A key question in the management of group-housed captive animals is how long can an individual be removed from a social group and still be reintroduced with minimal social upheaval. In order to answer this question we require a knowledge of how long cage-mates, following a specified period of group-housing, can remember one another after separation. This issue was investigated in laboratory rats (Rattus norvegicus). Rats were group-housed for 18 days before being housed individually. One hour, 48 hr, and 96 hr after separation, they were exposed simultaneously to odour cues originating from unfamiliar rats and from former cage-mates. The rats spent significantly more time investigating the unfamiliar odour 1 hr and 48 hr, but not 96 hr, after separation, suggesting that, after 18 days of group-housing, juvenile rats remember former cage-mates for between 48 and 96 hr. The implications of this result for animal welfare are discussed.

This paper examines conditions that do or do not lead to accurate judgments of frequency (JOF) and judgments of duration (JOD). In three experiments, duration and frequency of visually presented stimuli are varied orthogonally in a within-subjects design. Experiment 1 reveals an asymmetric judgment pattern. JOFs reflected actual presentation frequency quite accurately and were unbiased by exposure duration. Conversely, JODs were almost insensitive to actual exposure duration and were systematically biased by presentation frequency. We show, however, that a tendency towards a symmetric judgment pattern can be obtained by manipulating encoding conditions. Sustaining attention during encoding (Experiment 2) or enhancing richness of the encoded stimuli (Experiment 3) increases judgment sensitivity in JOD and yields biases in both directions (JOF biased by exposure duration, JOD biased by presentation frequency). The implications of these findings for underlying memory mechanisms are discussed.

Objectives: Reading aloud (vocal production) enhances memory relative to reading silently, the Production Effect (PE) in memory. Thus, vocalization has been suggested as a mnemonic device. The current study tested the PE in a sample of adults with ADHD and in a control sample, evaluating verbal learning. Methods: Twenty adults with ADHD and 21 controls learned a list of words, half by reading aloud and half by reading silently. Free recall test followed. The participants with ADHD performed the task twice (in two different sessions in a counterbalanced order), before self-administration of a single dose of methylphenidate (MPH) and 60-min after dosage. Results: PEs were found for all groups. Memory was better for the controls than for the ADHD group (with or without MPH). In the ADHD group, recall rates and the PE were higher with than without MPH. Conclusions: These results suggest that vocalization yields a larger memory gain with MPH. Possibly, MPH enables the ADHD participants to better shift their attention to the aloud words, enhancing their retrieval rates. Theoretically, these findings stress the role of attention in the PE. (JINS, 2019, 25, 230–235)

Despite an increase in bilingualism and the use of English as a medium of instruction, little research has been done on bilingual memory for learnt information. In a previous study, we found an L2 recall cost but equal recognition performance in L2 versus L1 when students studied short expository texts (Vander Beken & Brysbaert, 2017). In this paper, we investigate whether there is a recognition cost after a longer delay, which would indicate that the memory trace is weaker in L2. Results showed equal performance in L1 and L2, suggesting that the recall cost is either located at the production level, or that the levels-of-processing effect is mediated by language, with unaffected surface encoding leading to effective marginal knowledge on the one hand, and hampered deep encoding leading to ineffective (uncued) recall. This paper also contains the Dutch vocabulary test we used for native speakers.

Some individuals with multiple sclerosis (MS) show decrements in long-term memory (LTM) while other individuals do not. The theory of cognitive reserve suggests that individuals with greater pre-morbid intellectual enrichment are protected from disease-related cognitive decline. How intellectual enrichment affords this benefit remains poorly understood. The present study tested an exploratory meditational hypothesis whereby working memory (WM) capacity may mediate the relationship between intellectual enrichment and verbal LTM decline in MS. Intellectual enrichment, verbal LTM, and WM capacity were estimated with the Wechsler Test of Adult Reading and Peabody Picture Vocabulary Test, delayed recall of the Hopkins Verbal Learning Test-Revised and Logical Memory of the Wechsler Memory Scale, and Digit Span Total, respectively. Intellectual enrichment predicted LTM (B=.54; p=.003) and predicted WM capacity (B=.91; p<.001). WM capacity predicted LTM, (B=.44; p<.001) and fully mediated the relationship between intellectual enrichment (B=.24; p=.27) and LTM (B=.33, p=.03), Sobel test, Z=3.31, p<.001. These findings implicate WM capacity as an underlying mechanism of cognitive reserve and are an initial first step in understanding the relationship between intellectual enrichment, WM, and LTM in MS. (JINS, 2014, 20, 1–5)

