Focus Cues Research Articles

Perception of post-focus compression as a cue to focus in L2 English

English and Mandarin both mark focus with post-focus compression (PFC) of F0 and intensity. Previous production research indicates PFC may be a universally marked feature difficult to transfer between languages, but the generally narrower pitch range and lack of fluency indicative of nonnative speech impede the ability to conclude the marked status of PFC based on production data alone. The present study utilized accuracy scores on a forced-choice prosodic restoration perception task to identify whether nonnative learners of a PFC language (English) with a native PFC language L1 (Mandarin) are capable of perceiving PFC as a cue to focus when no other focus cues are available. The role of L2 proficiency in the ability to use PFC as a cue to focus was also examined. Results indicate that native Mandarin listeners had significantly poorer accuracy compared to native English listeners at using PFC as a cue to focus in English regardless of proficiency, thus supporting PFC’s role as a marked feature not easily transferred into an L2, but some Mandarin listeners’ above chance performance on the task indicate it is not impossible to perceive PFC as a cue to focus in an L2 context.

Reflections from expert throws coaches on the use of attentional focus cues during training

BACKGROUND: Previous research in motor learning shows that adopting an external focus of attention significantly benefits performance and learning among novice participants. Research has been fairly limited in regards to the attentional focus reported to be used by highly skilled performers or coaches. Fairbrother et al. (2016) suggested that experts might utilize more complex attentional strategies than a simple dyad of internal or external foci. AIM: The purpose of the present study was to examine attentional focus cues utilized by elite track and field throws coaches during practice and competition. METHOD: Fifteen NCAA track and field coaches completed a questionnaire related the instructions they provide their athletes during practice. Meaning units that related to attentional focus were extracted from the questionnaires and categorized into associative and dissociative cues. The cues were then categorized for various attentional focus strategies. RESULTS: Results showed that elite coaches utilized multiple attentional focus strategies which included internal, external, and holistic focus cues. The most common attentional focus utilized with collegiate throwers was that of a holistic focus, which directs attention to the general feeling of the movement (Becker et al. 2019). It was observed that elite throws coaches alter their focus of attention instruction based on their unique style of coaching and the perceived needs of the athlete. CONCLUSION: This research shows that attentional focus is not as simple as adopting one focus strategy for all individuals within all contexts.

Utilising an internal focus of attention during preparation and an external focus during execution may facilitate motor learning

ABSTRACT Research with athletes and coaches has found that attentional focus strategies are more complex than using an internal or external focus exclusively. Recently Becker et al. [2020, March 1. The effects of attentional focus in the preparation and execution of a standing long jump. Psychological Research, 84(2), 285–291] found that switching attentional focus from internal in movement preparation to external during movement execution provided a benefit over internal focus and control conditions. The purpose of this study was to investigate the effects of attentional switching on motor skill acquisition. 79 participants were randomly divided into an internal (INT), external (EXT), or switching group (IES). Individuals performed 80 acquisition trials of a golf chipping task with their prescribed attentional focus during preparation and execution. 24-hours later 10-trial retention and transfer tests were performed. The primary analysis revealed significant improvement during acquisition (p < .001) but no significant differences between attentional focus groups during acquisition, retention, or transfer. A secondary analysis was performed with individuals low in attentional focus adherence removed (<60%). Groups significantly improved during acquisition (p < .001). For retention IES significantly outperformed INT (p < .05). These results suggest that the detrimental effects of an internal focus are only found during skill execution and not movement preparation. It is possible for learners to benefit from both an internal and external focus so long as the cues are provided during the correct phase of skill performance. Highlights Attentional focus is much more complex than using either an internal or external focus of attention. This study investigated the effects of switching attention during skill acquisition from an internal to external focus. A preliminary analysis revealed no significant differences between attentional focus groups of internal, external, or switching. One reason for this finding was the poor adherence to the prescribed focus cue. A secondary analysis where low adherence individuals were removed revealed a significant difference between the switching group and the internal focus group during retention. These finding suggest that the detrimental effects associated with an internal focus of attention are exclusive to using the focus during task execution. It is possible that an internal focus can still facilitate learning so long as an external focus is used during movement execution.

