Models of cognition and constraints from neuroscience: A case study involving consolidation

A contextual binding theory of episodic memory: systems consolidation reconsidered

Episodic memory reflects the ability to recollect the temporal and spatial context of past experiences. Episodic memories depend on the hippocampus but have been proposed to undergo rapid forgetting unless consolidated during offline periods such as sleep to neocortical areas for long-term storage. Here, we propose an alternative to this standard systems consolidation theory (SSCT) - a contextual binding account - in which the hippocampus binds item-related and context-related information. We compare these accounts in light of behavioural, lesion, neuroimaging and sleep studies of episodic memory and contend that forgetting is largely due to contextual interference, episodic memory remains dependent on the hippocampus across time, contextual drift produces post-encoding activity and sleep benefits memory by reducing contextual interference.

Dissociating visuo-spatial and verbal working memory: It's all in the features

Echoing many of the themes of the seminal work of Atkinson and Shiffrin (The Psychology of Learning and Motivation, 2; 89-195, 1968), this paper uses the feature model (Nairne, Memory & Cognition, 16, 343-352, 1988; Nairne, Memory & Cognition, 18; 251-269, 1990; Neath & Nairne, Psychonomic Bulletin & Review, 2; 429-441, 1995) to account for performance in working-memory tasks. The Brooks verbal and visuo-spatial matrix tasks were performed alone, with articulatory suppression, or with a spatial suppression task; the results produced the expected dissociation. We used approximate Bayesian computation techniques to fit the feature model to the data and showed that the similarity-based interference process implemented in the model accounted for the data patterns well. We then fit the model to data from Guérard and Tremblay (2008, Journal of Experimental Psychology: Learning, Memory, and Cognition, 34, 556-569); the latter study produced a double dissociation while calling upon more typical order reconstruction tasks. Again, the model performed well. The findings show that a double dissociation can be modelled without appealing to separate systems for verbal and visuo-spatial processing. The latter findings are significant as the feature model had not been used to model this type of dissociation before; importantly, this is also the first time the model is quantitatively fit to data. For the demonstration provided here, modularity was unnecessary if two assumptions were made: (1) the main difference between spatial and verbal working-memory tasks is the features that are encoded; (2) secondary tasks selectively interfere with primary tasks to the extent that both tasks involve similar features. It is argued that a feature-based view is more parsimonious (see Morey, 2018, Psychological Bulletin, 144, 849-883) and offers flexibility in accounting for multiple benchmark effects in the field.

Brief period of post-encoding wakeful rest supports verbal memory retention in children aged 10–13 years

Evidence exists that a brief period of wakeful rest after learning can support the retention of memories, whereas a period filled with a cognitive task after learning can weaken the retention of memories. The present study in 10–13 year old children investigated whether wakeful resting after encoding is more beneficial for the retention of new verbal information than watching movies, which reflects a common everyday life/learning break activity in children at this age. Children encoded a word list. After immediate recall of this word list, they wakefully rested for 12 min. Next, children encoded another word list. After immediate recall of this word list, they watched animated short movies for 12 min. The order of the delay conditions (rest, movies) was counterbalanced across children. At the end of the experimental session, a surprise free recall test took place. Overall analyses revealed that while memory performance decreased over time in both the resting condition and movies condition, it decreased significantly more in the movies condition. These results indicate that wakeful resting supports the retention of verbal information in children aged 10–13 years.

Memory Without Consolidation: Temporal Distinctiveness Explains Retroactive Interference

Is consolidation needed to account for retroactive interference in free recall? Interfering mental activity during the retention interval of a memory task impairs performance, in particular if the interference occurs in temporal proximity to the encoding of the to-be-remembered (TBR) information. There are at least two rival theoretical accounts of this temporal gradient of retroactive interference. The cognitive neuroscience literature has suggested neural consolidation is a pivotal factor determining item recall. According to this account, interfering activity interrupts consolidation processes that would otherwise stabilize the memory representations of TBR items post-encoding. Temporal distinctiveness theory, by contrast, proposes that the retrievability of items depends on their isolation in psychological time. According to this theory, information processed after the encoding of TBR material will reduce the temporal distinctiveness of the TBR information. To test between these accounts, implementations of consolidation were added to the SIMPLE model of memory and learning. We report data from two experiments utilizing a two-list free recall paradigm. Modeling results imply that SIMPLE was able to model the data and did not benefit from the addition of consolidation. It is concluded that the temporal gradient of retroactive interference cannot be taken as evidence for memory consolidation.

Refreshing memory traces: thinking of an item improves retrieval from visual working memory

This article provides evidence that refreshing, a hypothetical attention-based process operating in working memory (WM), improves the accessibility of visual representations for recall. "Thinking of", one of several concurrently active representations, is assumed to refresh its trace in WM, protecting the representation from being forgotten. The link between refreshing and WM performance, however, has only been tenuously supported by empirical evidence. Here, we controlled which and how often individual items were refreshed in a color reconstruction task by presenting cues prompting participants to think of specific WM items during the retention interval. We show that the frequency with which an item is refreshed improves recall of this item from visual WM. Our study establishes a role of refreshing in recall from visual WM and provides a new method for studying the impact of refreshing on the amount of information we can keep accessible for ongoing cognition.

Effects of prestudy and poststudy rest on memory: Support for temporal interference accounts of forgetting

According to interference-based theories of memory, including temporal-distinctiveness theory, both prestudy and poststudy rest should have beneficial impacts on memory performance. Specifically, higher temporal isolation of a memorandum should reduce proactive and/or retroactive interference, and thus should result in better recall. In the present study, we investigated the effects of prestudy and poststudy rest in a free recall paradigm. Participants studied three lists of words, separated by either a short or a long period of low mental activity (a tone-detection task). Recall targeted the second list; this list was studied in one of four conditions, defined by the fully crossed factors of prestudy and poststudy rest duration. Two experiments revealed a beneficial effect of prestudy rest (and, to a lesser extent, of poststudy rest) on list recall. This result is in line with interference-based theories of memory. By contrast, a beneficial effect of prestudy rest is not predicted by consolidation accounts of memory and forgetting; our results thus require additional assumptions and/or a better specification of the consolidation process and its time course in order to be reconciled with consolidation theory.

Brief wakeful resting boosts new memories over the long term

A brief wakeful rest after new verbal learning enhances memory for several minutes. In the research reported here, we explored the possibility of extending this rest-induced memory enhancement over much longer periods. Participants were presented with two stories; one story was followed by a 10-min period of wakeful resting, and the other was followed by a 10-min period during which participants played a spot-the-difference game. In Experiment 1, wakeful resting led to significant enhancement of memory after a 15- to 30-min period and also after 7 days. In experiment 2, this striking enhancement of memory 7 days after learning was demonstrated even when no retrievals were imposed in the interim. The degree to which people can remember prose after 7 days is significantly affected by the cognitive activity that they engage in shortly after new learning takes place. We propose that wakeful resting after new learning allows new memory traces to be consolidated better and hence to be retained for much longer.