Seeing beyond the Target: Environmental Context Affects Distance Perception

Non-metric distance judgements are influenced by image projection geometry and field of view

Despite its mathematical simplicity and ubiquity in imaging technology, there has long been doubt about the ability of linear perspective to best represent human visual space, especially at wide-angle fields of view under natural viewing conditions. We investigated whether changes to image geometry had an impact on participants' performance, specifically in terms of non-metric distance estimates. Our multidisciplinary research team developed a new open-source image database to study distance perception in images by systematically manipulating target distance, field of view, and image projection using non-linear natural perspective projections. The database consists of 12 outdoor scenes of a virtual three-dimensional urban environment in which a target ball is presented at increasing distance, visualised using both linear perspective and natural perspective images, rendered, respectively, with three different fields of view: 100°, 120°, and 140° horizontally. In the first experiment (N = 52), we tested the effects of linear versus natural perspective on non-metric distance judgements. In the second experiment (N = 195), we investigated the influence of contextual and previous familiarity with linear perspective, and individual differences in spatial skills on distance estimations. The results of both experiments showed that distance estimation accuracy improved in natural compared with linear perspective images, particularly at wide-angle fields of view. Moreover, undertaking a training session with only natural perspective images led to more accurate distance judgements overall. We argue that the efficacy of natural perspective may stem from its resemblance to the way objects appear under natural viewing conditions, and that this can provide insights into the phenomenological structure of visual space.

Foot-related/walking macro-affordances are implicitly activated and preferentially guided by the framing distance of the environmental layout

As classically captured in the notion of affordance, the natural environment presents animals with multiple opportunities for action and locomotion appears as the privileged form of action to cover distance in the extrapersonal space/environment. We have recently described a facilitation effect, known as "macro-affordance", for the execution of walking-related actions in response to distant vs. near objects/locations in the extrapersonal space. However, since the manipulation of distance was coextensive to landmark-objects contained in the environment and to the environmental layout per se, the relative contribution of these two factors remains undetermined. In addition, since the effect was originally described in the context of an incidental priming paradigm, it is still unknown whether it was specifically associated with an implicit coding of environmental distance. Here, across three experiments, we examined the degree to which the "macro-affordance" effect reflects (i) the encoding of environmental vs. landmark-objects' distance, (ii) the involvement of an implicit vs. controlled system, (iii) a foot-effector specificity. The results showed that the "macro-affordance" effect is more efficiently triggered by the framing distance of the environmental layout (far/wide/panoramic vs. near/close/restricted) rather than of isolated landmark-objects in the environment and that it only emerges when the distance dimension is implicitly processed within the incidental priming paradigm. The results additionally suggested a specificity of the effect for foot- vs. hand-related actions. The present findings suggest that macro-affordances reflect an implicit coding of spatial features of the environmental layout and viewer-environment relationships that preferentially guide a walking-related exploration of the spatial environment.

Homing tasks performed using variations of crawling gait patterns reveal a role for attention in podokinetic path integration

Self-motion can be perceived via podokinetic information, that is, based upon the movements of the legs during legged locomotion. This information can be integrated in order to perceive a path of travel through the environment (i.e., via podokinetic path integration). Two types of podokinetic information have been distinguished by analyzing the patterns of bias that result from manipulating the gait patterns used in direct-route homing tasks. Each type of podokinetic information has been associated specific groupings of gaits that support equivalent perceptual measurements of self-motion. Specifically, gaits are grouped if they can be varied across the outbound and inbound phases of a homing task (e.g., walking outbound and jogging inbound) and the accuracy of homing task performances does not differ from matched-gait control conditions. Recently, it was theorized that different types of podokinetic information are related to the differences in the kinematic form of limb motions in these groupings of gaits. Here we test an alternative hypothesis, namely that attention plays a role in selecting the type of podokinetic information. In three experiments, we manipulated the crawling gait patterns used in direct-route homing tasks. Consistent with our hypotheses, we observe that self-motion is equivalently measured via crawling movement patterns that (1) have distinct kinematic forms, but that similarly direct participants' attention onto controlling the swing phase trajectories of their arms, and (2) have distinct inter-limb coordination patterns (i.e., pace vs. trot), but do not require attention to be specifically focused upon swing phase arm trajectories.

