Episodic Memory

Recall decreases across a series of subspan immediate-recall trials but rebounds if the semantic category of the words is changed, an example of release from proactive interference (RPI). The size of the rebound depends on the semantic categories used and ranges from 0% to 95%. We used a corpus of novels to create vectors representing the meaning of about 40,000 words using the BEAGLE algorithm. The distance between categories and spread within categories jointly predicted the size of the RPI. We used a holo-graphic model for recall equipped with a lexicon of BEAGLE vectors representing the meaning of words. The model captured RPI using a hologram as an interface to bridge information from episodic and semantic memory; it is the first account of RPI to capture release at the level of individual words in categorized lists.

The prevailing view about our memory skills is that they serve a complex epistemic function. I shall call this the “monistic view.” Instead of a monistic, exclusively epistemic approach, I propose a transactional view.  On  this  approach,  autobiographical  memory  is  irreducible  to  the  epistemic  functions  of  episodic memory because of its essentially moral and empathic character. I argue that this transactional view provides  a  more  plausible  and  integral  account  of  memory  capacities  in  humans,  based  on  theoretical  and empirical  reasons.  Memory,  on  this  account,  plays  two  distinctive  roles.  The  episodic  memory  system satisfies  epistemic  needs  and  is  valuable  because  it  is  a  source  of  justification  for  beliefs  about  the  past. Autobiographical  memory  satisfies  moral  and  narrative-autonoetic  needs,  and  is  valuable  because  it  is a  source  of  personally  meaningful  and  insightful  experiences  about  our  past. Unlike  autobiographical  memory, episodic memory is only weakly autonoetic. The relation between these two roles of memory is captured by the tension between a narrative and an accurate report.

Elevated prefrontal cortex activity is often observed in healthy older adults despite declines in their memory and other cognitive functions. According to one view, this activity reflects a compensatory functional posterior-to-anterior shift, which contributes to maintenance of cognitive performance when posterior cortical function is impaired. Alternatively, the increased prefrontal activity may be less efficient or less specific, owing to structural and neurochemical changes accompanying aging. These accounts are difficult to distinguish on the basis of average activity levels within brain regions. Instead, we used a novel model-based multivariate analysis technique, applied to two independent functional magnetic resonance imaging datasets from an adult-lifespan human sample (N=123 and N=115; approximately half female). Standard analysis replicated the age-related increase in average prefrontal activation, but multivariate tests revealed that this activity did not carry additional information. The results contradict the hypothesis of a compensatory posterior-to-anterior shift. Instead, they suggest that the increased prefrontal activation reflects reduced efficiency or specificity, rather than compensation.

This research investigated whether episodic memory development can be explained by improvements in relational binding processes, involved in forming novel associations between events and the context in which they occurred. Memory for item-space, item-time, and item-item relations was assessed in an ethnically diverse sample of 151 children aged 7-11 years and 28 young adults. Item-space memory reached adult performance by 9½ years, whereas item-time and item-item memory improved into adulthood. In path analysis, item-space, but not item-time best explained item-item memory. Across age groups, relational binding related to source memory and performance on standardized memory assessments. In conclusion, relational binding development depends on relation type, but relational binding overall supports episodic memory development.

The ability to recognise past events along with the contexts in which they occurred is a hallmark of episodic memory, a critical capacity. Eye movements have been shown to track veridical memory for the associations between events and their contexts (relational binding). Such eye-movement effects emerge several seconds before, or in the absence of, explicit response, and are linked to the integrity and function of the hippocampus. Drawing from research from infancy through late childhood, and by comparing to investigations from typical adults, patient populations, and animal models, it seems increasingly clear that eye movements reflect item-item, item-temporal, and item-spatial associations in developmental populations. We analyse this line of work, identify missing pieces in the literature and outline future avenues of research, in order to help elucidate the development of episodic memory.

Temporal memory in 7-year-olds, 10-year-olds, and young adults (N = 78) was examined introducing a novel eye-movement paradigm. Participants learned object sequences and were tested under three conditions: temporal order, temporal context, and recognition. Age-related improvements in accuracy were found across conditions; accuracy in the temporal conditions was correlated with conventional time knowledge. Eye movements tracked the veridicality of temporal order memory in adults and 10-year-olds seconds before providing memory judgments, suggesting that these movements reflect implicit access to temporal information. Seven-year-olds overall did not show this eye-movement effect, but those who did were more accurate than those who did not. Results suggest that eye movements capture aspects of temporal memory development that precede overt decision processes-with implications for hippocampal development.