Dynamic action in virtual environments: constraints on the accessibility of action knowledge in children and adults

In a series of three experiments, we probed the accessibility of action knowledge in different versions of a virtual environment (VE) with 7-year-old children and adults. Using a PHANToM haptic interface, participants performed a virtual throwing task in which they tried to propel a ball from a table to hit a target on the ground. In Experiments 1 and 2, the virtual scene was presented on a computer monitor, and, in Experiment 3, it was projected by using a video projector so that the vertical and horizontal dimensions and the spatial location of the VE corresponded to the real-world dimensions. Results indicate that action knowledge is accessible even in a nonimmersive VE, but also suggest that the need to recalibrate perceptual-motor mappings constrains the accessibility of this kind of intuitive knowledge.     

Virtual/real transfer of spatial knowledge: benefit from visual fidelity provided in a virtual environment and impact of active navigation

The purpose of this study was to evaluate the effect the visual fidelity of a virtual environment (VE) (undetailed vs. detailed) has on the transfer of spatial knowledge based on the navigation mode (passive vs. active) for three different spatial recall tasks (wayfinding, sketch mapping, and picture sorting). Sixty-four subjects (32 men and 32 women) participated in the experiment. Spatial learning was evaluated by these three tasks in the context of the Bordeaux district. In the wayfinding task, the results indicated that the detailed VE helped subjects to transfer their spatial knowledge from the VE to the real world, irrespective of the navigation mode. In the sketch-mapping task, the detailed VE increased performances compared to the undetailed VE condition, and allowed subjects to benefit from the active navigation. In the sorting task, performances were better in the detailed VE; however, in the undetailed version of the VE, active learning either did not help the subjects or it even deteriorated their performances. These results are discussed in terms of appropriate perceptive-motor and/or spatial representations for each spatial recall task.     

Field dependency and the sense of object-presence in haptic virtual environments.

Virtual environment (VE) users often report having a sense of being present in the virtual place or a sense that the virtual object is present in their environment. This sense of presence depends on both the technological fidelity (e.g., in graphics, haptics) and the users' cognitive/ personality characteristics. This study examined the correlation between user's cognitive style on the field-dependency dimension and the level of object-presence they reported in a haptic VE. Results indicated that field-independent individuals reported higher presence ratings compared to field-dependent participants. We hypothesize that field-independents' advantage in reorganizing the perceptual field and constructing it according to their previously acquired internal knowledge enables them to cognitively reconstruct the VE experience more efficiently by selectively attending only to the relevant cues and by filling in the gap of missing information with their previous knowledge and creative imagination. This active and creative cognitive process may be behind the enhanced sense of presence. In addition, we raise a possible linkage between field dependency, the sense of presence, and simulator sickness phenomenon.     

Individual differences in spatial learning from computer-simulated environments

A multivariate study examined relationships between the following factors: paper-and-pencil assessments of verbal and spatial ability, ability to form an accurate spatial representation of a large real-world environment, gender, computer attitudes and experience, proficiency with the navigational interface of a virtual environment (VE), and the ability to acquire and transfer spatial knowledge from a VE. Psychometrically assessed spatial ability and proficiency with the navigational interface were found to make substantial contributions to individual differences in the ability to acquire spatial information from a VE. Gender influenced many VE-related tasks, primarily through its relationship with interface proficiency and spatial ability. Measures of spatial knowledge of a VE maze were highly predictive of subsequent performance in a similar real-world maze, suggesting that VEs can be useful for training people about real-world spaces.     

Contrast Effects in Judgments of Health Hazards

Abstract

Researchers commonly use 2 models to explain contrast effects (CEs): the standard-of-comparison model and the set-reset model. The 2 models focus on the role of categorization to predict when a CE (instead of an assimilation effect) will happen, while minimizing the role of knowledge accessibility and relevance in determining whether any effect will occur. A 3rd model, the selective-accessibility model (F. Strack & T. Mussweiler, 1997), focuses on knowledge accessibility and relevance, but it is a model of assimilation effects in the anchoring bias. In the present study of CEs, the authors tested 3 predictions implied by the selective-accessibility model. The authors found a CE only when anchor- and target-rating dimensions matched and only in the 1 st of multiple targets rated. The CE required a minimum amount of attention to the anchor. These results support the account that selective knowledge accessibility and relevance play an important role in CEs.     

