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Rate control is an important technique for practical video coding applications by allocating suitable quantization parameters (QPs) for CTUs or frames to satisfy bandwidth requirement. However, rate control may result in video quality fluctuation because neighboring regions are quantized into different quality levels, which may affect viewing experience seriously, especially at low bitrate scenarios. In this paper, we propose a novel CTU (Coding Tree Unit) level rate control approach for intra frame of the high efficiency video coding (HEVC) standard with consistent perceptual quality. In particular, a new perceptual hyperbolic rate distortion (R-D) optimization method is proposed for rate control with the constraint of constant perceptual quality, which shows good compatibility with other R-D models. Herein, a novel CTU level perceptual distortion model is presented to achieve the optimal rate control of intra frames for HEVC, where the Lagrange multiplier is adjusted by taking advantage of the different perceptual characteristics to achieve the minimal perceptual distortion variation across CTUs within one frame. Extensive experiments prove that the proposed algorithm outperforms the state-of-the-art CTU level rate control methods by considering R-D performance. In addition, subjective simulation results demonstrate that our algorithm further improves the visual quality of compressed videos by reducing perceptual quality fluctuation.

Age-related hearing loss (ARHL) is a devastating public health issue. To successfully address ARHL using existing and future treatments, it is imperative to detect the earliest signs of age-related auditory decline and understand the mechanisms driving it. Here, we explore early signs of age-related auditory decline by characterizing cochlear function in 199 ears aged 10–65 years, all of which had clinically defined normal hearing (i.e., behavioral thresholds ≤ 25 dB HL from .25 to 8 kHz bilaterally) and no history of noise exposure. We characterized cochlear function by measuring behavioral thresholds in two paradigms (traditional audiometric thresholds from .25 to 8 kHz and Békésy tracking thresholds from .125 to 20 kHz) and distortion product otoacoustic emission (DPOAE) growth functions at f(2) = 2, 4, and 8 kHz. Behavioral thresholds through a standard clinical frequency range (up to 8 kHz) showed statistically, but not clinically, significant declines across increasing decades of life. In contrast, DPOAE growth measured in the same frequency range showed clear declines as early 30 years of age, particularly across moderate stimulus levels (L(2) = 25–45 dB SPL). These substantial declines in DPOAE growth were not fully explained by differences in behavioral thresholds measured in the same frequency region. Additionally, high-frequency Békésy tracking thresholds above ~11.2 kHz showed frank declines with increasing age. Collectively, these results suggest that early age-related cochlear decline (1) begins as early as the third or fourth decade of life, (2) is greatest in the cochlear base but apparent through the length of the cochlear partition, (3) cannot be detected fully by traditional clinical measures, and (4) is likely due to a complex mix of etiologies.

What is it like to perceive a feared object? According to a popular neo-Gibsonian theory in psychology, fear biases our perceptions of objects so as to encourage particular kinds of actions: when we are afraid, spiders may be perceived as physically closer than they are in order to promote fleeing. Firestone mounted severe criticisms against this view, arguing that these cases are better explained by non-perceptual biases that operate on accurate perceptions of the external environment. In this paper I will argue that fear might indeed distort our perceptions of the world, but not in the way neo-Gibsonians suppose. In the view I favor, perceptual distortions occur as by-products of fearful attention, a special mode of attention that is part of an orchestrated defensive response that prepares the organism to deal effectively with a threat. To argue for this view I will rely on empirical evidence that fearful attention narrows down the focus of attention and favors processing of local rather than global features of stimuli, which may jointly explain why perceptual distortions might occur in fearful object seeing. This view has consequences not only for empirical investigations in fearful perceptual distortions, but also for an explanation of the intentionality of fear and the phenomenal integration of bodily and intentional elements in fear episodes.

Studies suggest looming motion represents a special class of attentional capture stimulus due to behavioral urgency: the need to act upon objects moving toward us in an environment. In particular, one theory suggests that faster reaction times to targets cued by looming relative to receding motion are driven by post-attentional, motor-priming processes beyond the attentional capture effects seen with other stimulus qualities such as color pop-out. The present study tested this theory using a relative size judgment task where targets were pre-cued by looming and receding optic flow fields. Results show systematic increases in the perceived size of targets that were cued by looming flow fields, consistent with previous attentional capture studies using onset cues. These results challenge theories attributing behavioral changes from looming motion to motor-priming alone.

The process of rate-distortion (RD) optimization plays a key role for video coding, which aims to achieve a tradeoff between compression efficiency and video quality distortion. Although the conventional objective distortion metric mean squared error performs well in computational complexity, it is not always in accordance with the perceptual quality perceived by human visual system (HVS). Taking the characteristics of HVS into consideration, a perceptually weighted mean squared error (PWMSE) based RD model is proposed in this work. First, a low-pass filter is employed to process the original distortion information in order to simulate visual signal processing and obtain the perceptual distortion. Then, masking modulation in both temporal and spatial domains is introduced into distortion model, and a novel Lagrange multiplier is derived accordingly. The proposed PWMSE based RD model is applied to the high efficiency video coding standard, and comparative experimental results demonstrate its effectiveness. The project page can be found in https://mic.tongji.edu.cn/ab/40/c9778a174912/page.htm .

In virtual reality (VR), how to map large-scale virtual spaces to small tracking area is a challenging problem. In this paper, we propose a novel steering algorithm for the redirected walking (RDW) technique to steer users away from the boundaries of the tracking area while reducing perceptible discrepancies. Inspired by the motion illusion that when a person is blindfolded, she goes in circles while thinking she is walking in a straight and infinitely long path, we map the path composed of straight-line segments in virtual space to a path composed of arcs in real space, and use one-step-ahead strategy and a buffer zone to reduce the number of user-boundary collisions. To verify the effectiveness of our algorithm, we conduct two experiments based on simulated in large-scale virtual spaces with a relatively small tracking area. The results indicate that our algorithm can effectively reduce collisions and perceptual distortion, and show the potential to address the challenge of simultaneously redirecting more than one user.