Perceiving distance in virtual reality: theoretical insights from contemporary technologies

Decades of research have shown that absolute egocentric distance is underestimated in virtual environments (VEs) when compared with the real world. This finding has implications on the use of VEs for applications that require an accurate sense of absolute scale. Fortunately, this underperception of scale can be attenuated by several factors, making perception more similar to (but still not the same as) that of the real world. Here, we examine these factors as two categories: (i) experience inherent to the observer, and (ii) characteristics inherent to the display technology. We analyse how these factors influence the sources of information for absolute distance perception with the goal of understanding how the scale of virtual spaces is calibrated. We identify six types of cues that change with these approaches, contributing both to a theoretical understanding of depth perception in VEs and a call for future research that can benefit from changing technologies. This article is part of the theme issue 'New approaches to 3D vision'.

Effect of landscape design on depth perception in classical Chinese gardens: A quantitative analysis using virtual reality simulation

It is common for visitors to have rich and varied experiences in the limited space of a classical Chinese garden. This leads to the sense that the garden’s scale is much larger than it really is. A main reason for this perceptual bias is the gardener’s manipulation of visual information. Most studies have discussed this phenomenon in terms of qualitative description with fragmented perspectives taken from static points, without considering ambient visual information or continuously changing observation points. A general question arises, then, on why depth perception can vary from one observation point to another along a garden path. To better understand the spatial experience in classical Chinese gardens, this study focused on variations in perceived depth among different observation points and aimed to identify influential visual information through psychophysical experimentation. As stimuli for the experiment, panoramic photos of Liu garden were taken from three positions at Lvyin Pavilion. Considering the effects of pictorial visual cues on depth perception, the photos were processed to create 18 kinds of stimuli (six image treatments * three positions). Two tasks were presented to the participants. In Task 1, 71 participants were asked to rate the depth value of the garden using the magnitude estimation method in a cave automatic virtual environment (CAVE). Statistical analysis of Task 1 revealed that depth values differed significantly among different viewpoints. In Task 2, participants were asked to compare 18 stimuli and 3D images presented on three connected monitors and to judge the depth of the garden using the adjustment method. The results of Task 2 again showed that depth values differed significantly among different viewpoints. In both tasks, ambient information (i.e., the perspective of interior space) significantly influenced depth perception.

Homing tasks and distance matching tasks reveal different types of perceptual variables associated with perceiving self-motion during over-ground locomotion

Self-motion perception refers to the ability to perceive how the body is moving through the environment. Perception of self-motion has been shown to depend upon the locomotor action patterns used to move the body through the environment. Two separate lines of enquiry have led to the establishment of two distinct theories regarding this effect. One theory has proposed that distances travelled during locomotion are perceived via higher order perceptual variables detected by the haptic perceptual system. This theory proposes that two higher order haptic perceptual variables exist, and that the implication of one of these variables depends upon the type of gait pattern that is used. A second theory proposes that self-motion is perceived via a higher order perceptual variable termed multimodally specified energy expenditure (MSEE). This theory proposes that the effect of locomotor actions patterns upon self-motion perception is related to changes in the metabolic cost of locomotion per unit of perceptually specified traversed distance. Here, we test the hypothesis that the development of these distinct theories is the result of different choices in methodology. The theory of gait type has been developed based largely on the results of homing tasks, whereas the effect of MSEE has been developed based on the results of distance matching tasks. Here we test the hypothesis that the seemly innocuous change in experimental design from using a homing task to using a distance matching task changes the type of perceptual variables implicated in self-motion perception. To test this hypothesis, we closely replicated a recent study of the effect of gait type in all details bar one-we investigated a distance matching task rather than a homing task. As hypothesized, this change yielded results consistent with the predictions of MSEE, and distinct from gait type. We further show that, unlike the effect of gait type, the effect of MSEE is unaffected by the availability of vision. In sum, our findings support the existence of two distinct types of higher order perceptual variables in self-motion perception. We discuss the roles of these two types of perceptual variables in supporting effective human wayfinding.

