Memory For Spatial Location Research Articles

Resuming after Interruption: Exploring the Roles of Spatial and Goal Memory

Interruptions research has generally focused on the factors that make interruptions more or less disruptive to primary task performance, the ways in which people engage the interruption as they disengage from a primary task, and the role of environmental context/cues in primary task resumption. However, little research has focused on investigating the processes by which a person reorients to and resumes the primary task following an interruption. This research explores the potential roles of spatial location and goal memory in the process of resumption. The experiment reported uses a new paradigm in which, following an interruption, a person can be returned to a different task and/or a different location. We found that both goal memory and spatial memory play a role in resuming the primary task following an interruption. However, there is still not a clear picture of how the two interact, and it may be that individual differences play an important role in how people deal with interruptions.

Cue Effects on Memory for Location When Navigating Spatial Displays

Participants maneuvered a rat image through a circular region on the computer screen to find a hidden target platform, blending aspects of two well-known spatial tasks. Like the Morris water maze task, participants first experienced a series of learning trials before having to navigate to the hidden target platform from different locations and orientations. Like the dot-location task, they determined the location of a position within a two-dimensional circular region. This procedure provided a way to examine how the number of surrounding cues (1, 2, or 3) affects the memory for spatial location in navigation. Memory performance was better when there were more cues and when targets were close to cues, consistent with the idea that cues bolster fine-grain memory, especially in proximal regions. Early and late measures of bias in memory reflected biases in a direction toward the nearest cue, implicating a cue-based category structure of the navigational space. Collectively, results suggest cue-based spatial memory representations that have been inferred from the dot-location task generalize to a navigation task within a simple, computer-based environment, as demonstrated by the good fits of the spatial model developed for the dot-location task (Fitting, Wedell, & Allen, 2005, 2007).

Predictors of individual visual memory decline after unilateral anterior temporal lobe resection

Different types of neuropsychological visual memory tasks have been created to quantify deficits associated with right hemisphere dysfunction. There are reports of visual memory impairment after right anterior temporal lobe resection (ATR) compared to left ATR for the processing of faces, abstract designs, and spatial locations, but there are also studies showing no between-group differences. One potential reason for the conflicting results is the use of group mean changes, which mask individual differences. Proportions of individual subjects with decline, no change, or improvement in memory for spatial locations, abstract designs, and unfamiliar faces were evaluated in 83 individuals who underwent a standard ATR (47 right, 36 left) and were left hemisphere language dominant. Type of visual memory ability was an important factor as there were differential individual declines found for memory for spatial locations after right ATR compared to left ATR (27.3% vs 5.9%), but not memory for abstract designs or face memory. Logistic regression indicated that the odds of a spatial memory decline were six times higher for patients who underwent right ATR than left ATR. Memory for spatial locations appears to be particularly vulnerable to decline when a patient undergoes right-anterior temporal lobe resection (ATR) and when the patient has better spatial memory before surgery. Results provide proportions of subjects with significant change to help clinicians and patients make better informed decisions about risks associated with undergoing right ATR.

Trial Outcome and Associative Learning Signals in the Monkey Hippocampus

In tasks of associative learning, animals establish new links between unrelated items by using information about trial outcome to strengthen correct/rewarded associations and modify incorrect/unrewarded ones. To study how hippocampal neurons convey information about reward and trial outcome during new associative learning, we recorded hippocampal neurons as monkeys learned novel object-place associations. A large population of hippocampal neurons (50%) signaled trial outcome by differentiating between correct and error trials during the period after the behavioral response. About half these cells increased their activity following correct trials (correct up cells) while the remaining half fired more following error trials (error up cells). Moreover, correct up cells, but not error up cells, conveyed information about learning by increasing their stimulus-selective response properties with behavioral learning. These findings suggest that information about successful trial outcome conveyed by correct up cells may influence new associative learning through changes in the cell's stimulus-selective response properties.