Many people who have undergone Anterior Cruciate Ligament (ACL)-reconstruction do not return to their pre-injury level, with nonphysical factors recognized as barriers to recovery. Fear of movement has been linked to body schema distortions, and interventions directed at the body schema have shown potential to improve function. 1) Describe participants’ ability to perform a visual imagery intervention (Body Scan); 2) investigate knee perception differences; 3) investigate if Body Scan led to improvements in perceptual differences; and 4) determine if some individuals improved in functional measures following the intervention. A single-arm intervention study was undertaken in people >12-month post ACL-reconstruction (n = 30). Body Scan was delivered using a standardized script developed for this study. Participants were assessed regarding their capacity to perform the Body Scan, perceptual differences between the knees and how perception changed following the intervention. Functional measures (vertical hop, triple hop, mSEBT, quadriceps strength, and hamstring strength) were taken. 96.7% were able to perform a Body Scan, with 93.1% demonstrating a difference in perception between the knees. Of participants with perceptual differences, 92.5% demonstrated improvement in perception following the intervention. Ten participants had a clinically significant improvement in a functional measure following the intervention. Most participants could perform Body Scanning. The majority perceived perceptual differences between operated and non-operated knees, and reported more symmetric perception following the intervention. One-third of participants also showed improvements in a functional performance measure. Results suggest this intervention may be a helpful adjunct to rehabilitation post ACL-reconstruction, with further research warranted.

We live in a dynamic, distracting world. When distracting information captures attention, what are the consequences for perception? Previous literature has focused on effects such as reaction time (RT) slowing, accuracy decrements, and oculomotor capture by distractors. In the current study, we asked whether attentional capture by distractors can also more fundamentally alter target feature representations, and if so, whether participants are aware of such errors. Using a continuous report task and novel confidence range report paradigm, we discovered 2 types of feature-binding errors when a distractor was presented along with the target: First, when attention is strongly captured by the distractor, participants commit swapping errors (misreporting the color at the distractor location instead of the target color), which remarkably seem to occur without awareness. Second, when participants successfully resist capture, they tend to exhibit repulsion (perceptual distortion away from the color at the distractor location). Thus, we found that capture not only induces a spatial shift of attention, it also alters feature perception in striking ways. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Aim: Body awareness arises when attending to and maintaining awareness of visuospatial body representations. By the same token, focussing on representations transfers them to working memory. Body awareness and working memory seemingly rely on similar processes and recruit common parietal areas involved in perception. Therefore, we asked whether visuospatial working memory abilities would define individual differences in the perception of spontaneous sensations (SPS), i.e., bodily sensations perceived in the absence of triggers (e.g., tactile stimulation or movement), when attending to the body.Method: Participants completed two visuospatial working memory tasks to assess various mechanisms: (i) the decay of representations was assessed through a Brown-Peterson task in which the delay between the memorandum presentation and its recall was manipulated, and (ii) the impact of distractors' interference and cognitive load (i.e., complexity) on recall performances were assessed through a complex span task that required the processing of distractors while maintaining a memorandum. A standard SPS task involving localization and characterization of SPS perceived on the hands was completed afterwards.Results: Low performance due to decay, distractors' interference and cognitive load in visuospatial working memory was associated with a decrease in the frequency of SPS. Additionally, low performance due to distractors' cognitive load predicted a decrease in the perception of surface-type sensations, and high performance despite distractors' interference led to a better perception of SPS on less sensitive areas of the hand.Conclusion: We discuss how visuospatial working memory processes might contribute to body awareness and perceptual distortions of the body.

We propose a multi-task learning neural network for No-Reference image quality assessment (NR-IQA). The pro-posed architecture consists of a backbone feature extractor, a nested multi-task generative module and a quality regression module. We adopt a coarse-to-fine strategy to predict objective error maps in two subtasks optimized with different loss functions. The network is designed to be nested such that discriminative features learned from subtasks are efficiently shared by the primary task. Perceptual distortion maps are achieved by applying masking mechanism between reconstructed error maps and the learned distortion sensitivity map. At last, a quality regression module is adopted to nonlinearly map masked distortions to the subjective score. Experimental results demonstrate the superior performances of the proposed model over state-of-the-art models. The implementation of our method is released at https://github.com/R-JunmingChen/NEMG-IQA.

Background Voluntary movement such as lifting a foot in preparation to stepping acts as a self-initiated perturbation that disturbs postural equilibrium. To maintain and restore equilibrium, humans utilize early, anticipatory, and compensatory postural adjustments. Despite technological progress in accessible virtual reality (VR) devices, little is known on the usage of VR in control and maintenance of balance while standing. Research question How does VR modulate early, anticipatory, and compensatory postural adjustments during a dynamic task of leg lifting while avoiding an obstacle? Methods First, the postural adjustments in a single-leg obstacle avoidance were compared between real and VR settings, where a statistical reanalysis was performed with data subsets that minimize the difference of foot elevation speed. Second, the effect of simple foot elevation was examined to identify the fundamental nature of leg lifting motion as a self-initiated perturbation. Lastly, perceptual distortion in VR was assessed by evaluating how the spatial scale of the virtual scene used in the single-leg obstacle avoidance experiment was recognized by participants. Results The VR setting reduced the activities of lower leg muscles on the supporting side not only in the compensatory phase but also in the preparatory early and anticipatory phases. On the other hand, simple foot elevation resulted in a significant increase of muscle activities with lifting height only found in the compensatory phase. Furthermore, it is suggested that the VR induced perceptual distortion in estimating the sizes of the virtual objects. Significance The findings provide more definitive evidence that VR presentation modulates the components of postural adjustments for maintaining upright stance while being perturbed. One of the potential psychophysical factors is perceptual distortion in VR, and this provides critical information for further development of VR based training system.

