Search

Preschoolers' repeating patterning knowledge is predictive of their concurrent and later math and numeracy knowledge, but strong experimental evidence is needed to determine if these relations are causal. The purpose of the current study was to examine the causal effects of repeating patterning and numeracy tutoring on repeating patterning, numeracy, and general mathematics knowledge in the year before kindergarten (i.e., pre-K). Children in pre-K (N = 211) were randomly assigned to receive five sessions of researcher-delivered tutoring (a) on repeating patterns and numeracy or (b) on numeracy (and literacy as an active control), or received no tutoring and business as usual classroom instruction (control). Children who received tutoring in repeating patterning and numeracy improved in their repeating patterning knowledge the most. However, children's general math and numeracy knowledge improved similarly across conditions, and a specific aspect of numeracy emphasized during the tutoring did not improve. Children's repeating patterning knowledge is malleable, but this initial attempt to demonstrate causal links between repeating patterning and math knowledge was not successful. Results parallel mixed success in research training other skills, such as working memory or spatial skills, for improving mathematics knowledge. Findings are discussed in terms of the relations between patterning, numeracy, and general math knowledge in preschoolers. Educational Impact and Implications Statement: We know that preschool children with better repeating patterning knowledge (i.e., understanding predictable sequences with a part that repeats, like objects arranged ABABAB) also tend to do better on math and numeracy tasks. How can we improve preschool children's patterning knowledge, and does teaching preschoolers patterning along with numbers improve their math knowledge? Our five tutoring sessions improved children's patterning knowledge, but did not improve their math knowledge. The patterning instruction was designed to improve children's knowledge of and ability to duplicate, extend, and abstract (i.e., duplication with different materials) repeating patterns, and identify the unit of repeat in those patterns. Although it was not designed to be used for classroom instruction, key features of our tutoring protocol can be incorporated into preschool teachers' patterning instruction. [ABSTRACT FROM AUTHOR]

Real-world scenes elicit anticipatory representation in long-term memory (LTM) and working memory (WM) resulting in boundary extension (BE). Would the same results hold for nonscene patterns of objects? In Experiment 1A (LTM-paradigm), 15 regular or 15 random object-patterns were sequentially presented (10 s each); a boundary-rating-task followed. Both pattern-types elicited BE. Surprisingly, regularity (greater pattern predictability) did not enhance BE. Instead, random patterns more consistently yielded BE. Perhaps random object-groupings enhance BE (e.g., more scene-like). Objects within regular patterns were colored to create object-groupings; this increased BE compared to regular patterns without color groups, but only in 1 of the 2 tests (Experiment 1B, LTM-paradigm). In Experiment 2 (WM-paradigm), a briefly presented pattern, regular or random, was followed by a 2-s masked interval and a boundary-rating-task on each trial. Here, results reversed: patterns now elicited boundary restriction (whether or not a concurrent task had been presented to prevent verbalization). Under time pressure, without real-world layout and meaning, pattern elements may not have cohered into a unified expanse, failing to elicit BE and resulting in loss of peripheral content. We propose 2 classes of visual content that may determine anticipatory representation: content that embellishes space versus content that defines space. Public Significance Statement: When viewing real-world scenes, the brain anticipates surrounding layout; this study showed that novel patterns also elicited anticipatory representation given sufficient time, but not when the same patterns were briefly presented. Not only was anticipatory processing halted, but also participants lost memory for the peripheral elements of the patterns. This demonstrates the critical role of top-down knowledge and expectations in supporting anticipatory representation, which may be crucial for a moving observer's successful interaction with the surrounding world. [ABSTRACT FROM AUTHOR]

Objects learned within single enclosed spaces (e.g., rooms) can be represented within a single reference frame. Contrarily, the representation of navigable spaces (multiple interconnected enclosed spaces) is less well understood. In this study we examined different levels of integration within memory (local, regional, global), when learning object locations in navigable space. Participants consecutively learned two distinctive regions of a virtual environment that eventually converged at a common transition point and subsequently solved a pointing task. In Experiment 1 pointing latency increased with increasing corridor distance to the target and additionally when pointing into the other region. Further, when pointing within a region alignment with local and regional reference frames, when pointing across regional boundaries alignment with a global reference frame was found to accelerate pointing. Thus, participants memorized local corridors, clustered corridors into regions, and integrated globally across the entire environment. Introducing the transition point at the beginning of learning each region in Experiment 2 caused previous region effects to vanish. Our findings emphasize the importance of locally confined spaces for structuring spatial memory and suggest that the opportunity to integrate novel into existing spatial information early during learning may influence unit formation on the regional level. Further, global representations seem to be consulted only when accessing spatial information beyond regional borders. Our results are inconsistent with conceptions of spatial memory for large scale environments based either exclusively on local reference frames or upon a single reference frame encompassing the whole environment, but rather support hierarchical representation of space. [ABSTRACT FROM AUTHOR]

The dominant paradigm for understanding working memory, or the combination of the perceptual, attentional, and mnemonic processes needed for thinking, subdivides short-term memory (STM) according to whether memoranda are encoded in aural-verbal or visual formats. This traditional dissociation has been supported by examples of neuropsychological patients who seem to selectively lack STM for either aural-verbal, visual, or spatial memoranda, and by experimental research using dual-task methods. Though this evidence is the foundation of assumptions of modular STM systems, the case it makes for a specialized visual STM system is surprisingly weak. I identify the key evidence supporting a distinct verbal STM system-patients with apparent selective damage to verbal STM and the resilience of verbal short-term memories to general dual-task interference-and apply these benchmarks to neuropsychological and experimental investigations of visual-spatial STM. Contrary to the evidence on verbal STM, patients with apparent visual or spatial STM deficits tend to experience a wide range of additional deficits, making it difficult to conclude that a distinct short-term store was damaged. Consistently with this, a meta-analysis of dual-task visual-spatial STM research shows that robust dual-task costs are consistently observed regardless of the domain or sensory code of the secondary task. Together, this evidence suggests that positing a specialized visual STM system is not necessary. [ABSTRACT FROM AUTHOR]

The present study investigated whether older adults' visuospatial working memory shows effects of environmental support for rehearsal similar to those observed in young adults (Lilienthal, Hale, & Myerson, 2014). When the duration of interitem intervals was 4 s and participants had sufficient time to rehearse, location memory spans were larger in both age groups when environmental support was present than when support was absent. Critically, however, the age-related difference in memory was actually larger when support was provided, suggesting that young and older adults may differ in their rehearsal of to-be-remembered locations. (PsycINFO Database Record [ABSTRACT FROM AUTHOR]

