Spatial memories of virtual environments: How egocentric experience, intrinsic structure, and extrinsic structure interact

Previous research has uncovered three primary cues that influence spatial memory organization:egocentric experience, intrinsic structure (object defined), and extrinsic structure (environment defined). In the present experiments, we assessed the relative importance of these cues when all three were available during learning. Participants learned layouts from two perspectives in immersive virtual reality. In Experiment 1, axes defined by intrinsic and extrinsic structures were in conflict, and learning occurred from two perspectives, each aligned with either the intrinsic or the extrinsic structure. Spatial memories were organized around a reference direction selected from the first perspective, regardless of its alignment with intrinsic or extrinsic structures. In Experiment 2, axes defined by intrinsic and extrinsic structures were congruent, and spatial memories were organized around reference axes defined by those congruent structures, rather than by the initially experienced view. The findings are discussed in the context of spatial memory theory as it relates to real and virtual environments.     

Biased representations of the spatial structure of navigable environments

Recent studies (e.g., Shelton & McNamara in Cognitive Psychology, 43(4), 274–310, 2001; Valiquette, McNamara, & Smith in Memory and Cognition, 31(3), 479–489, 2003) have demonstrated that judgments of relative direction (JRD) access a single enduring orientation-dependent allocentric representation of the layout of objects in an environment, regardless of whether the space is viewed from one or multiple vantage points. Two experiments tested the limits of this phenomenon. In both experiments participants learned the locations of objects in a large room from two views: one view was aligned with salient environmental frames of reference (edges of the mat on which objects were placed and walls of the enclosing room) and expected to be preserved in long-term memory; the other view was misaligned and not expected to be preserved in long-term memory. The first experiment demonstrated that performing JRD between studying the misaligned view and studying the aligned view did not result in the misaligned view being maintained in long-term memory. The second experiment demonstrated that after studying the layout extensively from the misaligned view, 30 s of exposure to the aligned view (with no instructions to learn the layout from that view) resulted in the aligned but not the misaligned view being preserved in long-term memory. These findings indicate that the human spatial memory and navigation system is strongly biased to represent the spatial structure of navigable environments with reference directions or axes that are aligned with salient environmental frames of reference.     

Evidence of separable spatial representations in a virtual navigation task

Three experiments investigated spatial orientation in a virtual navigation task. Subjects had to adjust a homing vector indicating their end position relative to the origin of the path. It was demonstrated that sparse visual flow was sufficient for accurate path integration. Moreover, subjects were found to prefer a distinct egocentric or allocentric reference frame to solve the task. "Turners" reacted as if they had taken on the new orientation during turns of the path by mentally rotating their sagittal axis (egocentric frame). "Nonturners," by contrast, tracked the new orientation without adopting it (allocentric frame). When instructed to use their nonpreferred reference frame, both groups displayed no decline in response accuracy relative to their preferred frame; even when presented with reaction formats based on either ego or allocentric coordinates, with format unpredictable on a trial, both groups responded highly accurately. These findings support the assumption of coexisting spatial representations during navigation.     

Transfer of spatial behavior between different environments: implications for theories of spatial learning and for the role of the hippocampus in spatial learning

In 3 experiments, rats were required to find a submerged platform located in 1 corner of an arena that had 2 long and 2 short sides; they were then trained to find the platform in a new arena that also had 2 long and 2 short sides but a different overall shape. The platform in the new arena was easier to find if it was in a corner that was geometrically equivalent, rather than the mirror image, of the corner where it had previously been located. The final experiment revealed that hippocampal lesions impaired rats' ability to find the platform in these arenas. The results suggest that rats did not use the overall shape of the arena to locate the platform but relied on more local cues and that the hippocampus plays a role in navigation based on these cues.     

Visual landmarks facilitate rodent spatial navigation in virtual reality environments

Because many different sensory modalities contribute to spatial learning in rodents, it has been difficult to determine whether spatial navigation can be guided solely by visual cues. Rodents moving within physical environments with visual cues engage a variety of nonvisual sensory systems that cannot be easily inhibited without lesioning brain areas. Virtual reality offers a unique approach to ask whether visual landmark cues alone are sufficient to improve performance in a spatial task. We found that mice could learn to navigate between two water reward locations along a virtual bidirectional linear track using a spherical treadmill. Mice exposed to a virtual environment with vivid visual cues rendered on a single monitor increased their performance over a 3-d training regimen. Training significantly increased the percentage of time avatars controlled by the mice spent near reward locations in probe trials without water rewards. Neither improvement during training or spatial learning for reward locations occurred with mice operating a virtual environment without vivid landmarks or with mice deprived of all visual feedback. Mice operating the vivid environment developed stereotyped avatar turning behaviors when alternating between reward zones that were positively correlated with their performance on the probe trial. These results suggest that mice are able to learn to navigate to specific locations using only visual cues presented within a virtual environment rendered on a single computer monitor.     

