Egocentric-updating during navigation facilitates episodic memory retrieval

Influential models suggest that spatial processing is essential for episodic memory [O’Keefe, J., & Nadel, L. (1978). The hippocampus as a cognitive map. London: Oxford University Press]. However, although several types of spatial relations exist, such as allocentric (i.e. object-to-object relations), egocentric (i.e. static object-to-self relations) or egocentric updated on navigation information (i.e. self-to-environment relations in a dynamic way), usually only allocentric representations are described as potentially subserving episodic memory [Nadel, L., & Moscovitch, M. (1998). Hippocampal contributions to cortical plasticity. Neuropharmacology, 37(4-5), 431-439]. This study proposes to confront the allocentric representation hypothesis with an egocentric updated with self-motion representation hypothesis. In the present study, we explored retrieval performance in relation to these two types of spatial processing levels during learning. Episodic remembering has been assessed through Remember responses in a recall and in a recognition task, combined with a “Remember-Know-Guess” paradigm [Gardiner, J. M. (2001). Episodic memory and autonoetic consciousness: A first-person approach. Philosophical Transactions of the Royal Society B: Biological Sciences, 356(1413), 1351-1361] to assess the autonoetic level of responses. Our results show that retrieval performance was significantly higher when encoding was performed in the egocentric-updated condition. Although egocentric updated with self-motion and allocentric representations are not mutually exclusive, these results suggest that egocentric updating processing facilitates remember responses more than allocentric processing. The results are discussed according to Burgess and colleagues’ model of episodic memory [Burgess, N., Becker, S., King, J. A., & O’Keefe, J. (2001). Memory for events and their spatial context: models and experiments. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 356(1413), 1493-1503].     

Preserved topographical memory following right temporal lobectomy

In an attempt to study remote memory for visuospatial information, geographical knowledge was examined in patient J.N., who had received a radical right temporal lobectomy to remove a large glioblastoma. In postoperative tests J.N. displayed severe deficits in anterograde memory for visuospatial and verbal material, visuoperceptual functions, constructions, attention, and response initiation. Despite her global cognitive deficiencies she performed normally on the WAIS Information Scale and the Fargo Map Test, a measure of geographical knowledge. In contrast, patients known to have severe amnesia exhibited impairments on tests of geographical knowledge that required precise localization of features such as cities. Assuming that J.N.'s performance is typical of patients with extensive damage to the right temporal lobe, the findings suggest that the integrity of the right temporal lobe is not essential for the retrieval of premorbidly established visuospatial memories.     

Congruity influences memory and judgments of learning during survival processing

A recent line of research has suggested that memory systems evolved to encode fitness-relevant information more effectively than other types of information—a phenomenon known as the “survival processing effect” (Nairne, Thompson, & Pandeirada Journal of Experimental Psychology: Learning, Memory, and Cognition 33:263–273, 2007). However, the basis for the effect has been debated. In addition, it is unknown whether or not individuals will adjust their judgments of learning (JOLs) to reflect the survival processing effect. In three experiments, participants rated 16 words for their relevance to a survival scenario and another 16 words for their relevance to a bank robbery scenario. In Experiment 1A (with no JOLs), the survival processing effect emerged; in Experiment 1B (with JOLs), no survival processing effect emerged, but JOLs were higher in the survival condition. In both cases, these findings were confounded by higher relevance ratings in the survival condition. In Experiment 2, relevance was manipulated within each list, and the survival processing effect was eliminated. Instead, both recall and JOL magnitude were related to level of congruity between the words and type of processing. Together, these results provide further evidence for the role of congruity in the survival processing effect and JOLs.     

Route learning with augmented reality navigation aids

Current trends point towards the development and implementation of augmented reality (AR) navigation assistance systems for drivers. Previous research has found augmented reality can benefit driving performance, but the impact of AR on route learning (spatial knowledge acquisition) has received less attention. The current study used simulated driving scenarios to determine how the type of navigation aid device used (i.e., paper map, electronic map, and AR system) affected driving performance and route learning of 62 driving adults. Route learning was examined at landmark, route, and survey levels. The hypotheses tested were that AR would improve driving performance but diminish route learning compared to paper map use; and that AR would outperform electronic map use in both driving performance and route learning. Results indicated that paper map use led to poorer driving performance and greater route learning. However, map recognition may have been a confounding factor in higher level spatial knowledge acquisition with paper map use. Driving performance and route learning were similar for drivers using the electronic map and AR, but some differences suggested that drivers have reduced uncertainty and hesitation while using AR to navigate in unfamiliar areas.     