The processing of spatial information in short-term memory: Insights from eye tracking the path length effect

Serial memory for spatial locations increases as the distance between successive stimuli locations decreases. This effect, known as the path length effect [Parmentier, F. B. R., Elford, G., & Maybery, M. T. (2005). Transitional information in spatial serial memory: Path characteristics affect recall performance. Journal of Experimental Psychology: Learning, Memory & Cognition, 31, 412–427], was investigated in a systematic manner using eye tracking and interference procedures to explore the mechanisms responsible for the processing of spatial information. In Experiment 1, eye movements were monitored during a spatial serial recall task – in which the participants have to remember the location of spatially and temporally separated dots on the screen. In the experimental conditions, eye movements were suppressed by requiring participants to incessantly move their eyes between irrelevant locations. Ocular suppression abolished the path length effect whether eye movements were prevented during item presentation or during a 7s retention interval. In Experiment 2, articulatory suppression was combined with a spatial serial recall task. Although articulatory suppression impaired performance, it did not alter the path length effect. Our results suggest that rehearsal plays a key role in serial memory for spatial information, though the effect of path length seems to involve other processes located at encoding, such as the time spent fixating each location and perceptual organization.

Spatial memory recall in the giant panda (Ailuropoda melanoleuca).

The current study tested spatial memory recall in 1 male and 1 female giant panda (Ailuropoda melanoleuca). The task required subjects to make a delayed response to a previously lighted location, with varying lengths of delay between the observation phase and the test phase. The male subject reached criterion at 2-, 3-, 4-, 5-, 6-, and 10-s delays. The female subject reached criterion at 2-, 3-, 4-, 5-, 6-, 10-, and 15-s delays. The results support the hypothesis that giant pandas demonstrate significant working memory for spatial location in the absence of external cues, which may be an important mechanism for survival in the wild.

Redirected walking to explore virtual environments

Redirected walking has gained popularity in recent years as a way of enhancing the safety of users immersed in a virtual reality simulation and of extending the amount of space that can be simulated in a virtual environment (VE). Limits imposed by the available physical space and functional tracking area are overcome by inducing immersed users to veer imperceptibly in a way that prevents them from leaving the confines of the tracking space. Redirected walking has been shown to be feasible at levels below noticeable thresholds and to function without increasing the incidence of simulator sickness. The present studies demonstrate that redirected walking can function without negatively impacting memory for spatial locations of landmarks in a VE, despite introducing discrepancies between various spatial senses and distorting the spatial mapping of movement onto the environment. Additionally, the present studies implement what, to our knowledge, is the first generalized redirected walking algorithm that is independent of any task or environment structure, and can adaptively steer users in real time as they engage in spontaneous, unconstrained navigation. The studies also demonstrate that such an algorithm can be implemented successfully in a gymnasium-sized space.

External Cue Effects on Memory for Spatial Location within a Rotated Task Field

Fitting, Wedell and Allen (2007) demonstrated that although memory for location within a small two-dimensional task field is largely independent of cues when orientation is fixed, it is highly dependent on cues when orientation varies by rotating the task field on a majority of trials. Their analysis focused only on 0° rotation trials. The current investigation aimed to understand the spatial estimation process under conditions of actual rotation and thereby analyzed the cue effects for the 30°, 90°, and 160° rotation trials of that experiment. Results indicated strong cue-based angular bias effects, which were modeled as resulting from use of cues as category prototypes. Unique to rotation trials, the number of inferred protypes did not generally correspond to the number of cues. In the one-cue condition, there was evidence that an additional prototype was generated at a location opposite the single cue, representing a “phantom” prototype. In the three-cues condition, there was evidence that only two cues served as prototypes biasing estimation. Absolute error in spatial memory was also strongly reduced as a function of proximity to cues, implicating the role of cues in anchoring fine-grain memory. In contrast to the bias measure, effects on absolute error were more directly tied to actual cue locations.

Differential effects of age on item and associative measures of memory: A meta-analysis.

