Depth cues, such as binocular disparity, play a critical role in supporting accurate and precise reaching within near space, facilitating reliable interaction with objects and surfaces [27]. Augmented reality (AR) presents unique challenges for such interactions, as mismatched focal distances between real and virtual objects can distort perceived depth. Prior work has examined the perceptual consequences of focal distance mismatches under controlled viewing conditions, as well as AR task performance in more natural settings; here we consider these factors together in a visually guided reaching task with multiple available depth cues for combinations of real and virtual objects. Participants performed a precision visual motor task in an AR environment, placing a virtual ring around either real or virtual posts at varying distances. Our results show that accuracy was degraded when placing a virtual ring on real posts, with fewer successful placements compared to virtual posts. We demonstrate that this increase in error was due to a systematic underestimation of virtual object distances relative to their physical counterparts. These findings indicate that distortions in perceived depth between real and virtual objects persist during active reaching, despite the availability of multiple depth cues including binocular disparity, proprioception, occlusion, and motion parallax. Measuring and correcting for these distortions is important for optimizing the effectiveness and usability of AR devices.

Binocular disparity provides metric depth information, while monocular cues like occlusion offer depth order. In augmented reality (AR), conflicts between these cues can occur when virtual objects fail to be occluded by real-world surfaces, creating a depth cue conflict and subsequently impacting depth perception. The integration of occlusion and binocular disparity was investigated under this cue conflict in AR using distance-matching paradigms. These paradigms were applied within reach space (0.35–0.5 m) and beyond reach space (0.9–1.5 m). Observers matched the distance of a virtual letter ’A,’ superimposed on a physical surface, using a virtual probe. In addition to the probe, manual reach responses were also made with the index finger for the within reach space condition. Results revealed consistent underestimation of the letter’s distance when it was rendered beyond the surface, with errors proportional to distance. These biases persisted even when proprioceptive information was available, highlighting the robust influence of occlusion cue conflicts on perceived depth. Thus, designers must carefully plan and position virtual augmentations to avoid such errors and their impact on user interaction.

Virtual reality (VR) often induces perceptual distortions, for instance, underestimates of perceived distance which may distort perceived size. However, other depth cues are available in these immersive environments that may help users perceive size accurately. Here, we examined how binocular and monocular depth cues, as well as object interaction, influenced the perceived size of 3D shapes in VR. The results showed that binocular cues play an essential role in size judgements, whereas dynamic monocular cues, such as motion parallax, did not fully compensate for their absence, underscoring the importance of rendering high-quality binocular cues for fine size discrimination tasks in virtual environments.

Stereoscopic displays present similar but different images/videos separately to the left and right eyes. Here we report the results of a subjective assessment of computer-generated high dynamic range (HDR) stereoscopic video compression targeting lightweight, low-latency visually lossless performance. The ISO/IEC 29170–2 non-flicker paradigm (Annex A) was adapted for stereoscopic videos and used to evaluate the VESA DSC 1.2a and VDC-M 1.2.2 codecs operating at and beyond their recommended maximum compression levels. Both codecs exhibited visually lossless performance at their target compressions levels. There were differences in compression artifact detection rates with some image sequences between stereoscopic and 2D presentation although the direction of the difference was inconsistent. The results confirm the effectiveness of these codecs for Stereoscopic 3D (S3D) videos and suggest that observers are relatively insensitive to compression artifacts in moving stereoscopic imagery.

Virtual reality (VR) is distinguished by the rich, multimodal, im-mersive sensory information and affordances provided to the user. However, when moving about an immersive virtual world the vi-sual display often conflicts with other sensory cues due to design, the nature of the simulation, or to system limitations (for example impoverished vestibular motion cues during acceleration in racing games). Given that conflicts between sensory cues have been as-sociated with disorientation or discomfort, and theoretically could distort spatial perception, it is important that we understand how and when they are manifested in the user experience. To this end, this set of experiments investigates the impact of mismatch between physical and virtual motion parallax on the per-ception of the depth of an apparently perpendicular dihedral angle (a fold) and its distance. We applied gain distortions between visual and kinesthetic head motion during lateral sway movements and measured the effect of gain on depth, distance and lateral space compression. We found that under monocular viewing, observers made smaller object depth and distance settings especially when the gain was greater than 1. Estimates of target distance declined with increasing gain under monocular viewing. Similarly, mean set depth decreased with increasing gain under monocular viewing, except at 6.0 m. The effect of gain was minimal when observers viewed the stimulus binocularly. Further, binocular viewing (stereopsis) improved the precision but not necessarily the accuracy of gain perception. Overall, the lateral compression of space was similar in the stereoscopic and monocular test conditions. Taken together, our results show that the use of large presentation distances (at 6 m) combined with binocular cues to depth and distance enhanced humans' tolerance to visual and kinesthetic mismatch.