Environment width robustly influences egocentric distance judgments

Past work has suggested that perception of object distances in natural scenes depends on the environmental surroundings, even when the physical object distance remains constant. The cue bases for such effects remain unclear and are difficult to study systematically in real-world settings, given the challenges in manipulating large environmental features reliably and efficiently. Here, we used rendered scenes and crowdsourced data collection to address these challenges. In 4 experiments involving 452 participants, we investigated the effect of room width and depth on egocentric distance judgments. Targets were placed at distances of 2–37 meters in rendered rooms that varied in width (1.5–40 meters) and depth (6–40 meters). We found large and reliable effects of room width: Average judgments for the farthest targets in a 40-meter-wide room were between 16–33% larger than for the same target distances seen in a 1.5-meter-wide hallway. Egocentric distance cues and focal length were constant across room widths, highlighting the role of environmental context in judging distances in natural scenes. Obscuring the fine-grained ground texture, per se, is not primarily responsible for the width effect, nor does linear perspective play a strong role. However, distance judgments tended to decrease when doors and/or walls obscured more distant regions of the scene. We discuss how environmental features may be used to calibrate relative distance cues for egocentric distance judgments.

Target Constraints Influence Locomotion Pattern to the First Hurdle

The study examined to what extent the manipulation of hurdle height (0.76-m hurdle, low hurdle 0.50 m, and white stripe) would affect visual regulation strategies and kinematic reorganization when approaching the first hurdle. In addition, the impact of constraints as a training tool in terms of creating movement patterns functional for and representative of competitive movement models was assessed. The approach phase to the first hurdle of 13 physical education students with no previous experience in hurdling was video recorded and analyzed. Emergence of different footfall variability curves and movement coordination patterns suggests that participants interact differently with features of the performance context. Contrary to the white stripe, the hurdle height required participants to initiate regulation and distribute adjustments over a larger number of steps, and afforded the preparation for takeoff in order to clear the hurdle. In task design, manipulation of task constraints should offer valuable information regarding the dynamics of movement.

Estimating time-to-contact when vision is impaired

Often, we have to rely on limited information when judging time-to-contact (TTC), as for example, when driving in foul weather, or in situations where we would need reading glasses but do not have them handy. However, most existing studies on the ability to judge TTC have worked with optimal visual stimuli. In a prediction motion task, we explored to what extent TTC estimation is affected by visual stimulus degradation. A simple computer-simulated object approached the observer at constant speed either with clear or impaired vision. It was occluded after 1 or 1.5 s. The observers extrapolated the object’s motion and pressed a button when they thought the object would have collided with them. We found that dioptric blur and simulated snowfall shortened TTC-estimates. Contrast reduction produced by a virtual semi-transparent mask lengthened TTC estimates, which could be the result of distance overestimation or speed underestimation induced by the lower contrast or the increased luminance of the mask. We additionally explored the potential influence of arousal and valence, although they played a minor role for basic TTC estimation. Our findings suggest that vision impairments have adverse effects on TTC estimation, depending on the specific type of degradation and the changes of the visual environmental cues which they cause.

Distance Estimation in Virtual Reality Is Affected by Both the Virtual and the Real-World Environments

The experience in virtual reality (VR) is unique, in that observers are in a real-world location while browsing through a virtual scene. Previous studies have investigated the effect of the virtual environment on distance estimation. However, it is unclear how the real-world environment influences distance estimation in VR. Here, we measured the distance estimation using a bisection (Experiment 1) and a blind-walking (Experiments 2 and 3) method. Participants performed distance judgments in VR, which rendered either virtual indoor or outdoor scenes. Experiments were also carried out in either real-world indoor or outdoor locations. In the bisection experiment, judged distance in virtual outdoor was greater than that in virtual indoor. However, the real-world environment had no impact on distance judgment estimated by bisection. In the blind-walking experiment, judged distance in real-world outdoor was greater than that in real-world indoor. On the other hand, the virtual environment had no impact on distance judgment estimated by blind-walking. Generally, our results suggest that both the virtual and real-world environments have an impact on distance judgment in VR. Especially, the real-world environment where a person is physically located during a VR experience influences the person's distance estimation in VR.

The effect of navigation method and visual display on distance perception in a large-scale virtual building

Immersive virtual reality (VR) technology has become a popular method for fundamental and applied spatial cognition research. One challenge researchers face is emulating walking in a large-scale virtual space although the user is in fact in a small physical space. To address this, a variety of movement interfaces in VR have been proposed, from traditional joysticks to teleportation and omnidirectional treadmills. These movement methods tap into different mental processes of spatial learning during navigation, but their impacts on distance perception remain unclear. In this paper, we investigated the role of visual display, proprioception, and optic flow on distance perception in a large-scale building by manipulating four different movement methods. Eighty participants either walked in a real building, or moved through its virtual replica using one of three movement methods: VR-treadmill, VR-touchpad, and VR-teleportation. Results revealed that, first, visual display played a major role in both perceived and traversed distance estimates but did not impact environmental distance estimates. Second, proprioception and optic flow did not impact the overall accuracy of distance perception, but having only an intermittent optic flow (in the VR-teleportation movement method) impaired the precision of traversed distance estimates. In conclusion, movement method plays a significant role in distance perception but does not impact the configurational knowledge learned in a large-scale real and virtual building, and the VR-touchpad movement method provides an effective interface for navigation in VR.

