Motion Perception Research Articles

Management of a Corneal Perforation Due to Resistant Peripheral Ulcerative Keratitis by Repeated Tectonic Patch Grafting Combined with Conjunctival Resection

Tectonic graft patching and conjunctival resection is one of the effective treatment modalities in especially resistant PUK patients with corneal perforation additional to topical and systemic immunosuppressive treatment. A 44-year-old female patient with a 10-year history of rheumatoid arthritis, was referred to our clinic with peripheric corneal perforation. Her visual acuity was at the level of hand movement perception in the left eye. Slit-lamp examination revealed medial PUK with corneal perforation. Tectonic patch grafting was performed. Two weeks later, because of small melting area at the inferior part of the graft with iris incarceration, an additional cornea-scleral graft transplantation was performed. Due to the immune nature of the PUK, limbal conjunctiva at the perforation site was also resected. Three months after the re-grafting, there was no recurrence. Best corrected visual acuity was 5/10 log MAR in the left eye.

Plasmon-Enhanced Optoelectronic Graded Neurons for Dual-Waveband Image Fusion and Motion Perception.

Motion recognition based on vision detectors requires the synchronous encoding and processing of temporal and spatial information in wide wavebands. Here, the dual-waveband sensitive optoelectronic synapses performing as graded neurons are reported for high-accuracy motion recognition and perception. Wedge-shaped nanostructures are designed and fabricated on molybdenum disulfide (MoS2) monolayers, leading to plasmon-enhanced wideband absorption across the visible to near-infrared spectral range. Due to the charge trapping and release at shallow trapping centers within the device channel, the optoelectronic graded neurons demonstrate remarkable photo-induced conductance plasticity at both 633 and 980nm wavelengths. A dynamic vision system consisting of 20 × 20 optoelectronic neurons demonstrates remarkable capabilities in the precise detection and perception of various motions. Moreover, neural network computing systems have been built as visual motion perceptron to identify target object movement. The recognition accuracy of dual-wavelength fused images for various motion trajectories has experienced a remarkable enhancement, transcending the previous level of less than 80% to impressive values exceeding 99%.

Retinal direction of motion is reliably transmitted to visual cortex through highly selective thalamocortical connections.

Motion perception is crucial to animal survival and effective environmental interactions. In mammals, detection of movement begins in the retina. Directionally selective (DS) retinal ganglion cells were first discovered in the rabbit eye,1 and they have since been found in mouse,2,3 cat,4 and monkey.5,6 These DS retinal neurons contact a small population of neurons in the visual thalamus (dorsal lateral geniculate nucleus [LGN]) that are highly DS.7,8,9,10 The primary visual cortex (V1) also contains DS neurons, but whether directional selectivity in V1 emerges de novo11,12,13 or is inherited from DS thalamic inputs14,15,16 remains unclear. We previously found that LGN-DS neurons generate strong and focal synaptic currents in rabbit V1, similar to those generated by LGN concentric cells.17 Thus, the synaptic drive generated by LGN-DS neurons in V1 is spatially well situated to influence the firing of layer 4 (L4) simple cells, most of which show strong directional selectivity.18 However, two important questions remain: do LGN-DS neurons synaptically target DS simple cells in L4, and, if so, do they contribute to the directional preferences of these V1 DS neurons? We used spike-train cross-correlation analysis of pairs of LGN-DS and L4 simple cells to address these questions. We found that LGN-DS neurons do target L4 DS simple cells and that the targeting is highly selective, largely following a simple set of "connectivity rules." We conclude that this highly selective thalamocortical connectivity of LGN-DS neurons contributes to the sharp directional selectivity of cortical simple cells.

Artificial neural network assisted omnidirectional strain sensors for human motion perception

Flexible resistance strain sensors gain tremendous attentions in emerging fields such as wearable sensing, electronic skins and human–machine interfaces due to its excellent stretchability and sensitivity. However, due to the coupling of strain along both principal and perpendicular axes, conventional uniaxial strain sensors face challenges in recognizing multi-directional strain which naturally occurs in practical applications. In this work, we present the omnidirectional strain sensors comprised of multiple-stacked oriented conductive layers and harness the artificial neural network (ANN) to assist recognizing strain information with high accuracy. Each conductive layer consists of a patterned multi-walled carbon nanotubes mixture coated on a soft substrate, exhibiting remarkable sensitivity with a gauge factor of 4.18 along the principal direction. When centrally aligning two or three layers along different directions, the assembled structures can monitor the multi-directional electronic resistance changes under deformations, enabling the recognition of both strain direction and amplitude. The ANN model used three-dimensional resistance data as input to perform a multi-class classification task, with strain amplitude and direction as the outputs. The hidden layers employed the ReLU activation function, while the output layer utilized the SoftMax activation function. The model was compiled with the sparse_categorical_crossentropy loss function and optimized using the Adam optimizer. Its performance was evaluated based on prediction accuracy. The strain prediction accuracy is above 98 % with the assistance of an ANN model. The triple-layer configuration can perceive the human wrist motions such as rotation and bending, exhibiting high potential in applications such as multidimensional wearable electronics.