Evidence against integration of spatial maps in humans: generality across real and virtual environments

A real-world open-field search task was implemented with humans as an analogue of Blaisdell and Cook’s (Anim Cogn 8:7–16, 2005) pigeon foraging task and Sturz, Bodily, and Katz’s (Anim Cogn 9:207–217, 2006) human virtual foraging task to 1) determine whether humans were capable of integrating independently learned spatial maps and 2) make explicit comparisons of mechanisms used by humans to navigate real and virtual environments. Participants searched for a hidden goal located in one of 16 bins arranged in a 4 × 4 grid. In Phase 1, the goal was hidden between two landmarks (blue T and red L). In Phase 2, the goal was hidden to the left and in front of a single landmark (blue T). Following training, goal-absent trials were conducted in which the red L from Phase 1 was presented alone. Bin choices during goal-absent trials assessed participants’ strategies: association (from Phase 1), generalization (from Phase 2), or integration (combination of Phase 1 and 2). Results were inconsistent with those obtained with pigeons but were consistent with those obtained with humans in a virtual environment. Specifically, during testing, participants did not integrate independently learned spatial maps but used a generalization strategy followed by a shift in search behavior away from the test landmark. These results were confirmed by a control condition in which a novel landmark was presented during testing. Results are consistent with the bulk of recent findings suggesting the use of alternative navigational strategies to cognitive mapping. Results also add to a growing body of literature suggesting that virtual environment approaches to the study of spatial learning and memory have external validity and that spatial mechanisms used by human participants in navigating virtual environments are similar to those used in navigating real-world environments.     

Functions and mental representation: the theoretical role of representations and its real nature

Representations are not only used in our folk-psychological explanations of behaviour, but are also fruitfully postulated, for example, in cognitive science. The mainstream view in cognitive science maintains that our mind is a representational system. This popular view requires an understanding of the nature of the entities they are postulating. Teleosemantic theories face this challenge, unpacking the normativity in the relation of representation by appealing to the teleological function of the representing state. It has been argued that, if intentionality is to be explained in teleological terms, then the function of a state cannot depend on its phylogenetical history, given the metaphysical possibility of a duplicate of an intentional being that lacks an evolutionary history (Swampman). In this paper, I present a method to produce, according to our current knowledge in genetic engineering, human-like individuals who are not the product of natural selection in the required sense. This variation will be used to shed light on the main replies that have been offered in the literature to the Swampman thought experiment. I argue that these replies are not satisfactory: representations should better not depend on natural selection. I conclude that a non-etiological notion of function is to be preferred for characterizing the relation of representation.     

The role of body-based sensory information in the acquisition of enduring spatial representations

Although many previous studies have shown that body-based sensory modalities such as vestibular, kinesthetic, and efferent information are useful for acquiring spatial information about one's immediate environment, relatively little work has examined how these modalities affect the acquisition of long-term spatial memory. Three groups of participants learned locations along a 146 m indoor route, and subsequently pointed to these locations, estimated distances between them, and constructed maps of the environment. One group had access to visual, proprioceptive, and inertial information, another had access to matched visual and matched inertial information, and another had access only to matched visual information. In contrast to previous findings examining transient, online spatial representations, our results showed very few differences among groups in the accuracy of the spatial memories acquired. The only difference was the improved pointing accuracy of participants who had access to proprioceptive information relative to that of participants in the other conditions. Results are discussed in terms of differential sensory contributions to transient and enduring spatial representations.     

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

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

Use of virtual environments to investigate development of spatial behavior and spatial knowledge of school-age children

This review aims to show the potential of using virtual environments in developmental spatial cognition research to advance empirical knowledge and theoretical insight. The facility for easy and economic variations of environmental features, the active, self-determined exploration, and the reliable registration of the navigation behavior using virtual environments allow investigating the development of spatial behavior and spatial knowledge in more detail. As a consequence, a dissociation between spatial behavior and spatial knowledge was observed, leading to the conclusion that spatial context has to be integrated further in any theoretical model regarding development of spatial cognition.     

Explaining sex differences in mental rotation: role of spatial activity experience

Males consistently outperform females on mental rotation tasks, such as the Vandenberg and Kuse (1978) Perceptual and Motor Skills, 47(2), 599–604, mental rotation test (MRT; e.g. Voyer et al. 1995) in Psychological Bulletin, 117, 250–265. The present study investigates whether these sex differences in MRT scores can be explained in part by early spatial activity experience, particularly those spatial activities that have been sex-typed as masculine/male-oriented. Utilizing an online survey, 571 ethnically diverse adult university students completed a brief demographic survey, an 81-item spatial activity survey, and the MRT. Results suggest that the significant relation between sex of the participant and MRT score is partially mediated by the number of masculine spatial activities participants had engaged in as youth. Closing the gap between males and females in spatial ability, a skill linked to science, technology, engineering, and mathematics success, may be accomplished in part by encouraging female youth to engage in more particular kinds of spatial activities.     