For humans navigating without vision, navigation depends upon the layout of mechanically contacted ground surfaces

Navigation can be haptically guided. In specific, tissue deformations arising from both limb motions during locomotion (i.e., gait patterns) and mechanical interactions between the limbs and the environment can convey information, detected by the haptic perceptual system, about how the body is moving relative to the environment. Here, we test hypotheses concerning the properties of mechanically contacted environments relevant to navigation of this kind. We studied blindfolded participants implicitly learning to perceive their location within environments that were physically encountered via walking on, stepping on, and probing ground surfaces with a cane. Environments were straight-line paths with elevated sections where the path either narrowed or remained the same width. We formed hypotheses concerning how these two environments would affect spatial updating and reorientation processes. In the constant pathwidth environment, homing task accuracy was higher and a manipulation of the elevated surface, to be either unchanged or (unbeknown to participants) shortened, biased the performance. This was consistent with our hypothesis of a metric recalibration scaled to elevated surface extent. In the narrowing pathwidth environment, elevated surface shortening did not bias performance. This supported our hypothesis of positional recalibration resulting from contact with the leading edge of the elevated surface. We discuss why certain environmental properties, such as path-narrowing, have significance for how one becomes implicitly oriented the surrounding environment.

Absence of posture-dependent and posture-congruent memory effects on the recall of action sentences

In two experiments with large samples of participants, we explored contextual memory effects associated with body posture, which was considered a physical and proprioceptive context and, therefore, potentially relevant to the encoding and retrieval of information. In Experiment 1 (N = 128), we studied the effect of context dependence on memory by manipulating the body posture adopted by the participants during the incidental encoding and subsequent recall of a series of action sentences not intrinsically associated with particular body postures (e.g., “to put on a pair of glasses”, “to look at a postcard”). Memory performance was not affected by context manipulation, as reflected by the absence of significant differences between remembering while in the posture adopted at study or in a different posture. Experiment 2 (N = 85) was designed to analyze context congruency memory effects, and for that purpose we manipulated the participants' body posture during the recall of sentences that described actions usually performed in body postures that were congruent or incongruent with the posture of the participants (e.g., recalling the sentence “to travel by taxi” while sitting or while standing). A content-neutral posture (lying) was used for the incidental encoding phase. Memory performance was not affected by contextual congruency at the time of recall, as evidenced by the lack of significant differences between recalling in a posture congruent with the content to be recalled and recalling in an alternative posture. Bayesian analyses supported the strength of null findings in the two experiments, adding to the evidence that, when taken together, the results in this study clearly failed to show contextual memory effects of body posture on the recall of action-related verbal statements.

Blind-Walking Behavior in the Dark Affected by Previewing the Testing Space

Visual environments affect egocentric distance perceptions in full cue conditions. In this study, the effect of three spatial layouts was tested on the perceived location of a self-illuminated single target viewed in the dark. Blind-walking (BW) estimates of target distance were underestimated in all testing spaces, as expected, but foreshortened significantly more in the shortest of the three testing rooms. Additional experiments revealed that neither changes in the perceived angle of declination nor perceived eye height were responsible for this effect. The possibility that subjects made cognitive adjustments to BW behavior to reduce physical risk was assessed by remeasuring target locations in the three different locations with magnitude estimation and by comparing the BW results obtained from subjects who had no preview of the testing space with those who had. The results support the conclusion that the effect of spatial layout is likely due to cognitive adjustments to BW behavior. The results also indicate that the perceived angle of declination is always overestimated by at least a factor of 1.5. These results can be interpreted within the context of a theory of space perception called the angular expansion theory (AET).