A deep learning-enabled visual-inertial fusion method for human pose estimation in occluded human-robot collaborative assembly scenarios

In the context of human-centric smart manufacturing, human-robot collaboration (HRC) systems leverage the strengths of both humans and machines to achieve more flexible and efficient manufacturing. In particular, estimating and monitoring human motion status determines when and how the robots cooperate. However, the presence of occlusion in industrial settings seriously affects the performance of human pose estimation (HPE). Using more sensors can alleviate the occlusion issue, but it may cause additional computational costs and lower workers' comfort. To address this issue, this work proposes a visual-inertial fusion-based method for HPE in HRC, aiming to achieve accurate and robust estimation while minimizing the influence on human motion. A part-specific cross-modal fusion mechanism is designed to integrate spatial information provided by a monocular camera and six Inertial Measurement Units (IMUs). A multi-scale temporal module is developed to model the motion dependence between frames at different granularities. Our approach achieves 34.9 mm Mean Per Joint Positional Error (MPJPE) on the TotalCapture dataset and 53.9 mm on the 3DPW dataset, outperforming state-of-the-art visual-inertial fusion-based methods. Tests on a synthetic-occlusion dataset further validate the occlusion robustness of our network. Quantitative and qualitative experiments on a real assembly case verified the superiority and potential of our approach in HRC. It is expected that this work can be a reference for human motion perception in occluded HRC scenarios.

Perceptual-Motor Abilities and Reversal Frequency of Letters and Numbers in Children Diagnosed with Poor Reading Skills

Purpose: This paper investigated the visual–perceptual and visual–motor skills and the reversal frequency of letters and numbers that mirror one another in one hundred children aged 6–13 years diagnosed with poor reading skills. Methods: TVPS-4th, VMI-6th, and RFT were performed. Age and sex analysis was carried out. The impact of the eye movement patterns in the perceptual–motor skills and laterality–directionality concepts was also estimated to determine the relationship among tests to predict future results. Results: Most children scored between average and 3 stds below average on the motor VMI-6th test, while half of the participants scored between average and 2 stds below average on TVPS-4th. In the RFT, the majority scored between average and 1.5 stds below average. Participants scored higher on the spatial relationship subtest of the TVPS-4th and lower in the VMI-6th test (p<0.001). Statistically significant differences were found between the youngest and oldest participants on the TVPS-4th overall performance, as well as VD, FC and VFG skills (p<0.05). A strong relationship was found between the TVPS-4th and VMI-6th, (p<0.001). RFT results were different among all groups (p<0.05). The RFT was better related to the VMI-6th than TVPS-4th; however, it was statistically insignificant. The horizontal component of the DEM test was the best predictor for the TVPS-4th and ratio for the RFT, without attaining statistical significance. No sex differences were found. Conclusions: Results showed that children with poor reading skills exhibit perceptual–motor and reversal frequency difficulties, which are independent of the oculomotor performance. Considering that visual and motor processing are essential elements of the reading and writing process, their evaluation and treatment should be included as part of the multidisciplinary approach for children with poor reading skills. This would boost the general outcome and contribute to their academic achievement.