Holographic techniques for augmented reality and virtual reality near-eye displays

Near-eye displays are the main platform devices for many augmented reality (AR) and virtual reality (VR) applications. As a wearable device, a near-eye display should have a compact form factor and be lightweight. Furthermore, a large field of view and sufficient eyebox are crucial for immersive viewing conditions. Natural three-dimensional (3D) image presentation with proper focus cues is another requirement that enables a comfortable viewing experience and natural user interaction. Finally, in the case of AR, the device should allow for an optical see-through view of the real world. Conventional bulk optics and two-dimensional display panels exhibit clear limitations when implementing these requirements. Holographic techniques have been applied to near-eye displays in various aspects to overcome the limitations of conventional optics. The wavefront reconstruction capability of holographic techniques has been extensively exploited to develop optical see-through 3D holographic near-eye displays of glass-like form factors. In this article, the application of holographic techniques to AR and VR near-eye displays is reviewed. Various applications are introduced, such as static holographic optical components and dynamic holographic display devices. Current issues and recent progress are also reviewed, providing a comprehensive overview of holographic techniques that are applied to AR and VR near-eye displays.

Effects of an expert-modeled attentional focus cue structure on skilled jump rope performance and learning.

Instructions that direct attention externally have been shown to enhance motor performance. However, research on skilled performers and on learning effects has produced some distinct findings. Further, many studies have presented an overly simplistic view of attention and learning, such that all-internal focus protocols are contrasted with all-external focus protocols. Contrary to this approach, skilled performers have reported adopting combined focus strategies, revealing the need to test more realistic instructional protocols. The current study provided an experimental test of focus instructions that were modeled after the strategies of elite jump rope athletes. Four groups of skilled jump rope athletes practiced novel skills under various focus instructions. The internal focus (IF) and external focus (EF) groups were given traditional internal and external focus instructions, respectively. The expert modeled (EM) group was given a set of instructions that were based on experts' reported focus strategies. The expert modeled-autonomous (EM-A) group was allowed to choose how they used each of the expert-modeled instructions. All groups completed a baseline assessment, four practice sessions, and a learning assessment. Results of a chi-square test of independence revealed no relationship between group assignment and performance during baseline or practice. There was a significant relationship between group assignment and performance during the learning assessment (p<.05). Specifically, the IF group performed below expected values while the EM group performed better than expected. Findings support previous research showing learning detriments associated with internal focus instructions and also provide new insight into the advantages of using instructional approaches that are modeled after experts' strategies. Implications and suggestions for future research are discussed.

Multifocal Stereoscopic Projection Mapping.

Stereoscopic projection mapping (PM) allows a user to see a three-dimensional (3D) computer-generated (CG) object floating over physical surfaces of arbitrary shapes around us using projected imagery. However, the current stereoscopic PM technology only satisfies binocular cues and is not capable of providing correct focus cues, which causes a vergence-accommodation conflict (VAC). Therefore, we propose a multifocal approach to mitigate VAC in stereoscopic PM. Our primary technical contribution is to attach electrically focus-tunable lenses (ETLs) to active shutter glasses to control both vergence and accommodation. Specifically, we apply fast and periodical focal sweeps to the ETLs, which causes the "virtual image" (as an optical term) of a scene observed through the ETLs to move back and forth during each sweep period. A 3D CG object is projected from a synchronized high-speed projector only when the virtual image of the projected imagery is located at a desired distance. This provides an observer with the correct focus cues required. In this study, we solve three technical issues that are unique to stereoscopic PM: (1) The 3D CG object is displayed on non-planar and even moving surfaces; (2) the physical surfaces need to be shown without the focus modulation; (3) the shutter glasses additionally need to be synchronized with the ETLs and the projector. We also develop a novel compensation technique to deal with the "lens breathing" artifact that varies the retinal size of the virtual image through focal length modulation. Further, using a proof-of-concept prototype, we demonstrate that our technique can present the virtual image of a target 3D CG object at the correct depth. Finally, we validate the advantage provided by our technique by comparing it with conventional stereoscopic PM using a user study on a depth-matching task.

Foveated light-field display and real-time rendering for virtual reality.

Glasses-free light field displays have significantly progressed due to advances in high-resolution microdisplays and high-end graphics processing units (GPUs). However, for near-eye light-field displays requiring portability, the fundamental trade-off regarding achieved spatial resolution remains: retinal blur quality must be degraded; otherwise, computational consumption increases. This has prevented synthesizing the high-quality light field from being fast. By integrating off-the-shelf gaze tracking modules into near-eye light-field displays, we present wearable virtual reality prototypes supporting human visual system-oriented focus cues. An optimized, foveated light field is delivered to each eye subject to the gaze point, providing more natural visual experiences than state-of-the-art solutions. Importantly, the factorization runtime can be immensely reduced, since the image resolution is only high within the gaze cone. In addition, we demonstrate significant improvements in computation and retinal blur quality over counterpart near-eye displays.

When virtual and real worlds coexist: Visualization and visual system affect spatial performance in augmented reality.