The head direction system is composed of neurons found in a number of connected brain areas that fire in a sharply tuned, directional way. The function of this system, however, has not been fully established. To assess this, we devised a novel spatial landmark task, comparable to the paradigms in which stimulus control has been assessed for spatially tuned neurons. The task took place in a large cylinder and required rats to dig in a specific sand cup, from among 16 alternatives, to obtain a food reward. The reinforced cup was in a fixed location relative to a salient landmark, and probe sessions confirmed that the landmark exerted stimulus control over the rats' cup choices. To assess the contribution of the head direction cell system to this memory task, half of the animals received ibotenic acid infusions into the lateral mammillary nuclei (LMN), an essential node in the head direction network, while the other received sham lesions. No differences were observed in performance of this task between the 2 groups. Animals with LMN lesions were impaired, however, in reversal learning on a water maze task. These results suggest that the LMN, and potentially the head direction cell system, are not essential for the use of visual landmarks to guide spatial behavior. [ABSTRACT FROM AUTHOR]

Cognitive impairment is a prominent feature in a range of different movement disorders. Children with Alternating Hemiplegia of Childhood are prone to developmental delay, with deficits in cognitive functioning becoming progressively more evident as they grow older. Heterozygous mutations of the ATP1A3 gene, encoding the Na+, K+-ATPase α3 subunit, have been identified as the primary cause of Alternating Hemiplegia. Heterozygous Myshkin mice have an amino acid change (I810N) in Na+, K+-ATPase α3 that is also found in Alternating Hemiplegia. To investigate whether Myshkin mice exhibit learning and memory deficits resembling the cognitive impairments of patients with Alternating Hemiplegia, we subjected them to a range of behavioral tests that interrogate various cognitive domains. Myshkin mice showed impairments in spatial memory, spatial habituation, locomotor habituation, object recognition, social recognition, and trace fear conditioning, as well as in the visible platform version of the Morris water maze. Increasing the duration of training ameliorated the deficit in social recognition but not in spatial habituation. The deficits of Myshkin mice in all of the learning and memory tests used are consistent with the cognitive impairment of the vast majority of AHC patients. These mice could thus help advance our understanding of the underlying neural mechanisms influencing cognitive impairment in patients with ATVMJ-related disorders. [ABSTRACT FROM AUTHOR]

Posttraining intracranial self-stimulation (SS) in the lateral hypothalamus facilitates the acquisition and retention of several implicit and explicit memory tasks. Here, intracellular injections of Lucifer yellow were used to assess morphological changes in hippocampal neurons that might be specifically related to the facilitative posttraining SS effect upon the acquisition and retention of a distributed spatial task in the Morris water maze. We examined the structure, size and branching complexity of cornus ammonis 1 (CA1) cells, and the spine density of CA1 pyramidal neurons and granular cells of the dentate gyrus (DG). Animals that received SS after each acquisition session performed faster and better than Sham ones--an improvement that was also evident in a probe trial 3 days after the last training session. The neuromorphological analysis revealed an increment in the size and branching complexity in apical CA 1 dendritic arborization in SS-treated subjects as compared with Sham animals. Furthermore, increased spine density was observed in the CA1 field in SS animals, whereas no effects were observed in DG cells. Our results support the hypothesis that the facilitating effect of SS on the acquisition and retention of a spatial memory task could be related to structural plasticity in CA1 hippocampal cells. [ABSTRACT FROM AUTHOR]

Studies of the testing effect have shown that retrieval significantly improves learning. However, most of these studies have been restricted to simple types of declarative verbal knowledge. Five experiments were designed to explore whether testing improves acquisition of route knowledge, which has a procedural component consisting of actions to be performed at decision points (Golledge, 1991). Participants learned a route through a series of connected rooms in a virtual building. Each room contained multiple doors, only one of which led to the next room. During encoding, participants were shown the correct sequence of doors in a manner similar to global positioning system (GPS) navigation guidance. During subsequent exposures to the route, participants were either shown the correct sequence again or had to recall the sequence from memory. Participants later completed a final test in which they traversed the route without guidance or feedback. Testing improved route memory compared to studying, but only when participants were given feedback about the correct door prior to moving through the room. When feedback occurred after moving to an incorrect door, testing resulted in worse performance compared to studying. These findings parallel work on errorless learning, in which procedural skills are acquired more quickly when errors are minimized during learning. [ABSTRACT FROM AUTHOR]

We investigated the role of the septo-hippocampal cholinergic projection in anxiety, spatial novelty preference, and differential reward for low rates of responding (DRL) performance. Cholinergic neurons of the rat medial septum (MS) and the vertical limb of the diagonal band of Broca (VDB) were lesioned using the selective immunotoxin, 192 IgG-saporin. Rats were then tested on several behavioral tests previously shown to be sensitive to either (a) hippocampal lesions or (b) nonselective MS/VDB lesions which target both cholinergic and y-aminobutyric acid (GABA)-ergic projections, or both. Saporin lesions substantially reduced hippocampal cholinergic innervation, resulting in an absence of acetyl cholinesterase staining and markedly reduced choline acetyltransferase activity (mean reduction: 80 ± 5%; range: 50-97%). However, the saporin-lesioned rats did not differ from control rats in any of the behavioral tests. Thus we found no evidence from these lesion studies that the septo-hippocampal cholinergic projection plays an essential role in anxiety, spatial novelty preference, or DRL. [ABSTRACT FROM AUTHOR]

When participants are presented with a short list of unrelated words and they are instructed that they may recall in any order, they nevertheless show a very strong tendency to recall in forward serial order. Thus, if asked to recall in any order, "hat, mouse, tea, stairs," participants often respond "hat, mouse, tea, stairs" even though there was no forward order requirement of the task. In 4 experiments, we examined whether this tendency is language-specific, reflecting mechanisms involved with speech perception, speech production, and/or verbal short-term memory. Specifically, we examined whether we would observe similar findings when participants were asked to recall, in any order, lists of between 1 and 15 nonverbal stimuli, such as visuospatial locations (Experiment 1, Experiment 3, Experiment 4), or touched facial locations (Experiment 2). Contrary to a language-specific explanation, we found corresponding tendencies (albeit somewhat reduced) in the immediate free recall of these nonverbal stimuli. We conclude that the tendency to initiate recall of a short sequence of items with the first item is a general property of memory, which may be augmented by verbal coding. [ABSTRACT FROM AUTHOR]