No-reference (NR) perceptual video quality assessment (VQA) is a complex, unsolved, and important problem for social and streaming media applications. Efficient and accurate video quality predictors are needed to monitor and guide the processing of billions of shared, often imperfect, user-generated content (UGC). Unfortunately, current NR models are limited in their prediction capabilities on real-world, "in-the-wild" UGC video data. To advance progress on this problem, we created the largest (by far) subjective video quality dataset, containing 38,811 real-world distorted videos and 116,433 space-time localized video patches (‘v-patches’), and 5.5M human perceptual quality annotations. Using this, we created two unique NR-VQA models: (a) a local-to-global region-based NR VQA architecture (called PVQ) that learns to predict global video quality and achieves state-of-the-art performance on 3 UGC datasets, and (b) a first-of-a-kind space-time video quality mapping engine (called PVQ Mapper) that helps localize and visualize perceptual distortions in space and time. The entire dataset and prediction models are freely available at https://live.ece.utexas.edu/research.php.

Most current audio steganographic methods are content non-adaptive which have poor security and low embedding capacity. This paper proposes a generalized adaptive Huffman code mapping (AHCM) framework for obtaining higher secure payload. To avoid the frame-offset effect of audio codec, we first establish a distortion-limited suppressible code space, which realizes data embedding by using equal-length entropy codes. Furthermore, a stego key is used to dynamically build Huffman code mapping of each frame for improving acoustic imperceptibility and statistical undetectability. We then consider integrating psychoacoustic model (PAM) of intra-frame with frame-level perceptual distortion of inter-frame to obtain minimized total distortion. Finally, we present an implementation of the proposed AHCM framework on MP3 audios. A distortion function based on the PAM and an optimal steganographic frame path are, respectively, devised for adaptively embedding via employing syndrome-trellis codes. Experimental results demonstrate that our approach is, indeed, able to achieve higher secure steganographic capacity and better acoustic concealment. The detection accuracy of 320-kbps-mp3 datasets is lower than 65% when the embedding payload reaches 11 kbps, which is decreased by 11.8%–13.4% than the state-of-the-art steganographic methods.

BACKGROUND A recent study has shown variability on the perception of verticality during unilateral centrifugation among patients with type 2 diabetes mellitus; it is yet unknown if it is related to symptoms of unreality. OBJECTIVE In patients with type 2 diabetes mellitus compared to age matched healthy volunteers, to assess depersonalization/derealization (DD) symptoms before and after unilateral centrifugation, according to the subjective visual vertical (SVV). METHODS 47 patients with type 2 diabetes mellitus and 50 age matched healthy volunteers participated in the study. They replied to standardized questionnaires of symptoms related to balance, depression, and anxiety. Then, after neuro-otological evaluation, they completed a DD inventory before and after unilateral centrifugation (300°/s, 3.85 cm) with SVV estimation. RESULTS Right/left asymmetric SVV during centrifugation was identified in 17 patients (36%) and no SVV change during centrifugation was identified in 6 patients (13%). Before centrifugation, patients with asymmetric SVV already reported some of the DD symptoms, while patients with no SVV change reported almost no DD symptoms. Unilateral centrifugation provoked an increase of DD symptoms in both healthy volunteers and the entire group of patients (repeated measures ANOVA, p

Amblyopia is a relatively common (incidence 3%) developmental disorder in which there is loss of vision as a consequence of a disruption to normal visual development. Although the deficit is monocular and known to be of cortical origin, the nature of the processing deficit is controversial. Human behavioral studies have identified two main deficits - a loss of contrast sensitivity and perceived spatial distortions. Here we use a multifocal fMRI approach to ascertain, in a group of anisometropic amblyopes, whether these two deficits have a single common cause or whether they are the result of two underlying independent cortical disorders. We found that fMRI magnitudes were attenuated in amblyopic eye stimulation, and that there was poor fidelity for co-localization of the activity clusters between the amblyopic and fellow-fixing eye stimulation. These effects varied across eccentricities and correlate with the degree of amblyopia but not with one another, suggesting two independent cortical deficits: a reduced responsiveness as well as reduced fidelity of spatial representation. These deficits are independent of eccentricity within the central field and consistent across early cortical visual areas.

The digital medical workflow faces many circumstances in which the images can be manipulated during viewing, extracting and exchanging. Reversible and imperceptible watermarking approaches have the potential to enhance trust within the medical imaging pipeline through ensuring the authenticity and integrity of the images to confirm that the changes can be detected and tracked. This study concentrates on the imperceptibility issue. Unlike reversibility, for which an objective assessment can be easily made, imperceptibility is a factor of human cognition that needs to be evaluated within the human context. By defining a perceptual boundary of detecting the modification, this study enables the formation of objective guidelines for the method of data encoding and level of image/pixel modification that translates to a specific watermark magnitude. \ud This study implements a relative Visual Grading Analysis (VGA) evaluation of 117 brain MR images (8 original and 109 watermarked), modified by varying techniques and magnitude of image/pixel modification to determine where this perceptual boundary exists and relate the point at which change becomes noticeable to the objective measures of the image fidelity evaluation. \ud The outcomes of the visual assessment were linked to the images Peak Signal to Noise Ratio (PSNR) values, thereby identifying the visual degradation threshold. The results suggest that, for watermarking applications, if a watermark is applied to the 512x512 pixel (16 bpp grayscale) images used in the study, a subsequent assessment of PSNR=82dB or greater would mean that there would be no reason to suspect that the watermark would be visually detectable. \ud Keywords: Medical imaging; DICOM; Reversible Watermarking; Imperceptibility; Image Quality; Visual Grading Analysis.