Hiding in plain sight: children with visual perceptual difficulties in schools

Cerebral visual impairment (CVI) is increasingly being recognized as a significant cause of visual difficulties in children, particularly those with typical visual acuity, who nonetheless struggle in educational settings. This narrative review aims to elucidate the nature and impact of visual perceptual difficulties (VPD) associated with CVI in school-aged children, who often remain undiagnosed due to the current erroneous focus on visual acuity as a required diagnostic criterion for CVI. The review synthesizes findings from recent studies, highlighting that up to 3.4% of children in mainstream schools and a higher percentage in special educational settings may experience VPD, which significantly impacts upon their learning and development. The manifestations of VPDs, such as difficulties in motion perception, recognition, and visuospatial processing, are often subtle and can thus be overlooked, leading to misconceptions about the origins of the affected child’s abilities and behaviors. The review also discusses the challenges in current diagnostic processes, emphasizing the need for comprehensive history taking and assessments that go beyond standard visual acuity tests. It proposes a multi-faceted approach to identification and support, incorporating both clinical assessments and teacher/parental observations, to better address the needs of affected children. Furthermore, this paper advocates for the inclusion of VPDs in the International Classification of Diseases (ICD 11) to ensure children with these visual issues receive appropriate educational support. By integrating lived experiences of individuals with CVI and the latest research findings, this review underscores the urgent need for awareness and tailored educational strategies designed to support children with VPDs. The findings suggest that without such recognition and intervention, many children with VPDs will continue to “hide in plain sight,” facing unnecessary challenges in their educational and social development. The review concludes with recommendations for policy changes and future research directions to improve the identification, classification, and support of children with VPDs within the educational system.

Tracking cortical entrainment to stages of optic-flow processing

In human visual processing, information from the visual field passes through numerous transformations before perceptual attributes such as motion are derived. Determining the sequence of transforms involved in the perception of visual motion has been an active field since the 1940s. One plausible family of models are the spatiotemporal energy models, based on computations of motion energy computed from the spatiotemporal features the visual field. One of the most venerated is that of Heeger (1988), which hypotheses that motion is estimated by matching the predicted spatiotemporal energy in frequency space. In this study, we investigate the plausibility of Heeger’s model by testing for evidence of cortical entrainment to its components. Entrainment of cortical activity to these components was estimated using measurements of electro- and magnetoencephalographic (EMEG) activity, recorded while healthy subjects watched videos of dots moving left and right across their visual field. We find entrainment to several components of Heeger’s model bilaterally in occipital lobe regions, including representations of motion energy at a latency of 80 ms, overall velocity at 95 ms, and acceleration at 130 ms. We find little evidence of entrainment to displacement. We contrast Heeger’s biologically inspired model with alternative baseline models, finding that Heeger’s model provides a closer fit to the observed data. These results help shed light on the processes through which perception of motion arises in the visual processing stream.

Localization of Turn Points in the Rhythmic Movement of Sound Image

The localization of start and turn points in rhythmic sound movement created through the modeling of binaural beats (BB) was investigated. The BB-modeled broadband stimuli consisted of stationary initial and final segments with a section of cyclic motion between them. Spatial effects were induced by changes in the interaural time difference (ITD). During the experiment, subjects assessed the position of the movement trajectory ends or the position of reference points using a graphic tablet. It was discovered that the perception of rhythmic movement of the sound image was significantly influenced by the integrative ability of the binaural auditory system. The results indicated that with instantaneous switching between stationary segments, the perceived positions of the trajectory ends (start point and turn point) matched the positions of the reference points. Conversely, the smooth movement between the same extreme values showed a displacement of the trajectory ends: the turn points were localized further from the reference points compared to the start points, at all trajectory positions in space. Localization of the trajectory end crucially depended on the time that the sound had stayed near the turning point. These patterns were expressed stronger in the central area of the acoustic space compared to the periphery.

Evaluating Visual Perception of Object Motion in Dynamic Environments

Precisely understanding how objects move in 3D is essential for broad scenarios such as video editing, gaming, driving, and athletics. With screen-displayed computer graphics content, users only perceive limited cues to judge the object motion from the on-screen optical flow. Conventionally, visual perception is studied with stationary settings and singular objects. However, in practical applications, we---the observer---also move within complex scenes. Therefore, we must extract object motion from a combined optical flow displayed on screen, which can often lead to mis-estimations due to perceptual ambiguities. We measure and model observers' perceptual accuracy of object motions in dynamic 3D environments, a universal but under-investigated scenario in computer graphics applications. We design and employ a crowdsourcing-based psychophysical study, quantifying the relationships among patterns of scene dynamics and content, and the resulting perceptual judgments of object motion direction. The acquired psychophysical data underpins a model for generalized conditions. We then demonstrate the model's guidance ability to significantly enhance users' understanding of task object motion in gaming and animation design. With applications in measuring and compensating for object motion errors in video and rendering, we hope the research establishes a new frontier for understanding and mitigating perceptual errors caused by the gap between screen-displayed graphics and the physical world.

Visual attention modulates mu suppression during biological motion perception in autistic individuals.