The ability to navigate without getting lost is an important aspect of quality of life. In 5 studies, we evaluated how spatial learning is affected by the increased demands of keeping oneself safe while walking with degraded vision (mobility monitoring). We proposed that safe low vision mobility requires attentional resources, providing competition for those needed to learn a new environment. In Experiments 1 and 2, participants navigated along paths in a real-world indoor environment with simulated degraded vision or normal vision. Memory for object locations seen along the paths was better with normal compared with degraded vision. With degraded vision, memory was better when participants were guided by an experimenter (low monitoring demands) versus unguided (high monitoring demands). In Experiments 3 and 4, participants walked while performing an auditory task. Auditory task performance was superior with nonnal compared with degraded vision. With degraded vision, auditory task performance was better when guided compared with unguided. In Experiment 5, participants performed both the spatial learning and auditory tasks under degraded vision. Results showed that attention mediates the relationship between mobility-monitoring demands and spatial learning. These studies suggest that more attention is required and spatial learning is impaired when navigating with degraded viewing. [ABSTRACT FROM AUTHOR]

Researchers in spatial cognition have debated for decades the specificity of the mechanisms through which spatial information is processed and stored. Interestingly, although rodents are the preferred animal model for studying spatial navigation, the behavioral methods traditionally used to assess spatial memory do not effectively test the predictions of specificity in their representation. To address such issues, the present study tested the ability of mice to use boundary geometry and features to remember a goal location across 2 types of tasks--a working memory task with a changing goal location, and a reference memory task with 1 rewarded goal location. We show for the first time that mice, like other animals, can successfully encode boundary geometry in a working memory spatial mapping task, just as they do in a reference memory task. Their use of a nongeometric featural cue (striped pattern), in contrast, was more limited in the working memory task, although it quickly improved in the reference memory task. We discuss the implications of these findings for future research on the neural and genetic underpinnings of spatial representations. [ABSTRACT FROM AUTHOR]

Studies of the effects of aging on decision making suggest that choices can be altered in a variety of ways depending on the situation, the nature of the outcome and risk, or certainty levels. To better characterize how aging impacts decision making in rodents, young and aged Fischer 344 rats underwent a series of probabilistic discounting tasks in which reward magnitude and probabilities were manipulated. Young rats tended to choose 1 of 2 different strategies: (a) to press for the large/uncertain reward, regardless of the reward probability; or (b) to continually adapt their behavior according to the odds of winning. The first strategy was adopted by about half of the younger rats, the second by the remaining young animals and the entire group of aged rats. Additionally, we found that when the odds of winning were varied from uncertain to certain during a session, aged rats chose most often the lever associated with the small/ certain reward. This is consistent with an interpretation of increased risk aversion. When this behavior was further characterized using a lose-shift analysis, it appears that older rats exhibited an increased sensitivity to negative feedback. In contrast, sensitivity to wins was unaltered in aged rats compared with young, suggesting that aging selectively impacts rat's behavior following losses. In line with some human aging studies, it appears that aged rats are either more risk averse or have a greater certainty bias, which may result from age differences in emotion regulation. [ABSTRACT FROM AUTHOR]

The consequences of traumatic brain injury (TBI) sustained during late adolescence (7 weeks old) on spontaneous object recognition memory and on anxiety-like behaviors in the elevated plus maze were tested in rats during adulthood. Testing took place at 2 different postinjury times, in separate groups: 3 and 6 weeks, when animals were 10 and 13 weeks old, respectively. The rats were either submitted to controlled cortical impact injury, an experimental model of focal TBI with contusion, or were shamoperated. TBI animals failed to remember the familiar object and had a significantly lower performance than sham-operated animals, indicating memory disruption, when the retention delay was 24 hr, but not when it was 3 hr. TBI did not have any significant effect on the main anxiety-related behaviors, but it reduced time in the central platform of the elevated plus maze. The effects of TBI on memory and on anxiety-like behaviors were similar at the 2 postinjury times. In both TBI and sham-operated groups, animals tested 6 weeks after surgery had lower anxiety-related indices than those tested at 3 weeks, an effect that might be indicative of reduced anxiety levels with increasing age. In summary, focal TBI with contusion sustained during late adolescence led to object recognition memory deficits in a 24-hr test during adulthood but did not have a major impact on anxiety-like behaviors. Memory deficits persisted for at least 6 weeks after injury, indicating that spontaneous modifications of these functional disturbances did not take place along this time span. [ABSTRACT FROM AUTHOR]

The Simon effect refers to the relatively poorer response times and accuracy when responding to targets that appear in a task-irrelevant spatial location that is incongruent with the location of the correct response key, compared with targets that appear in spatially congruent locations. Like Stroop and flanker effects, the Simon effect is thought to result from conflict between an irrelevant response tendency and an intended response. Because attentional control has been linked to conflict resolution, the Simon task has been proffered as a possible tool for measuring the efficacy of executive control mechanisms. These mechanisms are also involved in working memory (WM) processes, and are thought to be responsible for maintaining information in the presence of continued processing or distraction. The present study investigated the interface between WM and attention by examining the time course of the Simon effect over the response time distributions under varying WM load conditions. Participants completed verbal 0-back, spatial 0-back, verbal 2-back, and spatial 2-back tasks. Results show that the Simon effect is diminished in high WM load tasks compared with low-load tasks, and that the Simon effect interacts with the spatial task domain such that the effect persists across the distribution of response times. In contrast, the Simon effect peaks and decays in verbal tasks. The results demonstrate that the Simon effect interacts with WM load and task domain. The results suggest that the effect is more modifiable than expected, and support a complex interface between WM and attentional control. [ABSTRACT FROM AUTHOR]

A spatial task was used to investigate if a stimulus could set the occasion for responding to a landmark. Pigeons were trained with a positive occasion setter (OS: a colored background display) signaling the contingency between a landmark (LM; visual patterned stimulus) and the location of a rewarded response. The two most common tests of an OS (transfer tests and post-training extinction of the OS) were then conducted. In Experiment 1, two occasion setting pairs were trained (+←XA/YB→+/A--/B --) with unique spatial relationships to a reinforced goal location. Transfer tests (X B - and YA --) revealed more responding to a landmark when paired with the same OS from training (e.g., XA) than on transfer tests, which was greater still than landmark-only trials (A -). Three pigeons demonstrated good spatial control of responding by the LM on transfer tests. In Experiment 2, the contingency and spatial relationship (e.g., left or right) between LM A and the goal were signaled by the OS (+⁤XA/YA #8594;+/+ ←ZB/C→+/A-/B-). LM C was trained without an OS to assess the role of training history during transfer. Transfer tests again indicated an OS could facilitate responding and the LM controlled the location of responding. Training history affected spatial control, but not facilitation, by LM C. Lastly, post-training extinction of X had no effect on facilitation or spatial control during subsequent XA trials. These experiments are the first to evaluate conditional control of spatial information by landmarks using both of the standard tests for occasion setting. [ABSTRACT FROM AUTHOR]