Does active learning benefit spatial memory during navigation with restricted peripheral field?

Spatial learning of real-world environments is impaired with severely restricted peripheral field of view (FOV). In prior research, the effects of restricted FOV on spatial learning have been studied using passive learning paradigms – learners walk along pre-defined paths and are told the location of targets to be remembered. Our research has shown that mobility demands and environmental complexity may contribute to impaired spatial learning with restricted FOV through attentional mechanisms. Here, we examine the role of active navigation, both in locomotion and in target search. First, we compared effects of active versus passive locomotion (walking with a physical guide versus being pushed in a wheelchair) on a task of pointing to remembered targets in participants with simulated 10° FOV. We found similar performance between active and passive locomotion conditions in both simpler (Experiment 1) and more complex (Experiment 2) spatial learning tasks. Experiment 3 required active search for named targets to remember while navigating, using both a mild and a severe FOV restriction. We observed no difference in pointing accuracy between the two FOV restrictions but an increase in attentional demands with severely restricted FOV. Experiment 4 compared active and passive search with severe FOV restriction, within subjects. We found no difference in pointing accuracy, but observed an increase in cognitive load in active versus passive search. Taken together, in the context of navigating with restricted FOV, neither locomotion method nor level of active search affected spatial learning. However, the greater cognitive demands could have counteracted the potential advantage of the active learning conditions.

     

Information processing during general anesthesia: Evidence for unconscious memory

Memory for words presented during general anesthesia was studied in two experiments. In Experiment 1, surgical patients (n=80) undergoing elective procedures under general anesthesia were presented shortly before and during surgery with words via headphones. At the earliest convenient time after surgery (within 5 h) and 24 h later, memory was tested by asking patients to complete auditorily presented word stems with the first word that came to mind and to leave out words they remembered having heard earlier (exclusion task). Moreover, patients were requested to perform a “yes/no” forcedchoice recognition task to assess recognition memory for both the pre- and intraoperative words. Memory for the material presented during anesthesia was demonstrated immediately after surgery and 24 h later by means of both tasks. In a second similar experiment (n=80), the results were replicated. These findings show that anesthetized patients can process information that was presented intraoperatively.     

Distinctiveness of processing,processing time and memory performance

The research reported here, explored the conditions where processing time can be used as a predictive measure for retention performance. The results showed that, in similar but quantitatively different tasks, both processing time and retention performance increased with increasing task difficulty. The strongly suggests that processing time can be used as an independent measure for extensiveness of processing, and as a predictor for later retention performance. This relationship, however, is restricted to the comparison of similar processing tasks that differ only in the amount of processing necessary to perform the task.It is hypothesized that longer processing times are indicative of more extensive processing, leading to the formation of more distinctive memory representations. These, in turn, cause higher retention performance because they allow better discrimination from other memory traces, and because they are retrieved more easily.Although distinctiveness of memory representations is an important variable in determining retention performance, it is not the only one. In a recall test, semantic relations between items had an effect on performance independent of distinctiveness.     

Retrieval processing and episodic memory

The emergence of brain imaging has had a major impact on research into the cognitive and neural bases of human memory. An area in which this impact has been particularly strong is retrieval processing - the processes engaged when attempting to retrieve information during a memory test. Several different classes of retrieval process - such as 'mode', 'effort' and 'success' - have been invoked to account for findings from neuroimaging studies of episodic retrieval. In this article we discuss how these different kinds of process, along with a fourth kind associated with 'retrieval orientation', can be investigated in brain imaging experiments. We then review studies of retrieval processing, and assess how well their designs match up to our proposed criteria for dissociating the neural correlates of different classes of retrieval process. We conclude that few studies have used designs that permit these different kinds of process to be independently identified, and that presently there is little evidence to indicate which kinds of processing can be fractionated in terms of their neural correlates.     