Multi-view video coding (MVC) utilizes hierarchical B picture prediction structure and adopts many coding techniques to remove spatiotemporal and inter-view redundancies at the cost of high computational complexity. In this paper, a novel perceptual distortion threshold model (PDTM) is proposed to reveal the relationship between the mode selection of inter-frame prediction and coding distortion threshold. Based on the proposed PDTM, a new fast inter-frame prediction algorithm in MVC is developed aimed at minimizing computational complexity for dependent view coding. Then the fast MVC algorithm is incorporated into the multi-view High Efficiency Video Coding (MV-HEVC) software to improve MVC coding efficiency. In practical coding, the mode selection for inter-frame prediction of dependent views may be early terminated based on the thresholds derived from the PDTM, thereby reducing the coding time complexity. Experimental results demonstrate that the proposed algorithm can reduce the computational complexity of the dependent views by 52.9% compared with the HTM14.1 algorithm under the coding structure of hierarchical B pictures. Moreover, the bitrate is increased by 0.9% under the same subjective quality and only increased by 1.0% under the same objective quality peak signal-to-noise ratio (PSNR). Compared with the state-of-the-art fast algorithm, the proposed algorithm can save more coding time, while the bitrate under the same PSNR increases slightly.

High efficiency video coding (HEVC) is standard in the video compression field and performs well not only in video compression coding, but also in image compression. Regions of interest (ROIs) and just noticeable difference (JND), two human visual models, can accurately quantify human visual system (HVS) characteristics as pixel values. Using ROIs and JND to assist in evaluating image distortion can effectively reduce human visual redundancy and reflect authentic perceptual distortions. However, they are not readily applicable to the HEVC test model (HM) in the pixel domain. It is difficult to secure a suitable Lagrange multiplier $\lambda $ and quantization parameter (QP) for the JND model in particular. This paper proposes different solutions for the use of rate control (RC) or not where an appropriate $\lambda $ value is available for perceptual models. In RC, the proposed approach centers on a robust relationship between QP and achieved $\lambda $ . And we also established a bit allocation technique using the related $\lambda $ and expression for the RC model. Experimental results validate the rationality and effectiveness of the proposed method.

Reversible and imperceptible watermarking is recognized as a robust approach to confirm the integrity and authenticity of medical images and to verify that alterations can be detected and tracked back. In this paper, a novel blind reversible watermarking approach is presented to detect intentional and unintentional changes within brain Magnetic Resonance (MR) images. The scheme segments images into two parts; the Region of Interest (ROI) and the Region of Non Interest (RONI). Watermark data is encoded into the ROI using reversible watermarking based on the Difference Expansion (DE) technique. Experimental results show that the proposed method, whilst fully reversible, can also realize a watermarked image with low degradation for reasonable and controllable embedding capacity. This is fulfilled by concealing the data into ‘smooth’ regions inside the ROI and through the elimination of the large location map required for extracting the watermark and retrieving the original image. Our scheme delivers highly imperceptible watermarked images, at 92.18–99.94 dB Peak Signal to Noise Ratio (PSNR) evaluated through implementing a clinical trial based on relative Visual Grading Analysis (relative VGA). This trial defines the level of modification that can be applied to medical images without perceptual distortion. This compares favorably to outcomes reported under current state-of-art techniques. Integrity and authenticity of medical images are also ensured through detecting subsequent changes enacted on the watermarked images. This enhanced security measure, therefore, enables the detection of image manipulations, by an imperceptible approach, that may establish increased trust in the digital medical workflow.

The susceptibility of distortions introduced by compression from the point of view of human perception is an important area of research. The ultimate purpose of video quality assessment is to emulate the performance of the biological visual system. Perceptual distortion models have proven successful in describing spatial coding in all human visual systems. However, the question of how the visual regions of the human brain process temporal information have received significantly less attention. Based on the researches of limit to human vision, here we offer a method, software, and test equipment for research and measure the characteristics of human visual systems. This set forms and evaluates stimuli with a specified combination of spatial, temporal, and color characteristics, which differ in a narrowband enough spectrum for measurements.

In this paper, we concentrate on the super-resolution (SR) of compressed screen content video, in an effort to address the real-world challenges by considering the underlying characteristics of screen content. Firstly, we propose a new dataset for the SR of screen content video with different distortion levels. Meanwhile, we design an efficient SR structure that could capture the characteristics of compressed screen content video and manipulate the inner-connections in consecutive compressed low-resolution frames, facilitating the high-quality recovery of the high-resolution counter-part. Moreover, we design a new loss function for network training to better remedy the compression distortion and perceptual distortion. Experimental results demonstrate the effectiveness and superiority of the proposed method.

For omnidirectional videos (ODVs), the existing off-line coding approaches are designed based on the spatial or perceptual distortion in a whole ODV frame, ignoring the fact that subjects can only access viewports. To improve the subjective quality inside the viewports, this paper proposes an off-line viewport-adaptive rate control (RC) approach for ODVs in high efficiency video coding (HEVC) framework. Specifically, we predict the viewport candidates with importance weights and develop a viewport saliency detection model. Then, the predicted candidates and detected saliency are taken into account in our viewport-adaptive CTU traversal and bit allocation scheme. Finally, the experimental results validate that our approach is effective in saving bit-rates and improving subjective quality for encoding ODVs; meanwhile, our approach is also effective in the auxiliary task of saliency detection in viewports.