Pigeons' performance on a working memory task, symbolic delayed matching-to-sample, was used to examine the interaction between working memory and reference memory. Reference memory was established by training pigeons to discriminate between the comparison cues used in delayed matching as S+ and S-- stimuli. Delayed matching retention tests then measured accuracy when working and reference memory were congruent and incongruent. In 4 experiments, it was shown that the interaction between working and reference memory is reciprocal: Strengthening either type of memory leads to a decrease in the influence of the other type of memory. A process dissociation procedure analysis of the data from Experiment 4 showed independence of working and reference memory, and a model of working memory and reference memory interaction was shown to predict the findings reported in the 4 experiments. [ABSTRACT FROM AUTHOR]

Memories for spatial locations often show systematic errors toward the central value of the surrounding region. The Category Adjustment (CA) model suggests that this bias is due to a Bayesian combination of categorical and metric information, which offers an optimal solution under conditions of uncertainty (Huttenlocher, Hedges, & Duncan, 1991). A fundamental assumption of this model is that representations of locations are unbiased but uncertain; during cohibination, greater metric uncertainty results in relatively greater emphasis on categorical information, ultimately leading to increased bias (but also minimizing error across multiple estimates). Sampaio and Wang (2009) have demonstrated that metric information is not lost during this combination process, supporting the CA model's assumption that underlying spatial representations are undistorted. Here, we examine the 2nd half of the CA model's central assumption: that increasing metric uncertainty drives the combination process. Participants recognized point locations within visually complex images in a 4-choice task. Our results indicate that individuals recognized the correct location over other, biased alternatives, confirming that metric information is unbiased at the time of retrieval. In addition, we found that, when participants make errors, they are more likely to select locations that are biased toward the category prototype. In Experiment 2, we demonstrate that categorically biased locations are most likely to be chosen under conditions of uncertainty. Indeed, under these conditions, categorically biased locations were chosen more frequently than the correct location. These results suggest that systematic errors are the result of combination across multiple levels of spatial representations that are undistorted but somewhat uncertain. [ABSTRACT FROM AUTHOR]

Three experiments investigated whether navigation is less efficient across boundaries than within boundaries. In an immersive virtual environment, participants learned objects' locations in a large room or a small room. Participants then pointed to the objects' original locations after physically walking a circuitous path without vision. For participants who learned the objects in the large room, the testing position and the learning position were in the same room so that participants did not cross boundaries before testing; for participants who learned the objects in the small room, the testing position and the learning position were in 2 different rooms so that participants crossed boundaries before testing. Participants who learned the objects in the large room, during testing, either saw cues indicating the targets' locations (piloting group) or not (path integration group). Participants who learned the objects in the small room, during testing did not see any cues correctly indicating the targets' locations. The results showed that pointing accuracy was higher for those who learned the objects in the large room and in the piloting group than for those who learned the objects in the small room. However, this cross-boundary cost did not occur when we contrasted participants who learned objects in the large room and in the path integration group with participants who learned in a small room. These results suggested that navigation that relies on path integration only is not sensitive to boundary crossing, although navigation that relies on piloting is less efficient across boundaries than within boundaries. [ABSTRACT FROM AUTHOR]

Age-related cognitive impairments are particularly prevalent in forms of learning that require a functionally intact hippocampal formation, such as spatial and declarative learning. However, there is notable heterogeneity in the cognitive abilities of aged subjects. To date, few studies have determined whether age-related impairments on one learning task relate to impairments on different learning tasks that engage overlapping cognitive processes. Here, we hypothesized that aged animals that were impaired on 1 hippocampal-dependent behavioral procedure would be impaired on a second hippocampal-dependent procedure. Conversely, aged animals that were unimpaired on 1 hippocampal-dependent task would be unimpaired with a subsequent hippocampal-dependent form of learning. To test these hypotheses, we trained young (2-3 months old) and aged (28-29 months old) F344XBN male rats with trace eyeblink conditioning, followed by the Morris water maze. Half of aged rats were impaired during trace conditioning. Nearly half of aged animals were also impaired during water maze probe testing. Performance during trace conditioning correlated with performance during water maze testing in aged animals. Further analyses revealed that, as a group, aged animals that were impaired on 1 hippocampal-dependent task were impaired on both tasks. Conversely, aged animals that were unimpaired on 1 task were unimpaired on both tasks. Together, these results suggest that aged-related impairments on 1 hippocampal-dependent task predict age-related impairments on a second hippocampal-dependent procedure. These results have implications for assigning personalized therapeutics to ameliorate age-related cognitive decline. [ABSTRACT FROM AUTHOR]

The spatial memory for the last position occupied by a moving target is usually displaced forward in the direction of motion. Interpreted as a mental analogue of physical momentum, this phenomenon was coined representational momentum (RM). As momentum is given by the product of an object's velocity and mass, both these factors came to be under scrutiny in RM studies, the goal being to provide support for the internalization hypothesis. Although velocity was found to determine RM's magnitude, possible effects of mass were more elusive. Recently, an effect of target size on RM was reported, adding to previous findings that bigger targets were more mislocalized downward in the direction of gravity (via perceived heaviness and representational gravity, RG). The aim in the present research was to test that those outcomes reflect an internalization of momentum by excluding oculomotor factors. The results showed that an effect of target size, when it emerged, could be accounted for by a foveal bias such that bigger targets were more displaced toward gaze than were smaller ones. Specific contingencies between eye movements and target size seem to account for previous reports regarding the alleged effects of perceived mass on both RM and RG. This phenomenon seems furthermore to be modulated by the presence of other visual elements (fixation point) and the range of target velocities. These outcomes are taken as a rebuttal to the claim that cognitive analogues of mass or heaviness are responsible for previously reported effects of target size on both RM and RG. [ABSTRACT FROM AUTHOR]

The mammillary bodies and their projections via the mammilliothalamic tract to the anterior thalamic nuclei are known to be important for spatial memory in rodents, but their precise role remains unclear. To determine whether transection of the mammilliothalamic tract can produce deficits on tests of spatial memory even when the navigational demands placed on the animal are limited, rats with discrete mammilliothalamic tract lesions were tested on the ability to use distal visual cues to discriminate between 2 locations within a room, irrespective of the direction traveled (Experiment 1). Animals with mammilliothalamic tract lesions acquired this task more slowly and less accurately than control animals. Consistent with this impairment in discriminating different spatial locations, the same lesions also severely disrupted object-in-place memory but spared performance on standard tests of object recognition memory (Experiment 2). Finally, to compare performance on a task that is known to be sensitive to mammilliothalamic transection and requires animals to actively navigate within their environment, the effect of the lesions on spatial working memory in the radial-arm maze was examined. Taken together, the results suggest that even when there are little or no navigational demands, mammilliothalamic tract damage still results in impoverished encoding of spatial location [ABSTRACT FROM AUTHOR]