Stereoscopic AR and VR headsets have displays and lenses that are either fixed or adjustable to match a limited range of user inter-pupillary distances (IPDs). Projective geometry predicts a misperception of depth when either the displays or virtual cameras used to render images are misaligned with the eyes. However, misalignment between the eyes and lenses might also affect binocular convergence, which could further distort perceived depth. This possibility has been largely ignored in previous studies. Here, we evaluated this phenomenon in a VR headset in which the inter-lens and inter-axial camera separations are coupled and adjustable. In a baseline condition, both were matched to observers' IPDs. In two other conditions, the inter-lens and inter-axial camera separations were set to the maximum and minimum allowed by the headset. In each condition, observers were instructed to adjust a fold created by two intersecting, textured surfaces until it appeared to have an angle of 90°. The task was performed at three randomly interleaved viewing distances, monocularly and binocularly. In the monocular condition, observers underestimated the fold angle and there was no effect of viewing distance on their settings. In the binocular conditions, we found that when the lens and camera separation were less than the viewer's IPD, they exhibited compression of perceived slant relative to baseline. The reverse pattern was seen when the lens and camera separation were larger than the viewer's IPD. These results were well explained by a geometric model that considers shifts in convergence due to lens and display misalignment with the eyes, as well as the relative contribution of monocular cues.

The magnifying optics of virtual reality (VR) head-mounted displays (HMD) often cause undesirable pincushion distortion in the displayed imagery. Eccentrically increasing magnification radially displaces image-points away from the optical axis, causing straight lines to curve outwards. This, in turn, should affect the 3D perception of surface shape by warping binocular and monocular depth cues. Previous research has shown that distortion-induced biases in perceived slant do occur in static images. However, most use cases in VR involve moving images. Here we evaluate the impact of motion on biases in perceived slant. An HMD was used to present flat, textured surfaces that varied in slant and were either stationary, or translated laterally by the observer. In separate studies we varied the degree of distortion and evaluated the impact on perceived slant at several locations along the surface. We found that, irrespective of whether the surface was moving or stationary, distortion introduced significant bias into local slant estimates. The pattern of results is consistent with the surface appearing to be concave (as if viewing the inside surface of a bowl), as predicted from the warping of binocular and monocular cues. Importantly, the intermediate distortion level produced the same, but weaker, pattern of biases seen in the fully-distorted condition. When an appropriate level of pre-warping was applied, slant perception was veridical. Overall, our results highlight the importance of sufficiently correcting for optical distortions in VR HMDs to enable veridical perception of surface attitude.

In stereoscopic displays different images are presented separately to the left and right eyes. This requirement may increase the bandwidth demand as well as increase the occurrence of visible compression-related artefacts. Here we report the results of a large-scale subjective assessment of high dynamic range (HDR) stereoscopic image compression. The ISO/IEC 29170-2 flicker paradigm was adapted for stereoscopic images and used to evaluate two VESA (Video Electronics Standards Association) image compression codecs: DSC 1.2a and VDCM 1.2.2. We compared the performance on stereoscopic images versus 2D images for both codecs.

This paper describes validity testing of the NeuLog NUL-217 GSR measurement device. This was accomplished by comparing the NeuLog device to readings from the Biopac Student Lab Systems EDA system. The results of this research found that measurements from the NeuLog device are correlated with and comparable to the Biopac system. The absolute skin conductance levels typically differed between the two systems. For most psychological and human factors research the dynamic skin conductance responses are more important than absolute levels. The timing and relative magnitude of changes typically tracked well across the two systems indicating that the Neulog system is suitable for the purposes of its intended use in psychological and technological research.

There is growing interest in capturing and projecting movies at higher frame rates than the traditional 24 frames per second. Yet there has been little scientific assessment of the impact of higher frame rates (HFR) on the perceived quality of cinema content. Here we investigated the effect of frame rate, and associated variables (shutter angle and camera motion) on viewers' ability to discriminate letters in S3D movie clips captured by a professional film crew. The footage was filmed and projected at varying combinations of frame rate, camera speed and shutter angle. Our results showed that, overall, legibility improved with increased frame rate and reduced camera velocity. However, contrary to expectations, there was little effect of shutter angle on legibility. We also show that specific combinations of camera parameters can lead to dramatic reductions in legibility for localized regions in a scene.