In this meta-analysis, the authors evaluated recent suggestions that older adults' episodic memory impairments are partially due to a reduced ability to encode and retrieve associated/bound units of information. Results of 90 studies of episodic memory for both item and associative information in 3,197 young and 3,192 older adults provided support for the age-related associative/binding deficit suggestion, indicating a larger effect of age on memory for associative information than for item information. Moderators assessed included the type of associations, encoding instructions, materials, and test format. Results indicated an age-related associative deficit in memory for source, context, temporal order, spatial location, and item pairings, in both verbal and nonverbal material. An age-related associative deficit was quite pronounced under intentional learning instructions but was not clearly evident under incidental learning instructions. Finally, test format was also found to moderate the associative deficit, with older adults showing an associative/binding deficit when item memory was evaluated via recognition tests but not when item memory was evaluated via recall tests, in which case the age-related deficits were similar for item and associative information.

The Hippocampus is Preferentially Associated with Memory for Spatial Context

The existence of a functional-anatomic dissociation for retrieving item versus contextual information within subregions of the medial temporal lobe (MTL) is currently under debate. We used a spatial source memory paradigm during event-related functional magnetic resonance imaging to investigate this issue. At study, abstract shapes were presented to the left or right of fixation. During test, old and new shapes were presented at fixation. Participants responded whether each shape had been previously presented on the “left,” the “right,” or was “new.” Activity associated with contextual memory (i.e., source memory) was isolated by contrasting accurate versus inaccurate memory for spatial location. Item-memory-related activity was isolated by contrasting accurate item recognition without contextual memory with forgotten items. Source memory was associated with activity in the hippocampus and parahippocampal cortex. Although item memory was not associated with unique MTL activity at our original threshold, a region-of-interest (ROI) analysis revealed item-memory-related activity in the perirhinal cortex. Furthermore, a functional-anatomic dissociation within the parietal cortex for retrieving item and contextual information was not found in any of three ROIs. These results support the hypothesis that specific subregions in the MTL are associated with item memory and memory for context.

The Hippocampus is Preferentially Associated with Memory for Spatial Context

Abstract The existence of a functional-anatomic dissociation for retrieving item versus contextual information within subregions of the medial temporal lobe (MTL) is currently under debate. We used a spatial source memory paradigm during event-related functional magnetic resonance imaging to investigate this issue. At study, abstract shapes were presented to the left or right of fixation. During test, old and new shapes were presented at fixation. Participants responded whether each shape had been previously presented on the "left," the "right," or was "new." Activity associated with contextual memory (i.e., source memory) was isolated by contrasting accurate versus inaccurate memory for spatial location. Item-memory-related activity was isolated by contrasting accurate item recognition without contextual memory with forgotten items. Source memory was associated with activity in the hippocampus and parahippocampal cortex. Although item memory was not associated with unique MTL activity at our original threshold, a region-of-interest (ROI) analysis revealed item-memory-related activity in the perirhinal cortex. Furthermore, a functional-anatomic dissociation within the parietal cortex for retrieving item and contextual information was not found in any of three ROIs. These results support the hypothesis that specific subregions in the MTL are associated with item memory and memory for context.

Memory for spatial location and object‐place associations are differently processed by the hippocampal formation, parahippocampal areas TH/TF and perirhinal cortex

To clarify the specific contribution of the medial temporal lobe structures in spatial memory, we tested monkeys (Macaca mulatta) with sham operations and with lesions of either the hippocampal formation, areas TH/TF or perirhinal cortex on two versions of the visual-paired comparison task, measuring Spatial Location, and Object-in-Place associations. In the Spatial Location version, the comparison was between two identical objects presented simultaneously in a familiar and a novel location. In the Object-in-Place version, the comparison was between an image consisting of five objects and another image showing the same five objects, but with the position of 2, 3, or 4 of the objects rearranged. Finally, a VPC-Control task was given to animals with hippocampal and perirhinal lesions, in which the comparison was between an image consisting of five objects and another image showing four of the five familiar objects and a new one. Perirhinal lesions yielded no deficit in the Spatial Location task and a deficit in the Object-in-Place task associated with a deficit in the VPC-control task, suggesting that this cortical area does not participate in spatial memory unless the stimuli have overlapping features. Areas TH/TF lesions produced a deficit in both Spatial Location and Object-in-Place tasks, whereas the hippocampal lesions resulted in a deficit of Object-in-Place associations only. The data showed that the hippocampal formation, areas TH/TF, and perirhinal cortex appear to contribute interactively to object and spatial memory processes.