Working memory is typically defined as a system devoted to the simultaneous maintenance and processing of information. However, the interplay between these 2 functions is still a matter of debate in the literature, with views ranging from complete independence to complete dependence. The time-based resource-sharing model assumes that a central bottleneck constrains the 2 functions to alternate in such a way that maintenance activities postpone concurrent processing, with each additional piece of information to be maintained resulting in an additional postponement. Using different kinds of memoranda, we examined in a series of 7 experiments the effect of increasing memory load on different processing tasks. The results reveal that, insofar as attention is needed for maintenance, processing times linearly increase at a rate of about 50 ms per verbal or visuospatial memory item, suggesting a very fast refresh rate in working memory. Our results also show an asymmetry between verbal and spatial information, in that spatial information can solely rely on attention for its maintenance while verbal information can also rely on a domain-specific maintenance mechanism independent from attention. The implications for the functioning of working memory are discussed, with a specific focus on how information is maintained in working memory. [ABSTRACT FROM AUTHOR]

In an unfamiliar environment, searching for and navigating to a target requires that spatial information be acquired, stored, processed, and retrieved. In a study encompassing all of these processes, participants acted as taxicab drivers who learned to pick up and deliver passengers in a series of small virtual towns. We used data from these experiments to refine and validate MAGELLAN, a cognitive map-based model of spatial learning and wayfinding. MAGELLAN accounts for the shapes of participants' spatial learning curves, which measure their experience-based improvement in navigational efficiency in unfamiliar environments. The model also predicts the ease (or difficulty) with which different environments are learned and, within a given environment, which landmarks will be easy (or difficult) to localize from memory. Using just 2 free parameters, MAGELLAN provides a useful account of how participants' cognitive maps evolve over time with experience, and how participants use the information stored in their cognitive maps to navigate and explore efficiently. [ABSTRACT FROM AUTHOR]

We investigated how humans encode large-scale spatial environments using a virtual taxi game. We hypothesized that if 2 connected neighborhoods are explored jointly, people will form a single integrated spatial representation of the town. However, if the neighborhoods are first learned separately and later observed to be connected, people will form separate spatial representations; this should incur an accuracy cost when inferring directions from one neighborhood to the other. Interestingly, our data instead suggest that people have a very strong tendency to form local representations, regardless of whether the neighborhoods were learned together or separately. Only when all visible distinctions between neighborhoods were removed did people behave as if they formed one integrated spatial representation. These data are broadly consistent with evidence from rodent hippocampal place cell recordings in connected boxes, and with hierarchical models of spatial coding. [ABSTRACT FROM AUTHOR]

An influential theory of spatial navigation states that the boundary shape of an environment is preferentially encoded over and above other spatial cues, such that it is impervious to interference from alternative sources of information. We explored this claim with 3 intradimensional-extradimensional shift experiments, designed to examine the interaction of landmark and geometric features of the environment in a virtual navigation task. In Experiments 1 and 2, participants were first required to find a hidden goal using information provided by the shape of the arena or landmarks integrated into the arena boundary (Experiment 1) or within the arena itself (Experiment 2). Participants were then transferred to a different-shaped arena that contained novel landmarks and were again required to find a hidden goal. In both experiments, participants who were navigating on the basis of cues that were from the same dimension that was previously relevant (intradimensional shift) learned to find the goal significantly faster than participants who were navigating on the basis of cues that were from a dimension that was previously irrelevant (extradimensional shift). This suggests that shape information does not hold special status when learning about an environment. Experiment 3 replicated Experiment 2 and also assessed participants' recognition of the global shape of the navigated arenas. Recognition was attenuated when landmarks were relevant to navigation throughout the experiment. The results of these experiments are discussed in terms of associative and non-associative theories of spatial learning. [ABSTRACT FROM AUTHOR]

The perspective-taking task is one of the most common paradigms used to study the nature of spatial memory, and better performance for certain orientations is generally interpreted as evidence of spatial representations using these reference directions. However, performance advantages can also result from the relative ease in certain transformations/rotations. To differentiate spatial memory from spatial transformations, the present study took a new approach based on the hypothesis that responses may be biased toward the original representation but not a transformed one. Participants memorized a regular target array and then judged the relative direction between 2 targets while imagining facing various directions. Their response time and absolute errors showed the standard advantages at 4 imagined orientations. In contrast, an attraction analysis suggested that only 1 orientation was represented in memory, whereas performance advantages at other orthogonal orientations were due to lower transformation costs and should not be interpreted as spatial representations. These findings challenged the traditional performance-based interpretations of perspective change tasks and provided a new research paradigm to differentiate spatial representations from spatial transformations. [ABSTRACT FROM AUTHOR]

Five experiments investigated how human adults use landmark arrays in the immediate environment to reorient relative to the local environment and relative to remote cities. Participants learned targets' directions with the presence of a proximal 4 poles forming a rectangular shape and an array of more distal poles forming a rectangular shape. Then participants were disoriented and pointed to targets with the presence of the proximal poles or the distal poles. Participants' orientation was estimated by the mean of their pointing error across targets. The targets could be 7 objects in the immediate local environment in which the poles were located or 7 cities around Edmonton (Alberta, Canada) where the experiments occurred. The directions of the 7 cities could be learned from reading a map first and then from pointing to the cities when the poles were presented. The directions of the 7 cities could also be learned from viewing labels of cities moving back and forth in the specific direction in the immediate local environment in which the poles were located. The shape of the array of the distal poles varied in salience by changing the number of poles on each edge of the rectangle (2 vs. 34). The results showed that participants regained their orientation relative to local objects using the distal poles with 2 poles on each edge; participants could not reorient relative to cities using the distal pole array with 2 poles on each edge but could reorient relative to cities using the distal pole array with 34 poles on each edge. These results indicate that use of cues in reorientation depends not only on the cue salience but also on which environment people need to reorient to. [ABSTRACT FROM AUTHOR]