Autobiographical memory involves the recall of personal facts (semantic memory) and re-experiencing of specific personal events (episodic memory). Although impairments in autobiographical memory have been found in adults with unilateral temporal lobe epilepsy (TLE) and attributed to compromised hippocampal integrity, it is not yet known whether this occurs in children with TLE. In the current study, 21 children with TLE and 24 healthy controls of comparable age, sex, and socioeconomic status were administered the Children's Autobiographical Interview. Compared to controls, children with TLE recalled fewer episodic details, but only when no retrieval prompts were provided. There was no difference between the groups for semantic autobiographic details. Interestingly, the number of episodic details recalled increased significantly from 6 to 16 years of age in healthy control children, but not in children with TLE. Exploratory analyses revealed that, within the group of children with TLE, epilepsy factors, including presence or absence of structural hippocampal abnormalities, did not relate to the richness of episodic recall. Our results provide first evidence of autobiographical episodic memory deficits in children with TLE. (JINS, 2013, 19, 1–12)

This Short Review critically evaluates three hypotheses about the effects of emotion on memory: First, emotion usually enhances memory. Second, when emotion does not enhance memory, this can be understood by the magnitude of physiological arousal elicited, with arousal benefiting memory to a point but then having a detrimental influence. Third, when emotion facilitates the processing of information, this also facilitates the retention of that same information. For each of these hypotheses, we summarize the evidence consistent with it, present counter-evidence suggesting boundary conditions for the effect, and discuss the implications for future research. (JINS, 2013, 19, 1–9)

Whereas patients with Alzheimer's disease (AD) experience difficulties forming and retrieving memories, their memory impairments may also partially reflect an unrecognized dysfunction in sleep-dependent consolidation that normally stabilizes declarative memory storage across cortical areas. Patients with amnestic mild cognitive impairment (aMCI) exhibit circumscribed declarative memory deficits, and many eventually progress to an AD diagnosis. Whether sleep is disrupted in aMCI and whether sleep disruptions contribute to memory impairment is unknown. We measured sleep physiology and memory for two nights and found that aMCI patients had fewer stage-2 spindles than age-matched healthy adults. Furthermore, aMCI patients spent less time in slow-wave sleep and showed lower delta and theta power during sleep compared to controls. Slow-wave and theta activity during sleep appear to reflect important aspects of memory processing, as evening-to-morning change in declarative memory correlated with delta and theta power during intervening sleep in both groups. These results suggest that sleep changes in aMCI patients contribute to memory impairments by interfering with sleep-dependent memory consolidation. (JINS, 2012, 18, 490–500)

Human agents draw a variety of inferences effortlessly, spontaneously, and with remarkable efficiency – as though these inferences were a reflexive response of their cognitive apparatus. Furthermore, these inferences are drawn with reference to a large body of background knowledge. This remarkable human ability seems paradoxical given the complexity of reasoning reported by researchers in artificial intelligence. It also poses a challenge for cognitive science and computational neuroscience: How can a system of simple and slow neuronlike elements represent a large body of systemic knowledge and perform a range of inferences with such speed? We describe a computational model that takes a step toward addressing the cognitive science challenge and resolving the artificial intelligence paradox. We show how a connectionist network can encode millions of facts and rules involving n-ary predicates and variables and perform a class of inferences in a few hundred milliseconds. Efficient reasoning requires the rapid representation and propagation of dynamic bindings. Our model (which we refer to as SHRUTI) achieves this by representing (1) dynamic bindings as the synchronous firing of appropriate nodes, (2) rules as interconnection patterns that direct the propagation of rhythmic activity, and (3) long-term facts as temporal pattern-matching subnetworks. The model is consistent with recent neurophysiological evidence that synchronous activity occurs in the brain and may play a representational role in neural information processing. The model also makes specific psychologically significant predictions about the nature of reflexive reasoning. It identifies constraints on the form of rules that may participate in such reasoning and relates the capacity of the working memory underlying reflexive reasoning to biological parameters such as the lowest frequency at which nodes can sustain synchronous oscillations and the coarseness of synchronization.