The accuracy of the frontal extent in stereoscopic environments: A comparison of direct selection and virtual cursor techniques

This experiment investigated the accuracy of distance judgment and perception of the frontal extent in a stereoscopic environment. Eight virtual targets were projected in a circular arrangement with two center-to-center target distances (18 cm and 36 cm) and three target sizes (0.6 cm, 1.5 cm, and 3.7 cm). Fourteen participants judged the positions of virtual targets presented at a distance of 90 cm from them by employing two different interaction techniques: the direct selection technique and the virtual cursor technique. The results showed overall higher accuracy with the virtual cursor technique than with the direct selection technique. It was also found that the target size significantly affected the frontal extent accuracy. In addition, significant interactions between technique and center-to-center target distance were observed. The direct selection technique was more accurate at the 18 cm center-to-center target distance along the horizontal (x) and vertical (y) axes, while the virtual cursor technique was more accurate for the 36 cm center-to-center target distance along the y axis. During the direct selection, estimations tended to converge to the center of the virtual space; however, this convergence was not observed in the virtual cursor condition. The accuracy of pointing estimations suffered on the left side of participants. These findings could provide direction for virtual reality developers in selecting proper interaction techniques and appropriately positioning virtual targets in stereoscopic environments.

Investigating the Influence of Virtual Human Entourage Elements on Distance Judgments in Virtual Architectural Interiors

Architectural design drawings commonly include entourage elements: accessory objects, such as people, plants, furniture, etc., that can help to provide a sense of the scale of the depicted structure and “bring the drawings to life” by illustrating typical usage scenarios. In this paper, we describe two experiments that explore the extent to which adding a photo-realistic, three-dimensional model of a familiar person as an entourage element in a virtual architectural model might help to address the classical problem of distance underestimation in these environments. In our first experiment, we found no significant differences in participants' distance perception accuracy in a semi-realistic virtual hallway model in the presence of a static or animated figure of a familiar virtual human, compared to their perception of distances in a hallway model in which no virtual human appeared. In our second experiment, we found no significant differences in distance estimation accuracy in a virtual environment in the presence of a moderately larger-than-life or smaller-than-life virtual human entourage model than when a right-sized virtual human model was used. The results of these two experiments suggest that virtual human entourage has limited potential to influence peoples' sense of the scale of an indoor space, and that simply adding entourage, even including an exact-scale model of a familiar person, will not, on its own, directly evoke more accurate egocentric distance judgments in VR.

The role of top-down knowledge about environmental context in egocentric distance judgments

Judgments of egocentric distances in well-lit natural environments can differ substantially in indoor versus outdoor contexts. Visual cues (e.g., linear perspective, texture gradients) no doubt play a strong role in context-dependent judgments when cues are abundant. Here we investigated a possible top-down influence on distance judgments that might play a unique role under conditions of perceptual uncertainty: assumptions or knowledge that one is indoors or outdoors. We presented targets in a large outdoor field and in an indoor classroom. To control visual distance and depth cues between the environments, we restricted the field of view by using a 14-deg aperture. Evidence of context effects depended on the response mode: Blindfolded-walking responses were systematically shorter indoors than outdoors, whereas verbal and size gesture judgments showed no context effects. These results suggest that top-down knowledge about the environmental context does not strongly influence visually perceived egocentric distance. However, this knowledge can operate as an output-level bias, such that blindfolded-walking responses are shorter when observers' top-down knowledge indicates that they are indoors and when the size of the room is uncertain.

Relationship Between Auditory Context and Visual Distance Perception: Effect of Musical Expertise in the Ability to Translate Reverberation Cues Into Room-Size Perception

In a recently published work by our group [ Scientific Reports, 7, 7189 (2017)], we performed experiments of visual distance perception in two dark rooms with extremely different reverberation times: one anechoic ( T ∼ 0.12 s) and the other reverberant ( T ∼ 4 s). The perceived distance of the targets was systematically greater in the reverberant room when contrasted to the anechoic chamber. Participants also provided auditorily perceived room-size ratings which were greater for the reverberant room. Our hypothesis was that distance estimates are affected by room size, resulting in farther responses for the room perceived larger. Of much importance to the task was the subjects' ability to infer room size from reverberation. In this article, we report a postanalysis showing that participants having musical expertise were better able to extract and translate reverberation cues into room-size information than nonmusicians. However, the degree to which musical expertise affects visual distance estimates remains unclear.