Transfer of route learning from virtual to real environments

The authors investigated the extent to which route learning in a virtual environment (VE) transfers to the real world. In Experiment 1, active VE exploration, on its own or with a map, produced better transfer of training than either no VE training at all or passive VE training; however, transfer was achieved after shorter training times with the map. Experiment 2 demonstrated that VE + map training was not superior to training with a map alone, and Experiment 3 demonstrated that the poorer performances observed after passive VE training were not simply due to a lack of attention but to the lack of active navigational decisions. The authors concluded that the present VE technology does not provide better route learning than studying a map.     

Contrast effects in judgments of health hazards

Researchers commonly use 2 models to explain contrast effects (CEs): the standard-of-comparison model and the set-reset model. The 2 models focus on the role of categorization to predict when a CE (instead of an assimilation effect) will happen, while minimizing the role of knowledge accessibility and relevance in determining whether any effect will occur. A 3rd model, the selective-accessibility model (F. Strack & T. Mussweiler, 1997), focuses on knowledge accessibility and relevance, but it is a model of assimilation effects in the anchoring bias. In the present study of CEs, the authors tested 3 predictions implied by the selective-accessibility model. The authors found a CE only when anchor- and target-rating dimensions matched and only in the 1st of multiple targets rated. The CE required a minimum amount of attention to the anchor. These results support the account that selective knowledge accessibility and relevance play an important role in CEs.     

First‐perspective alignment effects in a computer‐simulated environment

In Experiment 1, participants explored two desktop, virtual environments (VEs), each comprising three city streets connected at right angles; for each participant one VE was open and one was enclosed. Following the first VE exploration, orientation estimates to remembered test locations were most accurate when participants imagined themselves aligned, rather than 90° misaligned or 180° or contra‐aligned, with the first part of the route. In the second VE, the effect was attenuated and the data pattern conformed to that anticipated from an orientation‐free memory. Experiment 2 followed the procedure of Experiment 1, but omitted the alignment tests after the first VE; following the second VE exploration, orientation estimates presented a similar pattern to those in first test of Experiment 1. These data are discussed in terms of cognitive load.     

Manipulating perception versus action in recalibration tasks

We conducted six experiments to examine how manipulating perception versus action affects perception–action recalibration in real and imagined blindfolded walking tasks. Participants first performed a distance estimation task (pretest) and then walked through an immersive virtual environment on a treadmill for 10 min. Participants then repeated the distance estimation task (posttest), the results of which were compared with their pretest performance. In Experiments 1a, 2a, and 3a, participants walked at a normal speed during recalibration, but the rate of visual motion was either twice as fast or half as fast as the participants' walking speed. In Experiments 1b, 2b, and 3b, the rate of visual motion was kept constant, but participants walked at either a faster or a slower speed. During pre- and posttest, we used either a blindfolded walking distance estimation task or an imagined walking distance estimation task. Additionally, participants performed the pretest and posttest distance estimation tasks in either the real environment or the virtual environment. With blindfolded walking as the distance estimation task for pre- and posttest, we found a recalibration effect when either the rate of visual motion or the walking speed was manipulated during the recalibration phase. With imagined walking as the distance estimation task, we found a recalibration effect when the rate of visual motion was manipulated, but not when the walking speed was manipulated in both the real environment and the virtual environment. Discussion focuses on how spatial-updating processes operate on perception and action and on representation and action.     