BackgroundIn individuals with body dysmorphic disorder (BDD), selective attention biases and aberrant visual scanning patterns may cause imbalances in global vs. detailed visual processing, contributing to perceptual distortions for appearance. The mechanistic effects of modifying visual attention on brain function in BDD, which may be critical to developing perceptual-based treatments, have not been explored. This study tested the effects of visual-attention modulation on dorsal and ventral visual stream activation and connectivity, and eye behaviors.MethodsWe acquired functional magnetic resonance imaging data in 37 unmedicated adults with BDD and 30 controls. Participants viewed their faces under two conditions: a) unconstrained (naturalistically), and b) holding their gaze on the center of the image (visual-attention modulation), monitored with an eye-tracking camera. We analyzed activation and dynamic effective connectivity in dorsal and ventral visual streams and visual fixation duration.ResultsVisual-attention modulation resulted in longer fixation duration and reduced activation in dorsal and ventral visual streams in both groups compared with naturalistic viewing. Longer fixation duration was associated with greater effective connectivity from V1 to early dorsal visual stream during the second naturalistic viewing, across groups. During naturalistic viewing, there was greater V1 to early dorsal visual stream connectivity after, compared with before, visual-attention modulation.ConclusionsWhen viewing one’s face, longer visual fixation may confer greater communication in dorsal visual system, facilitating global/holistic visual processing. The finding that reduction in visual scanning while viewing one’s face results in persistent effects during unconstrained viewing has implications for perceptual retraining treatment design for BDD.

Concurrent body movements have been shown to enhance the accuracy of spatial judgment, but it remains unclear whether they also contribute to perceptual estimates of gravitational space not involving body movements. To address this, we evaluated the effects of static or dynamic arm movements during prolonged whole-body tilt on the subsequent perceptual estimates of visual or postural vertical. In Experiment 1, participants were asked to continuously perform static or dynamic arm movements during prolonged tilt, and we assessed their effects on the prolonged tilt-induced shifts of subjective visual vertical (SVV) at a tilted position (during-tiltsession) or near upright (post-tiltsession). In Experiment 2, we evaluated how static or dynamic arm movements during prolonged tilt subsequently affected the subjective postural vertical (SPV). In Experiment 1, we observed that the SVV was significantly shifted toward the direction of prolonged tilt in both sessions. The SVV shifts decreased when performing dynamic arm movements in theduring-tiltsession, but not in thepost-tiltsession. In Experiment 2, as well as SVV, the SPV was shifted toward the direction of prolonged tilt, but it was not significantly attenuated by the performance of static or dynamic arm movements. The results of theduring-tiltsession suggest that the central nervous system utilizes additional information generated by dynamic body movements for perceptual estimates of visual vertical.

The sources and consequences of a sensorineural hearing loss are diverse. While several approaches have aimed at disentangling the physiological and perceptual consequences of different etiologies, hearing deficit characterization and rehabilitation have been dominated by the results from pure-tone audiometry. Here, we present a novel approach based on data-driven profiling of perceptual auditory deficits that attempts to represent auditory phenomena that are usually hidden by, or entangled with, audibility loss. We hypothesize that the hearing deficits of a given listener, both at hearing threshold and at supra-threshold sound levels, result from two independent types of “auditory distortions”. In this two-dimensional space, four distinct “auditory profiles” can be identified. To test this hypothesis we gathered a dataset consisting of a heterogeneous group of listeners that were evaluated using measures of speech intelligibility, loudness perception, binaural processing abilities and spectro-temporal resolution. The subsequent analysis revealed that distortion type-I was associated with elevated hearing thresholds at high frequencies and reduced temporal masking release and was significantly correlated with elevated speech reception thresholds in noise. Distortion type-II was associated with low-frequency hearing loss and abnormally steep loudness functions. The auditory profiles represent four robust subpopulations of hearing-impaired listeners that exhibit different degrees of perceptual distortions. The four auditory profiles may provide a valuable basis for improved hearing rehabilitation, e.g. through profile-based hearing-aid fitting

Continuous human annotations of complex human experiences are essential for enabling psychological and machine-learned inquiry into the human mind, but establishing a reliable set of annotations for analysis and ground truth generation is difficult. Measures of consensus or agreement are often used to establish the reliability of a collection of annotations and thereby purport their suitability for further research and analysis. This work examines many of the commonly used agreement metrics for continuous-scale and continuous-time human annotations and demonstrates their shortcomings, especially in measuring agreement in general annotation shape and structure. Annotation quality is carefully examined in a controlled study where the true target signal is known and evidence is presented suggesting that annotators' perceptual distortions can be modeled using monotonic functions. A novel measure of agreement is proposed which is agnostic to these perceptual differences between annotators and provides unique information when assessing agreement. We illustrate how this measure complements existing agreement metrics and can serve as a tool for curating a reliable collection of human annotations based on differential consensus.

A longstanding debate in the face recognition field concerns the format of face representations in the brain. New face research clarifies some of this mystery by revealing a face-centered format in a patient with a left splenium lesion of the corpus callosum who perceives the right side of faces as ‘melted’.

Anorexia nervosa (AN) and body dysmorphic disorder (BDD) are characterized by distorted perception of appearance, yet no studies have directly compared the neurobiology associated with body perception. We compared AN and BDD in brain activation and connectivity in relevant networks when viewing images of others' bodies and tested their relationships with clinical symptoms and subjective appearance evaluations. We acquired fMRI data from 64 unmedicated females (20 weight-restored AN, 23 BDD, 21 controls) during a matching task using unaltered or spatial-frequency filtered photos of others' bodies. Using general linear model and independent components analyses we compared brain activation and connectivity in visual, striatal, and parietal networks and performed univariate and partial least squares multivariate analyses to investigate relationships with clinical symptoms and appearance evaluations. AN and BDD showed partially overlapping patterns of hyperconnectivity in the dorsal visual network and hypoconnectivity in parietal network compared with controls. BDD, but not AN, demonstrated hypoactivity in dorsal visual and parietal networks compared to controls. Further, there were significant activity and connectivity differences between AN and BDD in both networks. In both groups, activity and/or connectivity were associated with symptom severity and appearance ratings of others' bodies. Thus, AN and BDD demonstrate both distinct and partially-overlapping aberrant neural phenotypes involved in body processing and visually encoding global features. Nevertheless, in each disorder, aberrant activity and connectivity show relationships to clinically relevant symptoms and subjective perception. These results have implications for understanding distinct and shared pathophysiology underlying perceptual distortions of appearance and may inform future novel treatment strategies.

