, external details are more heterogeneous as they are meant to capture a variety of non-episodic utterances: general semantics, different types of personal semantics details, metacognitive statements, repetitions, and details about off topic events. Elevated external details are consistently observed in aging and in neurodegenerative diseases. In the present study, we augmented the AI scoring system to differentiate subtypes of external details to test whether the elevation of these details in aging and in frontotemporal lobar degeneration (including mixed frontotemporal/semantic dementia [FTD/SD] and progressive non-fluent aphasia [PNFA]) would be specific to general and personal semantics or would concern all subtypes. Specifically, we separated general semantic details from personal semantic details (including autobiographical facts, self-knowledge, and repeated events). With aging, external detail elevation was observed for general and personal semantic details but not for other types of external details. In frontotemporal lobar degeneration, patients with FTD/SD (but not PNFA) generated an excess of personal semantic details but not general semantic details. The increase in personal but not general semantic details in FTD/SD is consistent with prevalent impairment of general semantic memory in SD, and with the personalization of concepts in this condition. Under standard AI instructions, external details were intended to capture off-topic utterances and were not intended as a direct measure of semantic abilities. Future investigations concerned with semantic processing in aging and in dementia could modify standard instructions of the AI to directly probe semantic content.

Age-related decline in item but not spatiotemporal associative memory for a real-world event.

Normal aging is typically associated with reduced ability to reconstruct the spatiotemporal context of past events, a core component of episodic memory. However, little is known about our ability to remember the order of events comprising extended real-world experiences and how this ability changes with age. We leveraged the richness and structure of a museum exhibit to address this question. Three months after visiting the exhibit, 141 adults aged 18-84 completed a test of spatiotemporal order memory and old/new recognition using pictures from the exhibit and similar lures, from which measures of associative and item memory were derived. Order discrimination accuracy was modulated by interitem order and distance in younger and older adults, extending findings from recognition of laboratory stimuli at short delays to remote real-world experiences. In contrast to established findings from laboratory-based assessments, we observed a significant effect of aging on item memory driven by increased lure susceptibility, but no age-related reduction in spatiotemporal associative memory. These findings present novel insights into different components of memory for real-world experiences at naturalistic timescales and across the lifespan. (PsycINFO Database Record (c) 2018 APA, all rights reserved).