Depth of processing and memory organization

Summary The study examined the idea that the organization of information in memory varies depending on the depth of processing during input, as well as on the conditions for retrieval. Two types of memory organization are distinguished: Conceptual organization implies a hierarchical structure in which items are grouped according to a principled taxonomic system (e.g., cow — horse). Associative organization, in contrast, is based on direct links among the members of a group (e.g., cow — milk). Two experiments examined the propositions that conceptual relations require more effort to be encoded during learning and more effort to be utilized during remenbering than associative relations. In Experiment 1 a list of 28 words was used, which could be grouped into 14 conceptual categories or, alternatively, into 14 associative categories of two words each. The words were presented under either shallow or deep encoding conditions. Increased depth of encoding resulted in increased conceptual clustering but had little effect on amount of associative clustering. Similar amounts of associative and conceptual clustering were observed during early output positions, but conceptual clustering tended to increase with recall trials, suggesting that it might depend on the establishment of a retrieval schema. In Experiment 2, after memorizing a list of words, subjects recalled the words either with or without the requirement to perform a secondary task while recalling. Relative to the undisturbed recall condition, the secondary task condition indicated stronger associative than conceptual clustering. The results were seen to support the idea that different types of memory organization may become salient under different attentional conditions.     

Neural representations during sleep: from sensory processing to memory traces

In the course of a day, the brain undergoes large-scale changes in functional modes, from attentive wakefulness to the deepest stage of sleep. The present paper evaluates how these state changes affect the neural bases of sensory and cognitive representations. Are organized neural representations still maintained during sleep? In other words, despite the absence of conscious awareness, do neuronal signals emitted during sleep contain information and have a functional relevance? Through a critical evaluation of the animal and human literature, neural representations at different levels of integration (from the most elementary sensory level to the most cognitive one) are reviewed. Recordings of neuronal activity in animals at presentation of neutral or significant stimuli show that some analysis of the external word remains possible during sleep, allowing recognition of behaviorally relevant stimuli. Event-related brain potentials in humans confirm the preservation of some sensory integration and discriminative capacity. Behavioral and neuroimaging studies in humans substantiate the notion that memory representations are reactivated and are reorganized during post-learning sleep; these reorganisations may account for the beneficial effects of sleep on behavioral performance. Electrophysiological results showing replay of neuronal sequences in animals are presented, and their relevance as neuronal correlates of memory reactivation is discussed. The reviewed literature provides converging evidence that structured neural representations can be activated during sleep. Which reorganizations unique to sleep benefit memory representations, and to what extent the operations still efficient in processing environmental information during sleep are similar to those underlying the non-conscious, automatic processing continually at work in wakefulness, are challenging questions open to investigation.     

Working memory and two-digit number processing

The processing of two-digit numbers in comparison tasks involves the activation and manipulation of magnitude information to decide which number is larger. The present study explored the role of different working memory (WM) components and skills in the processing of two-digit numbers by examining the unit–decade compatibility effect with Arabic digits and number words. In the study, the unit–decade compatibility effect and different WM components were evaluated. The results indicated that the unit–decade compatibility effect was associated to specific WM skills depending on the number format (Arabic digits and number words). We discussed the implications of these results for the decomposed view of two-digit numbers.     

Rote memory and arithmetic fact processing

The goal of the study was to examine the part played by skill in memorizing arbitrary sequences in the efficiency with which normal young adults perform simple arithmetic fact problems. The first experiment showed a clear independent role for sequence memory in all arithmetic fact processing, but a lesser role for semantic retrieval. This result was particularly true for large-answer multiplication problems and subtraction and division problems with large first operands. In a second experiment, which included a visuomotor processing control task, sequence memory predicted processing of all arithmetic problems apart from small additions independently of semantic retrieval, with the most robust independent contribution being to large-answer multiplication problems. The results, which are compatible with Dehaene and colleagues' triple-code model, suggest that rote learning may be a successful way for some people to process arithmetic facts efficiently.     

Working memory and two-digit number processing

The processing of two-digit numbers in comparison tasks involves the activation and manipulation of magnitude information to decide which number is larger. The present study explored the role of different working memory (WM) components and skills in the processing of two-digit numbers by examining the unit-decade compatibility effect with Arabic digits and number words. In the study, the unit-decade compatibility effect and different WM components were evaluated. The results indicated that the unit-decade compatibility effect was associated to specific WM skills depending on the number format (Arabic digits and number words). We discussed the implications of these results for the decomposed view of two-digit numbers.     