Steganography is a technique of concealing the message in multimedia data. Multimedia data, such as videos are often compressed to reduce the storage for limited bandwidth. The video provides additional hidden-space in the object motion of image sequences. This research proposes a video steganography scheme based on object motion and DCT-psychovisual for concealing the message. The proposed hiding technique embeds a secret message along the object motion of the video frames. Motion analysis is used to determine the embedding regions. The proposed scheme selects six DCT coefficients in the middle frequency using DCT-psychovisual effects of hiding messages. A message is embedded by modifying middle DCT coefficients using the proposed algorithm. The middle frequencies have a large hiding capacity and it relatively does not give significant effect to the video reconstruction. The performance of the proposed video steganography is evaluated in terms of video quality and robustness against MPEG compression. The experimental results produce minimum distortion of the video quality. Our scheme produces a robust of hiding messages against MPEG-4 compression with average NC value of 0.94. The proposed video steganography achieves less perceptual distortion to human eyes and it's resistant against reducing video storage.

Additional gravitational cues generated by active body movements may play a role in the perception of gravitational space, but no experimental evidence has been shown on this. To investigate this possibility, we evaluated how arm movements made against gravity influenced the perceptual distortion of visual and postural vertical induced by prolonged whole-body tilt. In Experiment 1, participants were asked to perform static or dynamic arm movements during prolonged whole-body tilt and we assessed their effects on subjective visual vertical (SVV) at the tilt position (during-tiltsession) and after tilting back to the upright position (post-tiltsession). In Experiment 2, we evaluated how static or dynamic arm movements during prolonged tilt subsequently affected the subjective postural vertical (SPV). In Experiment 1, we observed that prolonged tilt induced the SVV shifts toward the side of body tilts in both sessions. The prolonged tilt-induced SVV shifts effectively decreased when performing dynamic arm movements in theduring-tiltsession, but not in thepost-tiltsession. In Experiment 2, the SPV shifted toward the side of prolonged body tilt, which was not significantly influenced by the performance of static or dynamic arm movements. Results of theduring-tiltsession suggest that the central nervous system utilizes additional cues generated by dynamic body movements for the perception of the visual vertical.

Stereopsis and motion parallax provide depth information, capable of producing more realistic user experiences after being integrated into a flat screen (e.g. immersive virtual reality). Extensive research shows that stereoscopic screens increase realism, while few studies have investigated users’ responses to parallax screens without stereopsis. In this study, we examined users’ evaluations of screens with only parallax or stereopsis. We found that with only parallax, the mapping between observer motion and viewpoint change should be around 0.6 for a more realistic perceptual experience, and observers were less sensitive to stereoscopic distortions as a result of a different interpupillary distance scaling.

Given that mechanoreceptors are highly heterogeneously distributed and there is no direct sensory signal of the distribution, it must be challenging for the brain to identify stimuli in external space by remapping sensory inputs. Some previous studies reported perceptual distortion of tactile space, reflecting a difference in scales for different body parts. Here we report another example in which the orientation of stimuli perceived on the arm is rotated regionally, or even flipped. This illusion cannot be explained simply in terms of the resolution difference of mechanoreceptors.

Objectives: The aims were to use different techniques to assess the degree of sensory changes and magnitude of perceived size changes in the facial region induced by nerve blocks of two different trigeminal nerve branches in healthy participants. Materials and methods: This placebo-controlled study included 30 healthy volunteers. The participants underwent quantitative and qualitative sensory testing (QST and QualST) thrice: before, 10 min, and 2 h after mental (n = 15) and infraorbital (n = 15) nerve blocks and during control (saline) sessions. Perceived numbness, temperature changes, and perceptual distortion were also measured at all time points during the nerve block and control sessions. Differences in outcome parameters between the sessions and time points were analyzed using analyses of variance and McNemar’s tests. Results: There was a significant degree of sensory loss to most QST and all QualST parameters, with significant numbness and increased perceived size at the injection site 10 min and 2 h after the nerve blocks compared with saline (P < 0.030) and the baseline (P < 0.042). Two hours after the nerve blocks, the sensitivity was significantly closer to baseline than after 10 min to most of the QST parameters (P < 0.011). Conclusions: QST and QualST revealed that the nerve blocks in the orofacial region resulted in complete or partial blockade of afferent nerve fibers mediating thermal and mechanical function for more than 2 h with significant numbness and perceptual distortion. Clinical relevance: Both QST and QualST can provide information on the degree of blockade of afferent nerve fibers after nerve blocks in the orofacial region.

An object appears smaller in the periphery than in the center of the visual field. In two experiments ( N = 24), we demonstrated that visuospatial attention contributes substantially to this perceptual distortion. Participants judged the size of central and peripheral target objects after a transient, exogenous cue directed their attention to either the central or the peripheral location. Peripheral target objects were judged to be smaller following a central cue, whereas this effect disappeared completely when the peripheral target was cued. This outcome suggests that objects appear smaller in the visual periphery not only because of the structural properties of the visual system but also because of a lack of spatial attention.

We used a novel method to capture the spatial dominance pattern of competing motion fields at rivalry onset. When rivaling velocities were different, the participants reported center-surround segmentation: The slower stimuli often dominated in the center while faster motion persisted along the borders. The size of the central static/slow field scaled with the stimulus size. The central dominance was time-locked to the static stimulus onset but was disrupted if the dynamic stimulus was presented later. We then used the same stimuli as masks in an interocular suppression paradigm. The local suppression strengths were probed with targets at different eccentricities. Consistent with the center-surround segmentation, target speed and location interacted with mask velocities. Specifically, suppression power of the slower masks was nonhomogenous with eccentricity, providing a potential explanation for center-surround velocity-based segmentation. This interaction of speed, eccentricity, and timing has implications for motion processing and interocular suppression. The influence of different masks on which target features get suppressed predicts that some "unconscious effects" are not generalizable across masks and, thus, need to be replicated under various masking conditions.