3-D localization of virtual sound sources: Effects of visual environment, pointing method, and training

The ability to localize sound sources in three-dimensional space was tested in humans. In Experiment 1, naive subjects listened to noises filtered with subject-specific head-related transfer functions. The tested conditions included the pointing method (head or manual pointing) and the visual environment (VE; darkness or virtual VE). The localization performance was not significantly different between the pointing methods. The virtual VE significantly improved the horizontal precision and reduced the number of front-back confusions. These results show the benefit of using a virtual VE in sound localization tasks. In Experiment 2, subjects were provided with sound localization training. Over the course of training, the performance improved for all subjects, with the largest improvements occurring during the first 400 trials. The improvements beyond the first 400 trials were smaller. After the training, there was still no significant effect of pointing method, showing that the choice of either head- or manual-pointing method plays a minor role in sound localization performance. The results of Experiment 2 reinforce the importance of perceptual training for at least 400 trials in sound localization studies.     

Active versus passive learning and testing in a complex outside built environment

A review of the evidence on active and passive learning in virtual environments (VEs) suggests that both conditions have shown superiority under some conditions of learning and testing, but there is no consistent outcome pattern. Measures of transfer between virtual and real environments have also revealed a variety of outcomes. Following either active or passive learning in a VE, experiment 1 assessed measures of orientation and distance estimation in that VE and in a real-world equivalent environment. On measures of direct and relative distance, more accurate estimates were found for active than passive VE explorers. A suggestion was also noted for the orientation estimates to benefit from real-world rather than VE testing. With an improvement to the procedure, experiment 2 found similar real versus virtual orientation judgements, suggesting that an opportunity for active learning during the test procedure probably influenced orientation measures in experiment 1. We conclude that the effects of interactivity are unreliable and vary with the measures used, and that testing in virtual and real environments leads to similar outcomes.     

Spatial knowledge acquisition from maps and from navigation in real and virtual environments

In this study, the nature of the spatial representations of an environment acquired from maps, navigation, and virtual environments (VEs) was assessed. Participants first learned the layout of a simple desktop VE and then were tested in that environment. Then, participants learned two floors of a complex building in one of three learning conditions: from a map, from direct experience, or by traversing through a virtual rendition of the building. VE learners showed the poorest learning of the complex environment overall, and the results suggest that VE learners are particularly susceptible to disorientation after rotation. However, all the conditions showed similar levels of performance in learning the layout of landmarks on a single floor. Consistent with previous research, an alignment effect was present for map learners, suggesting that they had formed an orientation-specific representation of the environment. VE learners also showed a preferred orientation, as defined by their initial orientation when learning the environment. Learning the initial simple VE was highly predictive of learning a real environment, suggesting that similar cognitive mechanisms are involved in the two learning situations.     

Use of Virtual Environments for the Acquisition of Spatial Knowledge: Comparison Among Different Visual Displays

This experiment investigated the effects of three visual display systems differing in immersiveness: A wide field of view (FOV) 3-D helmet-mounted display (HMD); a 3-D HMD with a narrow FOV; and a stationary, rear-projection, wide screen display (WSD). Soldiers explored a virtual environment (VE) representing an actual, unfamiliar heliport. Measures of spatial knowledge of the heliport and presence were recorded. Pretest-posttest differences showed that exploration of the VE transferred to the actual heliport. Visual display had no effect on spatial knowledge of the heliport or on presence. Measures of susceptibility to presence correlated with reported presence only in the WSD condition. Results question popular notions about VEs, which assume that visual-spatial learning is more effective the more immersive the visual display.     

Lucky joint action

In this paper, I argue that joint action permits a certain degree of luck. The cases I have in mind exhibit the following structure: each participant believes that the intended ends of each robustly support the joint action. This belief turns out to be false. Due to lucky circumstances, the discordance in intention never becomes common knowledge. However, common knowledge of the relevant intentions would have undermined the joint action altogether. The analysis of such cases shows the extent to which common knowledge of the participants’ intentions can be harmful to joint action. This extends a recent line of research that has questioned the necessity of common knowledge in joint action.     

Warrant and action

I develop an approach to action and practical deliberation according to which the degree of epistemic warrant required for practical rationality varies with practical context. In some contexts of practical deliberation, very strong warrant is called for. In others, less will do. I set forth a warrant account, (WA), that captures this idea. I develop and defend (WA) by arguing that it is more promising than a competing knowledge account of action due to John Hawthorne and Jason Stanley. I argue that cases of warranted false belief speak in favor of (WA) and against the knowledge account. Moreover, I note some problems with an “excuse maneuver” that proponents of the knowledge account frequently invoke in response to cases of warranted false belief. Finally, I argue that (WA) may provide a strict invariantist account of cases that have been thought to motivate interest-relative or subject-sensitive theories of knowledge and warrant.     