Visual attention and visual working memory exert severe capacity limitations on cognitive processing. Impairments in both functions may exacerbate the social and communication deficits seen in children with an autism spectrum disorder (ASD). This study characterizes spatial working memory and visual attention in school-age children with high-functioning autism. Children with ASD, and age, gender, and IQ-matched typically developing (TD) children performed 2 tasks: a spatial working memory task and an attentive tracking task. Compared with TD children, children with ASD showed a more pronounced deficit in the spatial working memory task than the attentive tracking task, even though the latter placed significant demands on sustained attention, location updating, and distractor inhibition. Because both groups of children were sensitive to configuration mismatches between the sample and test arrays, the spatial working memory deficit was not because of atypical organization of spatial working memory. These findings show that attention and working memory are dissociable, and that children with ASD show a specific deficit in buffering visual information across temporal discontinuity. [ABSTRACT FROM AUTHOR]

Four experiments investigated the manner in which people use spatial reference directions to organize spatial memories of 2 conceptually nested layouts. Participants learned directions of 8 remote cities centered to Beijing or Edmonton, where the experiments occurred, using a map or using direct pointing. The map and the environment were aligned, and participants faced north (0°). Participants also learned locations of 7 objects on a table. Participants faced north (0°) during learning but were instructed to learn the layout along the northwest-southeast (45°-225°) axis. Judgments of relative direction (imagine you are standing at X, facing Y, point to Z) were used to determine spatial reference directions in retrieval of bearings between 2 objects or 2 cities. The results showed that when the tested bearing and the imagined heading were within an array, participants used 0° as the reference direction in retrieving bearings between cities but used 45°-225° to retrieve bearings between objects. When the tested bearing and the imagined heading were across 2 arrays, participants used the reference direction of the array from which the tested bearing was. These results indicated that bearings between items within an array were represented only with respect to the reference directions of this array and the relationship between spatial reference directions in these 2 arrays was also represented. [ABSTRACT FROM AUTHOR]

Rodents rely heavily on odor detection, discrimination, and memory to locate food, find mates, care for pups, and avoid predators. Estrogens have been shown to increase memory retention in rodents performing spatial memory and object placement tasks. Here we evaluate the extent to which 17β-estradiol modulates memory formation and duration in the olfactory system. Adult CD-1 mice were gonadectomized and given either systemic 17β-estradiol replacement, local 17β-estradiol in the main olfactory bulb, or no replacement. Before performing the behavioral task the mice were given saline or PHTPP (an estrogen receptor β [ER-β] antagonist) via bilateral infusion into the main olfactory bulb. As the beta-type estrogen receptor (ER-β) is more abundant than the alpha-type estrogen receptor in the murine main olfactory bulb, the current study focuses on 17β-estradiol and its interactions with ERβ. Habituation, a simple, nonassociative learning task in which an animal is exposed to the same odor over successive presentations, was used to evaluate the animals' ability to detect odors and form an olfactory memory. To evaluate memory duration, we added a final trial of intertrial interval time (30 or 60 min) in which we presented the habituated odor. Neither surgical nor drug manipulation affected the ability of mice to detect or habituate to an odor. After habituation, gonadectomized 17β-estradiol-treated mice retained memory of an odor for 30 min, whereas non-estradiol-treated, 17β-estradiol+ERβ antagonist (PHTPP), and untreated male mice did not remember an odor 30 min after habituation. The results show that both systemic and local bulbar infusions of 17β-estradiol enhance odor memory duration in mice. [ABSTRACT FROM AUTHOR]

The head-direction (HD) signal is believed to originate in the dorsal tegmental nucleus (DTN) and lesions to this structure have been shown to disrupt HD cell firing in other areas along the HD cell circuit. To investigate the role of the DTN in spatial navigation, rats with bilateral, electrolytic (Experiment 1), or neurotoxic (Experiment 2) lesions to the DTN were compared with sham controls on two tasks that differed in difficulty and could be solved using directional heading. Rats were first trained on a direction problem in a water T maze where they learned to travel either east or west from two locations in the experimental room. DTN-lesioned rats were impaired relative to sham controls, both early in training, on the first block of eight trials, and on the total trials taken to reach criterion. In the food-foraging task, rats were trained to leave a home cage at the periphery of a circular table, find food in the center of the table and return to the home cage. Again, DTN-lesioned rats were impaired relative to sham rats, making more errors on the return component of the foraging trip. These data extend previous cell-recording studies and behavioral tests in which rats with electrolytic DTN lesions were used, and they demonstrate the importance of the direction system to spatial learning. [ABSTRACT FROM AUTHOR]

A considerable amount of research has demonstrated that animals can use different strategies when learning about, and navigating within, their environment. Since the influential research of Packard and McGaugh (1996), it has been widely accepted that, early in learning, rats use a flexible dorsal hippocampal-dependent place strategy. As learning progresses, they switch to a less effortful and more automatic dorsolateral caudate-dependent response strategy. However, supporting literature is dominated by the use of appetitively motivated tasks, using food reward. Because motivation often plays a crucial role in guiding learning, memory, and behavior, we examined spatial learning strategies of rats in an escape-motivated submerged T-maze. In Experiment 1, we observed rapid learning and the opposite pattern as that reported in appetitively motivated tasks. Rats exhibited a response strategy early in learning before switching to a place strategy, which persisted over extensive training. In Experiment 2, we replicated Packard and McGaugh's (1996) observations, using the apparatus and procedures as in Experiment 1, but with food reward instead of water escape. Mechanisms for, and implications of, this motivational modulation of spatial learning strategy are considered. [ABSTRACT FROM AUTHOR]

Choice by exclusion involves selecting a rewarded stimulus by rejecting alternatives that are unlikely to be rewarded. It has been proposed that in corvids, exclusion is an adaptive specialization for caching that, together with object permanence and observational spatial memory, enhances a bird's ability to keep track of the contents of caches. Thus, caching species are predicted to perform well in tasks requiring exclusion. We tested this prediction by assessing the performance of Eurasian jays (Garrulus glanda-rius), a highly specialized cacher, in a two-way object choice task in which food was hidden in 1 of 2 cups. Consistent with the corvids' capacity for observational spatial memory, jays were highly accurate when shown the location of the food reward. However, the jays failed to exclude the empty cup when shown its contents. This failure to select the baited cup when shown the empty cup was possibly due to jays attending to the experimenter's movements and erroneously selecting the empty cup by responding to these local enhancement cues. To date, no corvids have been tested in an auditory two-way object choice task. Testing exclusion in the auditory domain requires that a bird use the noise produced when the baited cup is shaken to locate the reward. Although jays chose the baited cup more frequently than predicted by chance, their performance did not differ from trials controlling for the use of conflicting cues provided by the experimenter. Overall, our results provide little support for the hypothesis that caching has shaped exclusion abilities in corvids. [ABSTRACT FROM AUTHOR]