The role of goal representations in moving to temporal and spatial targets

Traditionally, movement kinematics are thought to reflect physical properties (e.g., position and time) of movement targets. However, targets may also evoke intentional goals like “to be in a certain position at a given time”. Therefore, kinematics may be viewed not as a reaction to stimuli, but rather as the means to attain intended goals. In the present study participants performed continuous reversal movements. It was first shown that kinematics towards temporal and spatial targets differ from kinematics away from those targets. Further, kinematics are different for movements to temporal (relatively short movement times, high and late peak velocity) and spatial (relatively long movement times, early peak velocity) targets (Experiments 1 and 2). In order to obtain evidence for the influence of goal representations on kinematics, combinations of temporal and spatial targets were investigated in Experiments 3 and 4. Specifically, the conditions were: spatial targets always present with varying temporal targets, temporal targets always present with varying spatial targets, and combined and separate spatial and temporal targets. Not only the physical features, but also how the targets were represented as movement goals, were important. Thus, movement kinematics do not simply reflect stimulus properties, but rather the representation of the intended goal.     

The role of goal representations in moving to temporal and spatial targets

Traditionally, movement kinematics are thought to reflect physical properties (e.g., position and time) of movement targets. However, targets may also evoke intentional goals like “to be in a certain position at a given time”. Therefore, kinematics may be viewed not as a reaction to stimuli, but rather as the means to attain intended goals. In the present study participants performed continuous reversal movements. It was first shown that kinematics towards temporal and spatial targets differ from kinematics away from those targets. Further, kinematics are different for movements to temporal (relatively short movement times, high and late peak velocity) and spatial (relatively long movement times, early peak velocity) targets (Experiments 1 and 2). In order to obtain evidence for the influence of goal representations on kinematics, combinations of temporal and spatial targets were investigated in Experiments 3 and 4. Specifically, the conditions were: spatial targets always present with varying temporal targets, temporal targets always present with varying spatial targets, and combined and separate spatial and temporal targets. Not only the physical features, but also how the targets were represented as movement goals, were important. Thus, movement kinematics do not simply reflect stimulus properties, but rather the representation of the intended goal.     

Enhancing inhibition: How impulsivity and emotional activation interact with different implementation intentions

Implementation intentions, a strategy in which a strong link is created between a cue and a to-be-performed action, have been shown to be efficacious in improving self-regulation. The relative efficacy of verbal and visual implementation intentions, however, has yet to be determined. Implementation intentions have also been shown to be inefficacious in participants with high impulsivity, specifically in individuals who reported having a high tendency to commit rash or regrettable actions as a result of intense affect (high urgency). Nevertheless, previous studies did not assess whether the individuals were in an emotional context at the time of the experiment. In the current study, we compared different forms of implementation intentions (verbal/visual/combined verbal–visual) on a computerized inhibition task while assessing impulsivity and emotional activation. The results showed that all types of implementation intentions improved inhibition performances significantly in participants with high urgency, but only when their emotional activation was low. There was no difference between the three types of implementation intentions.     

An attentional approach to study mental representations of different parts of the hand

The aim of this study is to investigate whether the fingers are represented separately from the palm. An exogenous spatial orientation paradigm was used where participants had to detect a tactile stimulus that could appear on the palm, the middle finger or the ring finger of the left hand. The tactile target was preceded by a non-predictive cue using different stimulus-onset asynchronies (SOA). We observed a Facilitation Effect in the palm and Inhibition of Return (IOR) for fingers using a short cue-target SOA, whereas the IOR was found in fingers and palm in long cue-target SOA. Also we observed a ‘Cue above Target’ effect (facilitation effect when the Cue had appeared distal to the target location in a vertical line) at the long SOA. Together, we suggest that the general pattern of results supports the proposed hypothesis about the different mental representation of fingers and palms, but with a considerable and hierarchical interrelation between them.     

The role of functionality in the mental representations of engineering students: some differences in the early stages of expertise

As engineers gain experience and become experts in their domain, the structure and content of their knowledge changes. Two studies are presented that examine differences in knowledge representation among freshman and senior engineering students. The first study examines recall of mechanical devices and chunking of components, and the second examines whether seniors represent devices in a more abstract functional manner than do freshmen. The most prominent differences between these 2 groups involve their representation of the functioning of groups of electromechanical components and how these groups of components interact to produce device behavior. Seniors are better able to construct coherent representations of devices by focusing on the function of sets of components in the device. The findings from these studies highlight some ways in which the structure and content of mental representations of design knowledge differ during the early stages of expertise acquisition.     

Online measurement of mental representations of complex spatial decision problems: Comparison of CNET and hard laddering

This paper introduces the online Causal Network Elicitation Technique (CNET), as a technique for measuring components of mental representations of choice tasks and compares it with the more common technique of online ‘hard’ laddering (HL). While CNET works in basically two phases, one in open question format and one as guided linking of attributes and benefits, HL works completely structured with revealed attributes and benefits. Mental representations of two activity travel tasks were collected with both techniques among members of a nationwide Dutch household panel. The results confirm the hypothesis that the revealed format of variables in HL has an effect on the indication of variables as the elicited mental representations are almost twice as big for HL than for CNET. Furthermore, it turned out that CNET is more sensitive in measuring shifts among attributes in the mental representations for situational changes of the activity-travel task.