Iconic memory and central processing capacity

Three experiments were conducted to assess whether or not iconic memory is influenced by demands placed upon central processing capacity. In Experiment 1 S was required to store material in short-term memory while performing an iconic memory task. In Experiments 2 and 3 S performed an auditory classification task concurrently with iconic storage. The three experiments did not reveal any significant impairment of iconic memory as a function of performing a subsidiary task. Similarly, performance on the subsidiary tasks did not suffer as a result of the concurrent iconic memory task.     

Visuo‐spatial working memory in navigation

Two experiments employed dual task techniques to explore the role of working memory in route learning and subsequent route retrieval. Experiment 1 involved contrasting performance of two groups of volunteers respectively learning a route from a series of map segments or a series of visually presented nonsense words. Both groups performed learning and recognition under articulatory suppression or concurrent spatial tapping. Both concurrent tasks had an overall disruptive effect on each learning task. However, spatial tapping disrupted route recognition rather more than did articulatory suppression, while the nonsense word recognition was impaired more by articulatory suppression than by concurrent spatial tapping. Experiment 2 again used dual task methodology, but explored route learning by asking volunteers to follow the experimenter through the winding streets of a medieval European town centre. Retrieval involved following the same route while the experimenter followed and noted errors in navigation. Overall the results partially replicated those of Experiment 1 in that both concurrent tasks interfered with route learning. However, volunteers with high spatial ability appeared more affected by the concurrent spatial tapping task, whereas low spatial subjects appeared more affected by the concurrent articulatory suppression task. Results are interpreted to suggest that different aspects of working memory are involved in learning a route from a map with a greater emphasis on visuo‐spatial resources, but in tasks set in real environments where many cues of a varied nature are available, only high spatial ability subjects appear to rely heavily upon the visuospatial component of working memory. Copyright © 2002 John Wiley & Sons, Ltd.     

The use of virtual environments for survey spatial ability evaluation in topographical disorientation

Due to their interactivity and to the sense of presence they afford, virtual environments constitute an interesting opportunity to study spatial cognition. In accordance with this perspective, we aimed to introduce a spatial test in virtual simulation in order to investigate the survey spatial ability in patients with topographical disorientation. To do this, we used the "planning in advance task" in a virtual environment that constitutes an effective procedure to experimentally evaluate survey maps. With this procedure we present the single case of a woman, with a right medial temporal lobe lesion, who shows a selective impairment in the acquisition of new spatial relationships. The patient's performance in "planning in advance task" was compared with that of a control group made up of 40 female subjects matched for age and education. Results show how the patient revealed a significantly lower spatial performance when compared to the control group, demonstrating an inability to solve survey-type spatial tasks in complex virtual environments.     

Visuo-spatial processing in working memory

This paper reports four experiments designed to develop a simple technique for the study of visuo-spatial processing within the working memory framework (Baddeley and Hitch, 1974). Experiment 1 involved the matching of successively presented random matrix patterns, as a secondary visual suppression task. This was coupled with rote rehearsal or a visual imagery mnemonic for learning lists of concrete words presented auditorily. Although memory performance with matching dropped overall, the visual mnemonic was differentially affected. Experiment 2 removed the matching decision, with visual presentation of unattended patterns. There was no overall effect of the unattended material, but use of the visual mnemonic was significantly affected. Experiment 3 replicated this result with simpler plain coloured squares as the unattended material.

In Experiment 4, for one group, the unattended material consisted of line drawings of common objects. For a second group, the lists of words for recall were presented visually, with or without unattended speech. The results suggested that unattended pictures disrupt use of a visual mnemonic, while unattended speech disrupts rote rehearsal.

These results suggest that unattended visual material has privileged access to the mechanism(s) involved in short-term visuo-spatial processing and storage. They also suggest that use of a concurrent visual matching task or of unattended visual material may provide tractable techniques for investigating this aspect of cognitive function within the context of working memory.     

Distinctive processing underlies skilled memory

Research on skilled memory has focused on organizational processes to the exclusion of item-specific processes, although theories of skilled memory do acknowledge the importance of both kinds of processes. Using the isolation methodology, we presented lists of American football team names to participants who had either a high or a low level of knowledge about American football. An isolation effect (greater recall of the target in the isolate list than in a homogeneous control list) was observed only with high-knowledge participants. When standard lists were used, an isolation effect was observed with both groups. These findings empirically validate the importance of both organizational and item-specific processing as the basis of distinctive processing underlying skilled memory performance.