Going the distance and beyond: simulated low vision increases perception of distance traveled during locomotion

In a series of experiments, we tested the hypothesis that severely degraded viewing conditions during locomotion distort the perception of distance traveled. Some research suggests that there is little-to-no systematic error in perceiving closer distances from a static viewpoint with severely degraded acuity and contrast sensitivity (which we will refer to as blur). However, several related areas of research-extending across domains of perception, attention, and spatial learning-suggest that degraded acuity and contrast sensitivity would affect estimates of distance traveled during locomotion. In a first experiment, we measured estimations of distance traveled in a real-world locomotion task and found that distances were overestimated with blur compared to normal vision using two measures: verbal reports and visual matching (Experiments 1 a, b, and c). In Experiment 2, participants indicated their estimate of the length of a previously traveled path by actively walking an equivalent distance in a viewing condition that either matched their initial path (e.g., blur/blur) or did not match (e.g., blur/normal). Overestimation in blur was found only when participants learned the path in blur and made estimates in normal vision (not in matched blur learning/judgment trials), further suggesting a reliance on dynamic visual information in estimates of distance traveled. In Experiment 3, we found evidence that perception of speed is similarly affected by the blur vision condition, showing an overestimation in perception of speed experienced in wheelchair locomotion during blur compared to normal vision. Taken together, our results demonstrate that severely degraded acuity and contrast sensitivity may increase people's tendency to overestimate perception of distance traveled, perhaps because of an increased perception of speed of self-motion.

Optical illusions and life-threatening traffic crashes: A perspective on aerial perspective

Aerial perspective illusion is a feature of visual perception where landscapes appear relatively close in clear light and distant in dim light. We hypothesized that bright sunlight might cause drivers to perceive distant terrain as relatively close and misinterpret the approach speed of surrounding landscape as unduly slow. This hypothesis would mean, in turn, that drivers in bright sunlight may underestimate their progress on the road, compensate by traveling at a faster baseline speed, and ultimately increase the prevailing risk of a life-threatening traffic crash. We conducted three pilot studies to illustrate how the illusion might contribute to a life- threatening traffic crash. The first illustration used a questionnaire to demonstrate that most respondents were mistaken when judging the distance between simple balls in different positions. The second illustration involved an experimental manipulation to assess whether aerial perspective influenced judgments about the relative positions of vehicles in traffic. The third illustration analyzed a segment of high-volume fast-speed traffic and found an increased frequency of speeding under bright sunlight. Together with past work based on the visual arts, these examples illustrate how an aerial perspective illusion can affect distance perception, may appear in realistic traffic situations, and could potentially contribute to the risk of a life-threatening traffic crash. An awareness of this hypothesis might lead to applications on how optical illusions could extend to everyday traffic and might potentially inform safety warnings to prevent life- threatening crashes.

Auditory environmental context affects visual distance perception

In this article, we show that visual distance perception (VDP) is influenced by the auditory environmental context through reverberation-related cues. We performed two VDP experiments in two dark rooms with extremely different reverberation times: an anechoic chamber and a reverberant room. Subjects assigned to the reverberant room perceived the targets farther than subjects assigned to the anechoic chamber. Also, we found a positive correlation between the maximum perceived distance and the auditorily perceived room size. We next performed a second experiment in which the same subjects of Experiment 1 were interchanged between rooms. We found that subjects preserved the responses from the previous experiment provided they were compatible with the present perception of the environment; if not, perceived distance was biased towards the auditorily perceived boundaries of the room. Results of both experiments show that the auditory environment can influence VDP, presumably through reverberation cues related to the perception of room size.

The Roles for Prior Visual Experience and Age on the Extraction of Egocentric Distance

OBJECTIVES

In a well-lit room, observers can generate well-constrained estimates of the distance to an object on the floor even with just a fleeting glimpse. Performance under these conditions is typically characterized by some underestimation but improves when observers have previewed the room. Such evidence suggests that information extracted from longer durations may be stored to contribute to the perception of distance at limited time frames. Here, we examined the possibility that this stored information is used differentially across age. Specifically, we posited that older adults would rely more than younger adults on information gathered and stored at longer glimpses to judge the distance of briefly glimpsed objects.

METHOD

We collected distance judgments from younger and older adults after brief target glimpses. Half of the participants were provided 20-s previews of the testing room in advance; the other half received no preview.

RESULTS

Performance benefits were observed for all individuals with prior visual experience, and these were moderately more pronounced for the older adults.

DISCUSSION

The results suggest that observers store contextual information gained from longer viewing durations to aid in the perception of distance at brief glimpses, and that this memory becomes more important with age.