Whereas maps primarily represent the 2-dimensional layout of the environment, people are also aware of the 3-dimensional layout of their environment. An experiment conducted on a small college campus tested whether the remembered slants of familiar paths were precisely represented. Three measures of slant (verbal, manual, and pictorial) were collected in 2 different between-subject conditions (perception and memory) for 5 familiar paths on the campus of Swarthmore College, ranging in slant from 0.5° to 8.6°. Estimates from memory and from perception did not differ for any of the measures. Moreover, estimates from all measures, though different in mean value, were correlated within participant, suggesting a common underlying representation was consulted in all cases. [ABSTRACT FROM AUTHOR]

Mou, Zhao, and McNamara (2007) proposed the "intrinsic model of human spatial memory," which posits that a viewer's memory of an array of objects will exhibit a preferred direction that is aligned with an intrinsic axis of the array. They defined intrinsic axes as salient axes created in part by the physical (geometric) properties of the array. To date, these geometric characteristics have received little research attention. We begin such an endeavor by evaluating the role of symmetry and orthogonality (i.e., number of right angles in an array of objects) in spatial memory. Participants viewed a layout of objects from a single (Experiment 1) viewpoint or 2 (Experiment 2) viewpoints and then judged relative directions within the layout from memory. Orthogonality and symmetry were associated with decreased reliance on egocentric reference systems but were qualified by a generally greater reliance on egocentric reference frames than is common in the literature. Indeed, for only 1 array--a highly orthogonal and symmetric one--did participants consistently respond nonegocentrically. We suggest that overuse of this array in the literature has led to an overestimation of the importance of allocentricity in spatial memory. [ABSTRACT FROM AUTHOR]

The hippocampal formation has been associated with a wide variety of functions including spatial navigation and planning, memory encoding and retrieval, relational processing, novelty detection, and imagination. These functions are dissimilar in terms of their behavioral consequences and modality of representation. Consequently, theoretical standpoints have focused on explaining the role of the hip-pocampal formation in terms of either its spatial or nonspatial functions. Contrary to this dichotomy, we propose that it is essential to look beyond these traditional boundaries between mnemonic and spatial functions and focus instead on the processes that these functions have in common. In this framework, we use electrophysiology data from the spatial domain to predict effects on the systems level, both in spatial and nonspatial domains. We initially outline the results of studies that have used findings from spatial navigation in rodents to predict the patterns of brain activity observable in people who are exploring virtual environments. We discuss how certain properties of space-defining neurons enable space to be represented as a mental map of interconnected locations, which are expressed at multiple spatial scales in separate modules in the hippocampal formation. We then suggest that memories are also organized in networks, characterized by mnemonic and temporal hierarchies. We finish by discussing how virtual-reality techniques can be used to create novel lifelike episodes allowing us to look at episodic memory processes while multivariate analysis tools can be used to explore the organizational structure of mnemonic networks. [ABSTRACT FROM AUTHOR]

Visual tracking abilities are limited to only a few objects at a time. When do errors arise? We hypothesized that some errors arise prior to tracking; specifically, during the first moments of a trial because of an inability to correctly perceive the number of targets in a display. To test this hypothesis, we modified a basic multiple object tracking (MOT) task in two ways: (1) we distilled the first moments of MOT into a static working memory task, requiring participants to remember and then identify targets among nontargets in displays without motion; (2) we unconstrained the number of responses a participant could make, asking them to terminate each trial when they felt that they had made an adequate number of responses. In Experiment I, participants made the wrong number of responses in a considerable number of trials, and they tendered the wrong number of responses more frequently with larger loads. Comparisons across different delay durations demonstrated that these results were not caused by temporal decay. Follow-up experiments produced similar results when participants stated the cardinal number of targets perceived in a static trial (Experiment 2), and when they reported whether or not a test display included the same number of targets as a memory display (Experiment 3). Finally, with a typical tracking duration, participants also produced the wrong number of responses frequently (Experiment 4). Thus, some of the difficulty associated with MOT originates from uncertainty about the number of targets at the start of an episode. [ABSTRACT FROM AUTHOR]

Part-set cuing inhibition refers to the counterintuitive finding that hints--specifically, part of the set of to-be-remembered information--often impair memory performance in free recall tasks. Although inhi-bition is the most commonly reported result, part-set cuing facilitation has been shown with serial order tasks. The present study examined the influence of part-set cuing for spatial locations using novel methods and materials. Participants viewed the construction of Snap Circuit objects and then attempted to reconstruct the objects in either the presence or absence of part-set cues. Two experiments revealed robust part-set cuing facilitation on the spatial memory tasks. Generally, these results are consistent with the predictions of the retrieval strategy disruption hypothesis (e.g. D. R. Basden & Basden, 1995) and the 2- and 3-mechanism accounts of part-set cuing (Bäuml & Asian, 2006: Bäuml & Samenieh. 2012). [ABSTRACT FROM AUTHOR]

Four experiments examined the roles of extended surfaces and the number of points in the boundary superiority effect in goal localization. Participants learned the locations of 4 objects in the presence of a boundary, landmarks, or both in an immersive virtual environment by reproducing the locations with feedback. Participants then localized the objects in the presence of either the boundary or the landmarks during testing without feedback. The results showed that when both 1 landmark and a circular boundary were presented during learning, localization error during testing increased significantly when only the landmark was presented during testing, whereas localization error did not increase when only the boundary was presented during testing, thus demonstrating a boundary superiority effect. This boundary superiority effect was not observed when 36 landmarks forming a circle and a circular boundary were presented during learning. The landmark superiority effect was observed when 36 landmarks, forming a circular shape, and l/36th part of the circular boundary were presented during learning. Furthermore, when a varied number of landmarks were presented with a circular boundary during learning, the localization error when the boundary was removed during testing was negatively correlated with the number of the landmarks. These results indicate that the superiority of a circular boundary to a landmark might be due to the larger number of points in the circular boundary but not due to the extended surface of the circular boundary. [ABSTRACT FROM AUTHOR]

Orientation dependence in spatial memory has often been interpreted in terms of accessibility: Object locations are encoded relative to a reference orientation that affords the most accurate access to spatial memory. An open question, however, is whether people naturally use this "preferred" orientation whenever recalling the space. We tested this question by asking participants to locate buildings on a familiar campus from various imagined locations, without specifying the heading to be assumed. We then used these pointing judgments to infer the approximate heading participants assumed at each location. Surprisingly, each location showed a unique assumed heading that was consistent across participants and seemed to reflect episodic or visual properties of the space. This result suggests that although locations are encoded relative to a reference orientation, other factors may influence how people choose to access the stored information and whether they appeal to long-term spatial memory or other more sensory-based stores. [ABSTRACT FROM AUTHOR]