New visualization approaches are being actively developed aiming to mitigate the effect of vergence-accommodation conflict in stereoscopic augmented reality; however, high interindividual variability in spatial performance makes it difficult to predict user gain. To address this issue, we investigated the effects of consistent and inconsistent binocular and focus cues on perceptual matching in the stereoscopic environment of augmented reality using a head-mounted display that was driven in multifocal and single focal plane modes. Participants matched the distance of a real object with images projected at three viewing distances, concordant with the display focal planes when driven in the multifocal mode. As a result, consistency of depth cues facilitated faster perceptual judgments on spatial relations. Moreover, the individuals with mild binocular and accommodative disorders benefited from the visualization of information on the focal planes corresponding to image planes more than individuals with normal vision, which was reflected in performance accuracy. Because symptoms and complaints may be absent when the functionality of the sensorimotor system is reduced, the results indicate the need for a detailed assessment of visual functions in research on spatial performance. This study highlights that the development of a visualization system that reduces visual stress and improves user performance should be a priority for the successful implementation of augmented reality displays.

Attentional Focus and Individuals’ Perceptions: A Systematic Review

Although multiple review studies have supported the superior effects of an external compared with internal focus, these reviews are based on performance outcomes. Currently, the literature lacks knowledge regarding the effects of external/internal foci on individuals’ perceptions, which may provide further explanations for how attentional focus affects performance. Therefore, the present study conducted a systematic review of survey/questionnaire data of participants’ thoughts and emotions from laboratory studies. The authors used ERIC, SPORTDiscus, PsycArticle, CINAHL Plus, Health Source Nursing Academic edition, and PubMed search engines. Literature specific to external/internal focus effects on motor learning or performance were reviewed (N = 37). The results showed that participants generally adhered to the assigned attentional focus instruction and there was a trend that preference may affect the attentional focus effects, but the results were inconsistent regarding if attentional focus cues affected the magnitude of adherence and mental demands. There were substantial differences in methodologies and theoretical issues of measuring these data. Future studies should adopt inferential statistics, choose theoretically relevant questions in a priori manner, or, at minimum, propose a hypothesis for the selected question.

Render‐based factorization for additive light field display

AbstractAugmented Reality (AR) and Virtual Reality (VR) applications enable viewers to experience 3D graphics immersively. However, current hardware either fails to provide multiple viewpoints like projectors or cause conflicts between vergence and accommodation like consumable headsets. Prior researchers have designed multi‐view displays to solve the problem by enabling view‐dependent images and focus cues. Nevertheless, it requires minutes to calculate one frame, which is critical for real‐time AR/VR applications. In this paper, we propose a new render‐based factorization for additive light field display and further improve the performance by optimizing the initialization of layers. We next compare our work with the state of the art and the results show that our solution has competitive results while the calculation takes less than 20 ms for each frame.

Extending eyebox with tunable viewpoints for see-through near-eye display.

The Maxwellian display presents always-focused images to the viewer, alleviating the vergence-accommodation conflict (VAC) in near-eye displays (NEDs). However, the limited eyebox of the typical Maxwellian display prevents it from wider applications. We propose a Maxwellian see-through NED based on a multiplexed holographic optical element (HOE) and polarization gratings (PGs) to extend the eyebox by viewpoint multiplication. The multiplexed HOE functions as multiple convex lenses to form multiple viewpoints, which are copied to different locations by PGs. To mitigate the imaging problem that multiple viewpoints or no viewpoints enter the eye pupil, the viewpoints can be tuned by mechanically moving a PG. We implement our method in a proof-of-concept system. The optical experiments confirm that the proposed display system provides always in-focus images within a 12 mm eyebox in the horizontal direction with a 32.7° diagonal field of view (FOV) and a 16.5 mm eye relief (ERF), and its viewpoints are tunable to match the actual eye pupil size. Compared with other techniques to extend the eyebox of Maxwellian displays, the proposed method shows competitive performances of a large eyebox, adaptability to the eye pupil size, and focus cues within a large depth range.

Effects of attentional focus cues on lower extremity kinematics during inside of the foot soccer trap among expert soccer players

Numerous studies have demonstrated improved performance results for sport skills through attentional focus instructions. However, few studies have examined the effects of cueing on expert kinematic performance, and this is the first to assess cueing’s kinematic effects on expert soccer players performing .common techniques This study assessed the lower extremity kinematics of an inside of the foot soccer trap via motion capture cameras under different attentional focus cues to analyze how the cues affect the movement pattern among expert performers. 10 NCAA Division 1 soccer players trapped a launched ball on a scoring mat after receiving coaching cues inducing an internal, external, holistic, or control focus of attention. Statistical analysis revealed movement differences between the internal and external cue conditions for the ankle and knee joints during the movement. The difference at the knee was a steeper flexion followed by a correction and, at the ankle, a steeper flexion, both during the internal cue condition. Attentional focus cues inducing a conscious control of the movement may disrupt the movement patterns of highly skilled expert performers. Coaches should be acutely aware of the language they use in instruction, even among expert performers.