Action potential influences spatial perception: Evidence for genuine top-down effects on perception

The action-specific account of spatial perception asserts that a perceiver's ability to perform an action, such as hitting a softball or walking up a hill, impacts the visual perception of the target object. Although much evidence is consistent with this claim, the evidence has been challenged as to whether perception is truly impacted, as opposed to the responses themselves. These challenges have recently been organized as six pitfalls that provide a framework with which to evaluate the empirical evidence. Four case studies of action-specific effects are offered as evidence that meets the framework's high bar, and thus that demonstrates genuine perceptual effects. That action influences spatial perception is evidence that perceptual and action-related processes are intricately and bidirectionally linked.

Performance environment and nested task constraints influence long jump approach run: a preliminary study

The purpose of the study was to investigate possible changes at step pattern and technical performance of the long jump approach run in seven young long jumpers by modifying the performance environment (long jump runway versus track lane) and the nested actions (run-through with take-off versus complete long jump). Our findings suggest that the step pattern and technical aspects of the approach run are affected by environmental context and nested task constraints. In terms of environmental context, it appears that practising the training routine of run-through followed by take-off on the long jump runway allows athletes to simulate competition conditions in terms of step regulation and technical efficacy. The task of run-through followed by take-off on the track lane failed to initiate visual perception, step regulation and technical efficiency at the steps preceding the instant of take-off. In terms of nested task constraints, when run-ups were followed by jump for distance instead of only a take-off, a higher level of consistency was achieved and step regulation was based on perception-action coupling. Practising long jump run-up accuracy at a setting not containing the informational elements of the performance environment fails to develop the key elements of the skill.

There or not there? A multidisciplinary review and research agenda on the impact of transparent barriers on human perception, action, and social behavior

Through advances in production and treatment technologies, transparent glass has become an increasingly versatile material and a global hallmark of modern architecture. In the shape of invisible barriers, it defines spaces while simultaneously shaping their lighting, noise, and climate conditions. Despite these unique architectural qualities, little is known regarding the human experience with glass barriers. Is a material that has been described as being simultaneously there and not there from an architectural perspective, actually there and/or not there from perceptual, behavioral, and social points of view? In this article, we review systematic observations and experimental studies that explore the impact of transparent barriers on human cognition and action. In doing so, the importance of empirical and multidisciplinary approaches to inform the use of glass in contemporary architecture is highlighted and key questions for future inquiry are identified.

Frontal extents in virtual environments are not immune to underperception

Distance is commonly underperceived by up to 50 % in virtual environments (VEs), in contrast to relatively accurate real world judgments. Experiments reported by Geuss, Stefanucci, Creem-Regehr, and Thompson (Journal of Experimental Psychology: Human Perception and Performance, 38, 1242-1253, 2012) indicate that the exocentric distance separating two objects in a VE is underperceived when the objects are oriented in the sagittal plane (depth extents), but veridically perceived when oriented in a frontoparallel plane (frontal extents). The authors conclude that "distance underestimation in the [VE] generalizes to intervals in the depth plane, but not to intervals in the frontal plane." The current experiment evaluated an alternative hypothesis that the accurate judgments of frontal extents reported by Geuss et al. were due to a fortunate balance of underperception caused by the VE and overperception of frontal relative to depth extents. Participants judged frontal and depth extents in the classroom VE used by Geuss et al. and in a sparser VE containing only a grass-covered ground plane. Judgments in the classroom VE replicated findings by Geuss et al., but judgments in the grass VE show underperception of both depth and frontal extents, indicating that frontal extents are not immune to underperception in VEs.

The Effects of Age and Set Size on the Fast Extraction of Egocentric Distance

Angular direction is a source of information about the distance to floor-level objects that can be extracted from brief glimpses (near one's threshold for detection). Age and set size are two factors known to impact the viewing time needed to directionally localize an object, and these were posited to similarly govern the extraction of distance. The question here was whether viewing durations sufficient to support object detection (controlled for age and set size) would also be sufficient to support well-constrained judgments of distance. Regardless of viewing duration, distance judgments were more accurate (less biased towards underestimation) when multiple potential targets were presented, suggesting that the relative angular declinations between the objects are an additional source of useful information. Distance judgments were more precise with additional viewing time, but the benefit did not depend on set size and accuracy did not improve with longer viewing durations. The overall pattern suggests that distance can be efficiently derived from direction for floor-level objects. Controlling for age-related differences in the viewing time needed to support detection was sufficient to support distal localization but only when brief and longer glimpse trials were interspersed. Information extracted from longer glimpse trials presumably supported performance on subsequent trials when viewing time was more limited. This outcome suggests a particularly important role for prior visual experience in distance judgments for older observers.