Normal aging impairs the representation and integration (binding) of spatial and temporal Context in episodic memory. We directly compare age differences in episodic memory in relation to processing spatial and temporal context. As part of the COGITO study, 101 younger and 103 older participants trained an object-location serial recall task for 100 sessions. Training exacerbated the recall deficit of older relative to younger adults. Younger adults improved in recall performance on both spatial and temporal dimensions. In contrast, older adults improved on the spatial dimension only. Individual differences in pretest performance and change were positively correlated across dimensions among younger adults but negatively related among older adults. We conclude that older adults are impaired at simultaneously processing spatial and temporal context and preferentially process spatial at the expense of temporal context. [ABSTRACT FROM AUTHOR]

In recalling a list of previously experienced items, participants are known to organize their responses on the basis of the items' semantic and temporal similarities. Here, we examine how spatial information influences the organization of responses in free recall. In Experiment 1, participants studied and subsequently recalled lists of landmarks. In Experiment 2, participants played a game in which they delivered objects to landmarks in a virtual environment and later recalled the delivered objects. Participants in both experiments were simply asked to recall as many items as they could remember in any order. By analyzing the conditional probabilities of recall transitions, we demonstrate strong spatial and temporal organization of studied items in both experiments. [ABSTRACT FROM AUTHOR]

To determine what factors are important for minimizing interference effects in spatial memory, Clark's Nutcrackers, Nucifraga columbiana were tested for their spatial memory for two serial lists of locations per day. In this experiment two unique landmark sets were either different between List 1 and List 2 or the same. We found that Nutcrackers were most susceptible to interference when the landmark sets were the same. This study suggests that repeatedly testing animal memory in the same room, with the same cues, can hamper recall due to interference. [ABSTRACT FROM AUTHOR]

Younger and older adults who were either monolingual or bilingual were tested with verbal and spatial working memory (WM) span tasks. Aging was associated with a greater decline in spatial WM than in verbal WM, but the age-related declines were equivalent in both language groups. The bilingual participants outperformed the monolinguals in spatial WM, but achieved lower levels of performance than monolinguals in verbal WM. This interaction between bilingualism and WM domain was also consistent across the adult life span. These results are discussed in terms of the interactions between a domain-general executive processing advantage for bilinguals and the domain-specific content of particular WM tasks. [ABSTRACT FROM AUTHOR]

The development of spatial navigation in children depends not only on remembering which landmarks lead to a goal location but also on developing strategies to deal with changes in the environment or imperfections in memory. Using cue combination methods, the authors examined 3- and 4-year-old children's memory for different types of spatial cues and the spatial strategies that they use when those cues are in conflict. Children were taught to search for a toy in 1 of 4 possible hiding locations. Children were then tested on transformations of the array of locations. The transformations dissociated the different types of cues by putting them in conflict with one another. The authors were especially interested in the use of a majority strategy, by which children choose to search in the location indicated by the greatest number of cue types rather than relying on a preferred cue type. Children's memory for spatial cues and their strategies varied both by age and by experimental setup. In Experiment 1, both 3- and 4-year-old children preferred to use the distinct landmarks coincident with the hiding locations over any other types of cues and showed no use of a majority strategy. However, in Experiment 2, when the coincident landmarks were moved adjacent to the hiding locations, both 3- and 4-year-old children preferred to search in the position of the hiding location relative to the array. Furthermore, 4-year-old children in Experiment 2 showed better memory for individual types of cues and the emergence of a majority strategy. [ABSTRACT FROM AUTHOR]

This study describes a novel spatial memory paradigm for monkeys and reports the effects of neonatal damage to the hippocampus on performance in adulthood. Monkeys were trained to forage in eight boxes hung on the walls of a large enclosure. Each box contained a different food item that varied in its intrinsic reward value, as determined from food preference testing. Monkeys were trained on a spatial and a cued version of the task. In the spatial task, the boxes looked identical and remained fixed in location whereas in the cued task, the boxes were individuated with colored plaques and changed location on each trial. Ten adult Rhesus macaques (5 neonatal sham-operated and 5 with neonatal neurotoxic hippocampal lesions) were allowed to forage once daily until they preferentially visited boxes containing preferred foods. The data suggest that all monkeys learned to discriminate preferred from nonpreferred food locations, but that monkeys with neonatal hippocampal damage committed significantly more working memory errors than controls in both tasks. Furthermore, following selective satiation, controls altered their foraging pattern to avoid the satiated food, whereas lesioned animals did not, suggesting that neonatal hippocampal lesions prohibit learning of specific food-place associations. We conclude that whereas an intact hippocampus is necessary to form specific item-in-place associations, in its absence, cortical areas may support more broad distinctions between food types that allow monkeys to discrim-inate places containing highly preferred foods. [ABSTRACT FROM AUTHOR]

Studies of spontaneous behavior to assess memory are widespread, but often the relationships of objects to contexts and spatial locations are poorly defined. We examined whether object-location memory was maintained following global, but not local, changes to the geometric shape of an arena. Rats explored two trial-unique objects in 'a distinctively shaped arena before being exposed to two identical copies of one of these objects in a different shape in a different physical location. Rats preferentially explored objects that were novel in relation to their local geometric context rather than identifying both locations as novel in the global geometric context. [ABSTRACT FROM AUTHOR]

The spatial memory and foraging strategies of four adult captive-born American black bears (Ursus americanus) were explored in four experiments using a simulated foraging task. In the first three experiments, each session consisted of two phases separated by a delay: During the exploration phase, subjects foraged among a set of baited and unbaited sites. During the delay, the same locations were rebaited and subjects were released again and allowed to search the sites (search phase). In Experiments la and lb, different sites were baited each day and the interval between exploration and search was short (4 hr or 15 min). Subjects were not accurate at recovering the food items in either experiment. In Experiment 2, an "informed forager" paradigm was used in which one subject was given privileged knowledge about the location of the food during the exploration phase and was later released with an "uninformed" competitor during the search phase. The bears did not achieve above-chance recovery accuracy even in the presence of a competitor. In Experiment 3, the same two of four sites were continually baited and the bears were released simultaneously over a period of 20 days, with each baiting separated by 2 or 3 days. As a group, the bears' foraging accuracy with repeated baiting and longer intervals approached greater than chance accuracy. Results suggest some limitations on bears' use of spatial memory in captive environments, but reveal the potential for use of spatial memory over longer delays. [ABSTRACT FROM AUTHOR]