An intriguing aspect of picture perception is the viewer’s tolerance to variation in viewing position, perspective, and display size. These factors are also present in stereoscopic media, where there are additional parameters associated with the camera arrangement (e.g., separation, orientation). The predicted amount of depth from disparity can be obtained trigonometrically; however, perceived depth in complex scenes often differs from geometric predictions based on binocular disparity alone. To evaluate the extent and the cause of deviations from geometric predictions of depth from disparity in naturalistic scenes, we recorded stereoscopic footage of an indoor scene with a range of camera separations (camera interaxial (IA) ranged from 3 to 95 mm) and displayed them on a range of screen sizes. In a series of experiments participants estimated 3D distances in the scene relative to a reference scene, compared depth between shots with different parameters, or reproduced the depth between pairs of objects in the scene using reaching or blind walking. The effects of IA and screen size were consistently and markedly smaller than predicted from the binocular viewing geometry, suggesting that observers are able to compensate for the predicted distortions. We conclude that the presence of multiple realistic monocular depth cues drives normalization of perceived depth from binocular disparity. It is not clear to what extent these differences are due to cognitive as opposed to perceptual factors. However, it is notable that these normalization processes are not task specific; they are evident in both perception- and action-oriented tasks.

High frame-rate (HFR) movie-making refers to the capture and projection of movies at frame rates several times higher than the traditional 24 frames per second. This higher frame rate theoretically improves the quality of motion portrayed in movies, and helps avoid motion blur, judder, and other undesirable artifacts. However, there is considerable debate in the cinema industry regarding the acceptance of HFR content given anecdotal reports of hyper-realistic imagery that reveals too much set and costume detail. Despite the potential theoretical advantages, there has been little empirical investigation of the impact of high frame-rate techniques on the viewer experience. In this study, we use stereoscopic 3D content, filmed and projected at multiple frame rates (24, 48, and 60 fps), with shutter angles ranging from 180° to 358°, to evaluate viewer preferences. In a paired-comparison paradigm, we assessed preferences along a set of five attributes (realism, motion smoothness, blur/clarity, quality of depth, and overall preference). The resulting data show a clear preference for higher frame rates, particularly when contrasting 24 fps with 48 or 60 fps. We found little impact of shutter angle on viewers' choices, with the exception of one measure (motion smoothness) for one clip type. These data are the first empirical evidence of the advantages afforded by high frame-rate capture and presentation in a cinema context.

Stereoscopic 3D media has recently increased in appreciation and availability. This popularity has led to concerns over the health effects of habitual viewing of stereoscopic 3D content; concerns that are largely hypothetical. Here we examine the effects of repeated, long-term exposure to stereoscopic 3D in the workplace on several measures of stereoscopic sensitivity (discrimination, depth matching, and fusion limits) along with reported negative symptoms associated with viewing stereoscopic 3D. We recruited a group of adult stereoscopic 3D industry experts and compared their performance with observers who were (i) inexperienced with stereoscopic 3D, (ii) researchers who study stereopsis, and (iii) vision researchers with little or no experimental stereoscopic experience. Unexpectedly, we found very little difference between the four groups on all but the depth discrimination task, and the differences that did occur appear to reflect task-specific training or experience. Thus, we found no positive or negative consequences of repeated and extended exposure to stereoscopic 3D in these populations.

The perception of synchronous, intelligible, speech is fundamental to a high-quality modern cinema experience. Surprisingly, this issue has remained relatively unexplored in stereoscopic 3D (S3D) media, despite its increasing popularity. Instead, visual parameters have been the primary focus of concern for those who create, and those who study the impact of, S3D content. In the work presented here we ask if ability to integrate audio and visual information is influenced by adding the third dimension to film. We also investigate the effects of known visual parameters (horizontal and vertical parallax), on audio-visual integration. To this end, we use an illusion of speech processing known as the McGurk effect as an objective measure of multi-modal integration. In the classic (2D) version of this phenomenon, discrepant auditory (/ba/) and visual (/ga/) information typically results in the perception of a unique 'fusion' syllable (e.g. /da/). We extended this paradigm to measure the McGurk effect in a small theatre. We varied the horizontal (IA: 0, 6, 12, 18, 24 mm) and vertical (0°, 0.5°, 0.75°, 1°) parallax from trial-to-trial and asked observers to report their percept of the phoneme. Our results show a consistently high proportion of the expected fusion responses, with no effect of horizontal or vertical offsets. These data are the first to show that the McGurk effect extends to stereoscopic stimuli and is not a phenomenon isolated to 2D media perception. Furthermore, the results show that audiences can tolerate a high level of both horizontal and vertical disparity and maintain veridical speech perception. We consider these results in terms of current stereoscopic filmmaking recommendations and practices.

Improving the sense of “presence” is a common goal of three-dimensional (3D) display technology for film, television, and virtual reality. However, there are instances in which 3D presentations may elicit unanticipated negative responses. For example, it is well established that violations of interpersonal space cause discomfort in real-world situations. Here we ask if people respond similarly when viewing life-sized stereoscopic images. Observers rated their level of comfort in response to animate and inanimate objects in live and virtual (stereoscopic projection) viewing conditions. Electrodermal activity was also recorded to monitor their physiological response to these stimuli. Observers exhibited significant negative reactions to violations of interpersonal space in stereoscopic 3D displays, which were equivalent to those experienced in the natural environment. These data have important implications for the creation of 3D media and the use of virtual reality systems.