Attending to what matters: Flexibility in adults’ and infants’ action perception

Action perception is selective in that observers attend to and encode certain dimensions of action over others. But how flexible is action perception in its selection of perceptual information? One possibility is that observers consistently attend to particular dimensions of action over others across different contexts. Another possibility, tested here, is that observers flexibly vary their attention to different dimensions of action based on the context in which action occurs. We investigated 9.5-month-old infants’ and adults’ ability to attend to drop height under varying contexts—aiming to drop an object into a narrow container versus a wide container. We predicted differential attention to increases in aiming height for the narrow container versus the wide container because an increase in aiming height has a differential effect on success (i.e., getting the object into the container) depending on the width of the container. Both adults and infants showed an asymmetry in their attention to aiming height as a function of context; in the wide container condition increases and decreases in aiming height were equally detectable, whereas in the narrow container condition observers more readily discriminated increases over decreases in aiming height. These results indicate that action perception is both selective and flexible according to context, aiding in action prediction and infants’ social–cognitive development more broadly.     

Perceiving virtual geographical slant: action influences perception

In 4 experiments, the authors varied the extent and nature of participant movement in a virtual environment to examine the influence of action on estimates of geographical slant. Previous studies showed that people consciously overestimate hill slant but can still accurately guide an action toward the hill (D. R. Proffitt, M. Bhalla, R. Gossweiler, & J. Midgett, 1995). Related studies suggest that one's potential to act may influence perception of slant and that distinct representations may independently inform perceptual and motoric responses. The authors found that in all conditions, perceptual judgments were overestimated and motoric adjustments were more accurate. The virtual environment allowed manipulation of the effort required to walk up simulated hills. Walking with the effort appropriate to the visual slant led to increased perceptual overestimation of slant compared with active walking with the effort appropriate to level ground, while visually guided actions remained accurate.     

Object processing in visual perception and action in children and adults

We investigated whether 6- and 7-year-olds and 9- and 10-year-olds, as well as adults, process object dimensions independent of or in interaction with one another in a perception and action task by adapting Ganel and Goodale's method for testing adults (Nature, 2003, Vol. 426, pp. 664-667). In addition, we aimed to confirm Ganel and Goodale's results in adults to reliably compare their processing strategies with those of children. Specifically, we tested the abilities of children and adults to perceptually classify (perception task) or grasp (action task) the width of a rectangular object while ignoring its length. We found that adults process object dimensions in interaction with one another in visual perception but independent of each other in action, thereby replicating Ganel and Goodale's results. Children processed object dimensions interactively in visual perception, and there was also some evidence for interactive processing in action. Possible reasons for these differences in object processing between children and adults are discussed.     

Belief-based action prediction in preverbal infants

Successful mindreading entails both the ability to think about what others know or believe, and to use this knowledge to generate predictions about how mental states will influence behavior. While previous studies have demonstrated that young infants are sensitive to others’ mental states, there continues to be much debate concerning how to characterize early theory of mind abilities. In the current study, we asked whether 6-month-old infants appreciate the causal role that beliefs play in action. Specifically, we tested whether infants generate action predictions that are appropriate given an agent’s current belief. We exploited a novel, neural indication of action prediction: motor cortex activation as measured by sensorimotor alpha suppression, to ask whether infants would generate differential predictions depending on an agent’s belief. After first verifying our paradigm and measure with a group of adult participants, we found that when an agent had a false belief that a ball was in the box, motor activity indicated that infants predicted she would reach for the box, but when the agent had a false belief that a ball was not in the box, infants did not predict that she would act. In both cases, infants based their predictions on what the agent, rather than the infant, believed to be the case, suggesting that by 6 months of age, infants can exploit their sensitivity to other minds for action prediction.