Earnouts in M&amp;A deal structuring: The impact of CEO prevention focus

This empirical study leverages the theoretical underpinnings of regulatory focus theory, an influential theory of self-regulation, to investigate the impact of CEOs' dispositional prevention focus on firms' deal structuring choices in mergers and acquisitions. We build on the argument that the dispositional prevention focus of individuals is associated with a higher perception of risk and a preference for non-losses. Accordingly, this study suggests a positive relationship between the intensity of an acquiring firm CEO's dispositional prevention focus and the firm's propensity to use earnouts as a post-closing risk-mitigating instrument in the deal consideration structure. Furthermore, this study accounts for the important role of contextual cues in priming dispositional prevention focus through the concepts of regulatory fit and misfit and examines the moderating impact of M&A deals involving foreign targets and the acquiring firm's acquisition experience on the baseline relationship. We test our predictions on a dataset comprising 217 deals from 2006 to 2011 in the United Kingdom. Building on the micro-foundations of strategy, these findings contribute to the literature on deal structuring choices in mergers and acquisitions.

Effects of an external focus of attention and target occlusion on performance in virtual reality.

The use of virtual reality as a training mechanism continues to gain popularity as equipment becomes more readily available. It is important to not only understand the relationship between virtual reality training and motor learning, but to understand the extent to which practice manipulations enhance performance in virtual reality. One common practice manipulation is adopting an external focus of attention, which has been shown to facilitate motor learning in a variety tasks. The purposes of the present study were to investigate the effectiveness of an external focus of attention and the effects of target occlusion times in virtual reality. Fifty-six participants performed a single-leg long jump during baseline, training, and retention and were randomly assigned to either an external or control group. During baseline and retention, all participants performed the task in both a virtual reality (VR) and real world (RW) environments. Training was all done in VR where participants were provided an external focus cue or no cue. Results revealed that individuals jumped significantly further in RW than VR in both baseline and retention (p<.001). During training, the external group jumped significantly further than control (p<.05). These results suggest that the adoption of an external focus improves performance during training. However, we did not see a benefit of an external focus in retention. These findings should be taken into consideration when using virtual reality as a training tool when performance must be transferred to a real world environment.

Sampling-Noise Modeling &amp; Removal in Shape From Focus Systems Through Kalman Filter

Shape from Focus (SFF) is one of the passive techniques to recover the shape of an object under consideration. It utilizes the focus cue present in the stack of images, obtained by a single camera. In SFF when the images are acquired, the inter-frame distance, also known as the sampling step size, is assumed to be constant. However, in practice, due to mechanical constraints, sampling step size cannot remain constant. The inconsistency in the sampling step size causes the problem of jitter, and produces Jitter noise in focus curves. This Jitter noise is not visible in images, because each pixel in an image (of the stack) will be subjected to the same error in focus. Thus, traditional image denoising techniques will not work. This paper formulates a model of the Jitter noise, followed by the design of system and measurement models for Kalman filter. Then, the jittering problem for SFF systems is solved using the proposed filtering technique. Experiments are performed on simulated and real objects. Ten noise levels are considered for simulated, and four for real objects. RMSE and Correlation are used to measure the reconstructed shape. The results show the effectiveness of the proposed scheme.

Foveated near-eye display for mixed reality using liquid crystal photonics

Foveated near-eye display is one of the most promising approaches to deliver immersive experience of mixed reality. However, it is challenged to conceive a compact optical system. Here, we introduce a method to use polarization optics via liquid crystal photonics to improve the foveated display performance. We demonstrate a benchtop prototype of this idea. We implement and combine two display modules for peripheral and foveal visions. A peripheral display consists of a polarization selective lens (PSL) module, a polarization selective diffuser (PSD), and a slanted projection system. An 80^circ diagonal field of view is achieved by on-axis optical configuration of the PSL module and the PSD. A foveal holographic display is composed of a spatial light modulator (SLM), a volume grating lens, and a microelectromechanical system mirror possibly in combination with a switchable polarization selective grating module. The holographic reconstruction using the SLM enables accurate focus cue generation and high resolution above 30 cycles per degree within 15^circ by 15^circ field of view. We explore and discuss the liquid crystal photonics in the prototype that has a novel optical design using volume gratings with polarization selectivity.