Due to various reasons an image may get distorted. To measure the perceptual distortions, image quality assessment (IQA) metrics are required. Peak-signal-to-noise-ratio (PSNR) is one of the popular available IQA metric. It is usually measured by computing distortion in terms of mean-squared-error (MSE) between the reference image and its distorted version. Mean-squared-error (MSE) is measured over the entire image by giving equal weight to each corresponding pixel difference of the reference and distorted image. However, as per investigation done in this paper, it is found that instead of calculating MSE/PSNR on overall image, PSNR measured over the region of maximum distortion only is a better choice. The PSNR computed over the most distorted region (PSNR-MDR) reflects the image quality better than it computed over entire image. The PSNR-MDR is not only superior to the PSNR but also competitive to celebrated metric, SSIM (Structural Similarity Index).

In computer graphics, various processing operations are applied to 3D triangle meshes and these processes often involve distortions, which affect the visual quality of surface geometry. In this context, perceptual quality assessment of 3D triangle meshes has become a crucial issue. In this paper, we propose a new objective quality metric for assessing the visual difference between a reference mesh and a corresponding distorted mesh. Our analysis indicates that the overall quality of a distorted mesh is sensitive to the distortion distribution. The proposed metric is based on a spatial pooling strategy and statistical descriptors of the distortion distribution. We generate a perceptual distortion map for vertices in the reference mesh while taking into account the visual masking effect of the human visual system. The proposed metric extracts statistical descriptors from the distortion map as the feature vector to represent the overall mesh quality. With the feature vector as input, we adopt a support vector regression model to predict the mesh quality score.We validate the performance of our method with three publicly available databases, and the comparison with state-of-the-art metrics demonstrates the superiority of our method. Experimental results show that our proposed method achieves a high correlation between objective assessment and subjective scores.

This paper presents a blind and robust audio watermarking algorithm developed based on Fibonacci numbers properties and the discrete wavelet transform (DWT) advantages. The method embeds watermark bits in the 6th level approximation subband of DWT at which there is less sensitivity of the human auditory system. The key idea is dividing the 6th level approximation coefficients into small frames and modifying their magnitude based on Fibonacci numbers and watermark bit values. The proposed watermarking method demonstrates a superior robustness against different common attacks (i.e., Gaussian noise addition, Low-pass filter, Resampling, Requantizing, MP3 compression, Amplitude scaling, Echo addition, Time shift, and Cropping). Compared to recently developed methods, the proposed algorithm is much more robust against the most common attacks with capacity as high as 686 bits per second. The results of PEAQ testing verify the quality of watermarked audio signal without significant perceptual distortion. The algorithm allows flexibility in audio watermark algorithm to achieve a balance between robustness and imperceptibility while the capacity is maintained constant by choosing various kinds of sequence.

High efficiency video coding (HEVC) is the latest video coding standard, and it has the best performance among all the existing standards. HEVC main still picture profile (HEVC-MSP) also achieves top performance in image compr-ession. In this paper, we propose a closed-form bit allocation approach to optimize the saliency-guided PSNR (viewed as perceptual distortion) such that the coding efficiency of HEVC-based image compression can be significantly improved from a subjective perspective. Specifically, a bit allocation formulation is established to minimize perceptual distortion with a constraint on bit-rates. Then, this formulation is solved using the proposed recursive Taylor expansion method with a closed-form solution. On the basis of our solution, a bit allocation and re-allocation process is developed in our approach to minimize perceptual distortion, meanwhile accurately controlling bit-rates. In addition, we provide both theoretical and numerical analyses of the computational complexity, verifying the little extra time cost of our approach. The experimental results demonstrate the superior performance of our approach over the state-of-the-art HEVC-MSP, and the BD-rate savings are approximately 40% and 24% for face and generic images, respectively.

Purpose: The Enright phenomenon describes the distortion in speed perception experienced by an observer looking sideways from a moving vehicle when viewing with interocular differences in retinal image brightness, usually induced by neutral density filters. We investigated whether the Enright phenomenon could be induced with monocular pupil dilation using tropicamide. Methods: We tested 17 visually normal young adults on a closed road driving circuit. Participants were asked to travel at Goal Speeds of 40 km/h and 60 km/h while looking sideways from the vehicle with: (i) both eyes with undilated pupils; (ii) both eyes with dilated pupils; (iii) with the leading eye only dilated; and (iv) the trailing eye only dilated. For each condition we recorded actual driving speed. Results: With the pupil of the leading eye dilated participants drove significantly faster (by an average of 3.8 km/h) than with both eyes dilated (p = 0.02); with the trailing eye dilated participants drove significantly slower (by an average of 3.2 km/h) than with both eyes dilated (p

With the development of high-dynamic-range images and tone mapping operators comes a need for image quality evaluation of tone mapped images. However, because of the significant difference in dynamic range between high-dynamic-range images and tone mapped images, conventional image quality assessment algorithms that predict distortion based on the magnitude of intensity or normalized contrast are not suitable for this task. In this article, we present a feature-based quality metric for tone mapped images that predicts the perceived quality by measuring the distortion in important image features that affect quality judgment. Our metric utilizes multi-exposed virtual photographs taken from the original high-dynamic-range images to bridge the gap between dynamic ranges in image feature analysis. By combining measures for brightness distortion, visual saliency distortion, and detail distortion in light and dark areas, the metric measures the overall perceptual distortion and assigns a score to a tone mapped image. Experiments on a subject-rated database indicate that the proposed metric is more consistent with subjective evaluation results than alternative approaches.