Memory for spatial location: Cue effects as a function of field rotation

We developed theoretical extensions of Huttenlocher, Hedges, and Duncan's (1991) category-adjustment model of human spatial memory to incorporate the use of fuzzy boundariesand cue-determined prototypes. In two experiments, people reproduced locations of dots in a circle, while the number of external reference cues varied. In Experiment 1, the task field was stable and results were consistent with the use of fixed categories unaffected by number of cues. In Experiment 2, the task field was made dynamic by rotation on most trials, with results evaluated for nonrotation trials. The large cue effects observed for angular bias were consistent with the proposed cue-based fuzzy-boundary model. Large cue effects were also observed for absolute error, consistent with a model in which proximity to cues predicts stability of memory. Results point to the key role of orientation to the task environment in determining whether categorical encoding is based on cues.

Behavioural evidence for separating components within visuo-spatial working memory

Several different sources of evidence support the idea that visuo-spatial working memory can be segregated into separate cognitive subsystems. However, the nature of these systems remains unclear. Recently we reported data from neurological patients suggesting that information about visual appearance is retained in a different subsystem from information about spatial location. In this paper we report latency data from neurologically intact participants showing an experimental double dissociation between memory for appearance and memory for location. This was achieved by use of a selective dual task interference technique. This pattern provides evidence supporting the segregation of visuo-spatial memory between two systems, one of which supports memory for stimulus appearance and the other which supports memory for spatial location.

THE PICTURE SUPERIORITY EFFECT IN WORKING MEMORY FOR SPATIAL AND TEMPORAL ORDER

The picture superiority effect in spatial working memory refers to a better retention of the locations of objects or images compared to locations of words. The present research suggests that such effect extends to situations in which the items are serially presented. Participants were required to reproduce different series of icons or words either according to the original spatial configuration, or following the temporal sequence of presentation, or both these aspects together. Overall, both memory for spatial locations and for the temporal order were better with icons than with words. Furthermore, performance decreased when both the features had to be simultaneously retained, suggesting that we do not automatically integrate spatial and temporal information, but such binding requires attentional processing.

Double take: Parallel processing by the cerebral hemispheres reduces attentional blink.

Recent data have shown that parallel processing by the cerebral hemispheres can expand the capacity of visual working memory for spatial locations (J. F. Delvenne, 2005) and attentional tracking (G. A. Alvarez & P. Cavanagh, 2005). Evidence that parallel processing by the cerebral hemispheres can improve item identification has remained elusive. The authors used a novel variant of the attentional blink paradigm to show that the attentional blink is reduced if targets are divided between the hemispheres rather than directed to a single hemisphere. Parallel processing by the cerebral hemispheres can thus expand the capacity of processes involved in item identification. The authors also show that prior engagement of the attentional system may compromise the processing of items directed to the right visual field. This pseudoextinction may explain the failures of previous attempts to demonstrate that parallel processing can improve item identification (J. F. Delvenne, 2005; S. J. Luck, S. A. Hillyard, G. R. Mangun, & M. S. Gazzaniga, 1989).

Rehearsal processes in visuo-spatial working memory

The concept of an active rehearsal mechanism that maintains material within short-term memory has been an integral feature of theoretical modelling in the 30 years since the publication of Baddeley and Hitch’s multi-component model of working memory (Baddeley and Hitch 1974). The majority of research on the topic has focused on the maintenance of verbal material, and a well-documented account of verbal rehearsal has developed in which an active articulatory mechanism revives auditory memory traces stored within a temporary phonological store (Baddeley 1986, 2000). In contrast, accounts of rehearsal processes within visuo-spatial working memory have been less well developed (Pearson 2001, in press). This paper will review recent research that has focused on the rehearsal of visual and spatial material within working memory, with a focus on short-term memory for serially-presented spatial locations. Experiments will be discussed which have investigated the nature of the cognitive mechanisms that underlie performance on specific visuo-spatial working memory tasks, with the emphasis on exploring the extent of central executive involvement (Rudkin et al. in press). Work will also be discussed that has demonstrated a role for oculomotor control processes during the rehearsal of location-specific representations in working memory (Pearson and Sahraie 2003). It will be argued that visuo-spatial rehearsal processes within working memory are clearly more complex than comparable rehearsal processes that may operate for verbal material, and involve modality-specific oculomotor processes, as well as more strategically-based processes more closely associated with the central executive component.