The Effects of Attentional Focus Instructions Specific to Body Movements on Movement Quality and Performance

To compare the effects of internal and external focus instructions specific to body movements. Mixed design, 2 (sex) × 2 (instructions). Laboratory setting. A total of 40 participants (males, n = 20; mean [SD]; age = 22.0 [2.19]y; height = 179.33 [5.90]cm; mass = 77.7 [13.04]kg; females, n = 20; age = 22.0 [3.87]y; height = 164.84 [5.80]cm; mass = 71.48 [20.66]kg) were recruited. Participants completed 2 consecutive jumps (ie,a forward jump from a height and then a maximal vertical jump) with internal focus and external focus instructions. External focus was elicited by placing pieces of tape on the participants' legs. Landing quality was measured by the Landing Error Scoring System to assess movement quality, and the vertical jump height was measured by Vertec. The performance results showed that the external focus condition resulted in superior vertical jump height compared with the internal focus condition (P < .05). Although landing quality did not show significant differences between 2 conditions, the effect size (η2 = .09) indicated that landing quality was better when participants adopted an external, rather than an internal focus of attention (P = .07). The body-oriented instructions can be provided externally by adding artificial external cues and directing attention to them. Importantly, the findings were evident in a qualitative assessment that can be adopted by practitioners. The results suggest that practitioners should adopt an external focus cue for performance and also consider using an external focus for movement quality.

5‐2: Invited Paper: Computational Eyeglasses and Near‐eye Displays with Focus Cues

In emerging VRIAR applications, the primary interface between the user and the digital world is the near‐eye display. However, today's VR/AR systems struggle to provide natural and comfortable viewing experiences, partly due to their fixed focal plane designs. In this paper, we discuss gaze‐contingent varifocal display designs for next‐generation computational near‐eye displays. Moreover, we discuss how the same technology components, eye tracking and focus‐tunable optics, can help presbyopes see the real world better. As humans age, they gradually lose the ability to accommodate, or refocus, to near distances because of the stiffening of the crystalline lens. This condition, known as presbyopia, affects nearly 20% of people worldwide. Here, we discuss the design and implementation of a new presbyopia correction, autofocals, to externally mimic the natural accommodation response, combining eye tracker and depth sensor data to automatically drive focus‐tunable lenses. With extensive user studies, we demonstrate that autofocals improve visual acuity over conventional monovision eyeglasses and task performance over progressives.

Volumetric Head-Mounted Display With Locally Adaptive Focal Blocks.

A commercial head-mounted display (HMD) for virtual reality (VR) presents three-dimensional imagery with a fixed focal distance. The VR HMD with a fixed focus can cause visual discomfort to an observer. In this article, we propose a novel design of a compact VR HMD supporting near-correct focus cues over a wide depth of field (from 18 cm to optical infinity). The proposed HMD consists of a low-resolution binary backlight, a liquid crystal display panel, and focus-tunable lenses. In the proposed system, the backlight locally illuminates the display panel that is floated by the focus-tunable lens at a specific distance. The illumination moment and the focus-tunable lens' focal power are synchronized to generate focal blocks at the desired distances. The distance of each focal block is determined by depth information of three-dimensional imagery to provide near-correct focus cues. We evaluate the focus cue fidelity of the proposed system considering the fill factor and resolution of the backlight. Finally, we verify the display performance with experimental results.

Geometrical-lightguide-based head-mounted lightfield displays using polymer-dispersed liquid-crystal films.

Integrating the promising waveguide or lightguide optical combiners to head-mounted lightfield display (LF-HMD) systems offers a great opportunity to achieve both a compact optical see-through capability required for augmented or mixed reality applications and true 3D scene with correct focus cues required for mitigating the well-known vergence-accommodation conflict. Due to the non-sequential ray propagation nature of these flat combiners and the ray construction nature of a lightfield display engine, however, adapting these two technologies to each other confronts several significant challenges. In this paper, we explore the feasibility of combining an integral-imaging-based lightfield display engine with a geometrical lightguide based on microstructure mirror arrays. The image artifacts and the key challenges in a lightguide-based LF-HMD system are systematically analyzed and are further quantified via a non-sequential ray tracing simulation. We further propose to utilize polymer-dispersed liquid-crystal (PDLC) films to address the inherent problems associated with a lightguide combiner such as increasing the viewing density and improving the image coupling uniformity. We finally demonstrate, to our best knowledge, the first lightguide-based LF-HMD system that takes the advantages of both the compact form factor of a lightguide combiner and the true 3D virtual image rendering capability of a lightfield display.