Methods for spectral complexity reduction of music signals were evaluated in a listening test with cochlear implant (CI) listeners. To this end, reduced-rank approximations were computed in the constant-Q spectral domain using blind and score-informed dimensionality reduction techniques, which were compared to a procedure using a supervised source separation and remixing scheme. Previous works have shown that timbre and pitch cues are transmitted inaccurately through CIs and thus cause perceptual distortions in CI listeners. Hence, the scope of this evaluation was narrowed down to classical chamber music, which is mainly characterized by timbre and pitch and less by rhythmic cues. Suitable music pieces were selected in accordance to a statistical experimental design, which took musically relevant influential factors into account. In a blind two-alternative forced choice task, 14 CI listeners were asked to indicate a preference either for the original signals or a specific processed variant. The results exhibit a statistically significant preference rate of up to 74% for the reduced-rank approximations, whereas the source separation and remixing scheme did not provide any improvement.

Dynamic distortion of the visual field has been shown to affect perceptual judgment of visual dimensions such as size, length, and distance. Here, we report four experiments demonstrating that the different aspects of a triangle differently influence judgments of distance. Specifically, when the base of the triangle faces the centre of the display, participants consistently underestimate and overestimate the distance of a small dot from the unmarked centre of the display relative to conditions in which the vertex of the triangle faces the centre. When the dot is close to the figure, the distance of the dot to the centre is underestimated. Conversely, when the dot is close to the figure, the distance to the centre is overestimated. The effect is replicated when the internal distances are equalized and when ellipses are used instead of triangles. These results support a ripple model of spatial distortion in which local curvature acts to attract or repel objects. In conclusion, we suggest some implications of our findings for theories of perceptual organization.

Parkinson's disease (PD) is a movement disorder caused by deterioration of the dopaminergic system. Previous studies have demonstrated temporal as well as emotional facial recognition impairment in PD patients. Moreover, it has been demonstrated that emotional facial expressions alter temporal judgments. In the present study, we investigate the magnitude of temporal distortions caused by the presentation of emotional facial expressions (happiness, sadness, and neutral) in PD patients with mild cognitive impairment (PD-MCI) and controls.Seventeen older adults with PD-MCI and 22 healthy older adults took part in the present study. Participants were tested with a time bisection task with standard intervals lasting 400 ms and 1600 ms. Moreover, a complete neuropsychological evaluation was conducted to characterize the sample.Differences between groups were observed indicating a general underestimation of time in PD-MCI patients. Temporal impairments in PD-MCI patients seem to be caused mainly by a dysfunction at the level of reference memory. The effect of emotional facial expressions on time perception was evident in both PD patients and controls, with an overestimation of perceived duration when happiness was presented and an underestimation when sadness was presented.Overall, our results indicate that reduced cognitive abilities might be responsible for the lower temporal ability observed in PD-MCI patients. Moreover, similar effects of emotional stimuli were observed in both PD-MCI patients and controls.

The feeling of hunger is an inseparable part of people's daily lives. It has been established that hunger, caused by food deprivation, influences people's physiological and emotional state and their everyday behavior. Yet, it remains unclear whether and in which manner food deprivation affects the way people perceive their environment. In two experiments, we examined the effects of food deprivation on the perceptual resolution of food portion size. We calculated Just Noticeable Differences (JNDs) to measure sensitivity to detect the smallest difference between two stimuli of different sizes. Participants' resolution in both experiments was higher to detect changes in food size compared with baseline when they were hungry due to a short period of food deprivation. Food deprivation did not lead to any biases in the average perception of food size. The results show that food deprivation changes the way people perceive their environment. We discuss the possible role of attention in mediating the effect of food deprivation on the visual resolution of food size.

Abstract: The aim of this literature review is to integrate the results of various studies regarding body image and body image distortion into a unified framework. The concept of body image is complex and can be interpreted from multiple points of view. The first part of the study touches upon different age characteristics, attentional focus on the body, the early and important role of the body in identity formation, specific features in adolescence, gender differences, and the often-observed stability of body image (distortion), which may be present as a (trait) marker throughout the lifespan. The second part focuses on the organization of body image. The results of different studies on cognitive information processing are reviewed, the question of perceptual accuracy is addressed and the concepts of embodiment are examined. The third topic is body image distortion. First, the concept is contextualized along different continua, then discussed in a clinical sense along with the complexity of diagnostic methods, as well as the state and trait aspects of body image distortion. Orv Hetil. 2017; 158(19): 723–730.

Background:Olfactory disorders increase with age and often affect elderly people who have pre-dementia or dementia. Despite the frequent occurrence of olfactory changes at the early stages of neurodegenerative disorders such as Alzheimer's disease, olfactory disorders are rarely assessed in daily clinical practice, mainly due to a lack of standardised assessment tools. The aims of this review were to (1) summarise the existing literature on olfactory disorders in ageing populations and patients with neurodegenerative disorders; (2) present the strengths and weaknesses of current olfactory disorder assessment tools; and (3) discuss the benefits of developing specific olfactory tests for neurodegenerative diseases.Methods:A systematic review was performed of literature published between 2000 and 2015 addressing olfactory disorders in elderly people with or without Alzheimer's disease or other related disorders to identify the main tools currently used for olfactory disorder assessment.Results:Olfactory disorder assessment is a promising method for improving both the early and differential diagnosis of Alzheimer's disease. However, the current lack of consensus on which tests should be used does not permit the consistent integration of olfactory disorder assessment into clinical settings.Conclusion:Otolaryngologists are encouraged to use olfactory tests in older adults to help predict the development of neurodegenerative diseases. Olfactory tests should be specifically adapted to assess olfactory disorders in Alzheimer's disease patients.