ERP correlates of working memory for sound and picture locations

Previous studies conducted in our lab provided evidence that object locations of sounds and pictures are maintained by a common mechanism. This suggests that working memory for spatial locations is not separated according to input modality. Additionally, it is known that in visual short-term memory, location and object information are maintained by different processes. Taken together, this suggests that the distinction between location and object processing should also be valid for auditory memory. We conducted an ERP slow wave study to investigate to what extend this dissociation holds true for both pictures and sounds. In our experiment, we varied both, modality (sounds vs. pictures) and task type (object vs. location memory). Subjects studied either sounds or pictures presented at different locations. The study phase was followed by a cue which indicated what information to maintain during the retention interval. Subjects either needed to maintain object identity or object location to carry out an old/new decision in the following test. They were instructed to actively maintain the relevant information during the retention interval. ERP slow waves recorded during maintenance differed both by task type and modality, suggesting information-specific processing. We discuss the ERP results with respect to a model of domain-specific processing in a network structured along the anterior–posterior dimension of the brain.

Lesions of the Vestibular System Disrupt Hippocampal Theta Rhythm in the Rat

The hippocampus has a major role in memory for spatial location. Theta is a rhythmic hippocampal EEG oscillation that occurs at approximately 8 Hz during voluntary movement and that may have some role in encoding spatial information. We investigated whether, as part of this process, theta might be influenced by self-movement signals provided by the vestibular system. The effects of bilateral peripheral vestibular lesions, made > or = 60 days prior to recording, were assessed in freely moving rats. Power spectral analysis revealed that theta in the lesioned animals had a lower power and frequency compared with that recorded in the control animals. When the electroencephalography (EEG) was compared in epochs matched for speed of movement and acceleration, theta was less rhythmic in the lesioned group, indicating that the effect was not a result of between-group differences in this behavior. Blood measurements of corticosterone were also similar in the two groups indicating that the results could not be attributed to changes in stress levels. Despite the changes in theta EEG, individual neurons in the CA1 region of lesioned animals continued to fire with a periodicity of approximately 8 Hz. The positive correlation between cell firing rate and movement velocity that is observed in CA1 neurons of normal animals was also maintained in cells recorded from lesion group animals. These findings indicate that although vestibular signals may contribute to theta rhythm generation, velocity-related firing in hippocampal neurons is dependent on nonvestibular signals such as sensory flow, proprioception, or motor efference copy.

Acute dose of MDMA (75 mg) impairs spatial memory for location but leaves contextual processing of visuospatial information unaffected

Research concerning spatial memory in 3,4-methylenedioxymethamphetamine (MDMA) users has presented conflicting results showing either the presence or absence of spatial memory deficits. Two factors may have confounded results in abstinent users: memory task characteristics and polydrug use. The present study aims to assess whether a single dose of MDMA affects spatial memory performance during intoxication and withdrawal phase and whether spatial memory performance after MDMA is task dependent. Eighteen recreational MDMA users participated in a double-blind, placebo-controlled, three-way crossover design. They were treated with placebo, MDMA 75 mg, and methylphenidate 20 mg. Memory tests were conducted between 1.5 and 2 h (intoxication phase) and between 25.5 and 26 h (withdrawal phase) post-dosing. Two spatial memory tasks of varying complexity were used that required either storage of stimulus location alone (spatial memory task) or memory for location as well as processing of content or contextual information (change blindness task). After a single dose of MDMA, the subjects made larger localization errors and responded faster compared to placebo in the simple spatial memory task during intoxication phase. Inaccuracy was not due to increased response speed, as determined by regression analysis. Performance in the change blindness task was not affected by MDMA. Methylphenidate did not affect performance on any of the tasks. It is concluded that a single dose of MDMA impairs spatial memory for location but leaves processing of contextual information intact.