Neural extrapolation of motion for a ball rolling down an inclined plane

It is known that humans tend to misjudge the kinematics of a target rolling down an inclined plane. Because visuomotor responses are often more accurate and less prone to perceptual illusions than cognitive judgments, we asked the question of how rolling motion is extrapolated for manual interception or drawing tasks. In three experiments a ball rolled down an incline with kinematics that differed as a function of the starting position (4 different positions) and slope (30°, 45° or 60°). In Experiment 1, participants had to punch the ball as it fell off the incline. In Experiment 2, the ball rolled down the incline but was stopped at the end; participants were asked to imagine that the ball kept moving and to punch it. In Experiment 3, the ball rolled down the incline and was stopped at the end; participants were asked to draw with the hand in air the trajectory that would be described by the ball if it kept moving. We found that performance was most accurate when motion of the ball was visible until interception and haptic feedback of hand-ball contact was available (Experiment 1). However, even when participants punched an imaginary moving ball (Experiment 2) or drew in air the imaginary trajectory (Experiment 3), they were able to extrapolate to some extent global aspects of the target motion, including its path, speed and arrival time. We argue that the path and kinematics of a ball rolling down an incline can be extrapolated surprisingly well by the brain using both visual information and internal models of target motion.

The underestimation of egocentric distance: evidence from frontal matching tasks

There is controversy over the existence, nature, and cause of error in egocentric distance judgments. One proposal is that the systematic biases often found in explicit judgments of egocentric distance along the ground may be related to recently observed biases in the perceived declination of gaze (Durgin & Li, Attention, Perception, & Psychophysics, in press), To measure perceived egocentric distance nonverbally, observers in a field were asked to position themselves so that their distance from one of two experimenters was equal to the frontal distance between the experimenters. Observers placed themselves too far away, consistent with egocentric distance underestimation. A similar experiment was conducted with vertical frontal extents. Both experiments were replicated in panoramic virtual reality. Perceived egocentric distance was quantitatively consistent with angular bias in perceived gaze declination (1.5 gain). Finally, an exocentric distance-matching task was contrasted with a variant of the egocentric matching task. The egocentric matching data approximate a constant compression of perceived egocentric distance with a power function exponent of nearly 1; exocentric matches had an exponent of about 0.67. The divergent pattern between egocentric and exocentric matches suggests that they depend on different visual cues.

Contextual effects on perceived three-dimensional shape

Binocular disparity is a powerful cue for the perception of depth. The accuracy with which observers can judge depth from disparity can, however, be very poor. This has been attributed to difficulties associated with the scaling of disparity to take account of distance (Johnston, 1991). We test potential strategies that could be used to improve this scaling. Using the depth-to-width ratio task introduced by Bradshaw, Parton, and Eagle (1998), observers adjusted a depth interval to match the vertical distance between two points. The first experiment examined the effect of placing additional visual stimuli between the observer and the target. Despite the potential of these stimuli to provide reliable distance information, the accuracy of depth settings did not change. The second experiment demonstrated that the degree of binocular correlation present in natural images provides useful distance information, and investigated whether this is used by observers in scaling disparity. To do this, we measured whether varying the magnitude of relative disparity presented in the surround of the target affected depth settings. No such effect was observed. We conclude that the effect of information presented in the surrounding context on settings of depth is limited to those situations in which it provides direct information about the distance to the target.

Revisiting the effect of quality of graphics on distance judgments in virtual environments: a comparison of verbal reports and blind walking

In immersive virtual environments, judgments of perceived egocentric distance are significantly underestimated, as compared with accurate performance in the real world. Two experiments assessed the influence of graphics quality on two distinct estimates of distance, a visually directed walking task and verbal reports. Experiment 1 demonstrated a similar underestimation of distances walked to previously viewed targets in both low- and high-quality virtual classrooms. In Experiment 2, participants' verbal judgments underestimated target distances in both graphics quality environments but were more accurate in the high-quality environment, consistent with the subjective impression that high-quality environments seem larger. Contrary to previous results, we suggest that quality of graphics does influence judgments of distance, but only for verbal reports. This behavioral dissociation has implications beyond the context of virtual environments and may reflect a differential use of cues and context for verbal reports and visually directed walking.