There has been a lot of controversy regarding mirror neuron function in autism spectrum disorder (ASD), in particular during the observation of biological motions (BM). Here, we directly explored the link between visual attention and brain activity in terms of mu suppression, by simultaneously recording eye-tracking and EEGs during BM tasks. Nineteen autistic children (15 boys, mean age = 11.57 ± 4.28 years) and 19 age-matched neurotypical (NT) children (15 boys, mean age = 11.68 ± 5.22 years) participated in the study. Each participant's eye movement and EEG were simultaneously recorded while watching four BM stimuli (walking, cartwheeling, free-throwing and underarm throwing) and a scrambled condition. Mu (8-13 Hz) suppression index (SI) for central regions was calculated. Fixation counts and percent of fixation time were calculated as indices of eye movements. EEG results revealed significant mu suppressions in the central region in both groups for all BM actions. Eye-tracking results showed that NT children had greater fixation counts and a higher percentage of fixation time than autistic children, indicating greater overall visual attention to BM. Notably, correlational analyses for both groups further revealed that individuals' fixation time and fixation counts were negatively correlated with the mu suppression index for all actions, indicating a strong association between visual attention and mu SI in the central region. Our findings suggest a critical role of visual attention in interpreting mu suppression during action perception in autism.

Causal inference predicts the transition from integration to segmentation in motion perception

Motion provides a powerful sensory cue for segmenting a visual scene into objects and inferring the causal relationships between objects. Fundamental mechanisms involved in this process are the integration and segmentation of local motion signals. However, the computations that govern whether local motion signals are perceptually integrated or segmented remain unclear. Hierarchical Bayesian causal inference has recently been proposed as a model for these computations, yet a hallmark prediction of the model – its dependency on sensory uncertainty – has remained untested. We used a recently developed hierarchical stimulus configuration to measure how human subjects integrate or segment local motion signals while manipulating motion coherence to control sensory uncertainty. We found that (a) the perceptual transition from motion integration to segmentation shifts with sensory uncertainty, and (b) that perceptual variability is maximal around this transition point. Both findings were predicted by the model and challenge conventional interpretations of motion repulsion effects.

Aging and the visual perception of rigid and nonrigid motion

Nonrigid forms of motion are commonplace in everyday life. Given previously documented age-related deteriorations in various tasks involving motion (discriminating speed, identifying motion direction, etc.), an experiment was conducted to evaluate the potential effect of age upon the visual ability to detect rigid and nonrigid object motion. Thirty younger and older observers participated in the experiment (mean ages were 19.9 and 75.8 years, respectively). As has been done multiple times in the past, the individual motions of object vertices were manipulated to simulate either rigid motion (rotation in depth, with or without precession) or two different types of nonrigid motion (also rotation in depth with or without precession, but with added object deformation). In confirmation of previous research, there were large effects of nonrigid motion type and precession upon the ability to differentiate between rigid and nonrigid object motion. There was also a large effect of age, such that the discrimination performance of the younger observers was 49.6% higher than that exhibited by the older observers. In this first ever study of aging and nonrigid object motion perception, we thus find that aging is associated with a substantial impairment in the ability to visually perceive object nonrigidity.

Sex differences in the human brain related to visual motion perception

BackgroundPrevious studies have found that the temporal duration required for males to perceive visual motion direction is significantly shorter than that for females. However, the neural correlates of such shortened duration perception remain yet unclear. Given that motion perception is primarily associated with the neural activity of the middle temporal visual complex (MT+), we here test the novel hypothesis that the neural mechanism of these behavioral sex differences is mainly related to the MT+ region.MethodsWe utilized ultra-high field (UHF) MRI to investigate sex differences in the MT+ brain region. A total of 95 subjects (48 females) participated in two separate studies. Cohort 1, consisting of 33 subjects (16 females), completed task-fMRI (drafting grating stimuli) experiment. Cohort 2, comprising 62 subjects (32 females), engaged in a psychophysical experiment measuring motion perception along different temporal thresholds as well as conducting structural and functional MRI scanning of MT+.ResultsOur findings show pronounced sex differences in major brain parameters within the left MT+ (but not the right MT+, i.e., laterality). In particular, males demonstrate (i) larger gray matter volume (GMV) and higher brain’s spontaneous activity at the fastest infra-slow frequency band in the left MT+; and (ii) stronger functional connectivity between the left MT+ and the left centromedial amygdala (CM). Meanwhile, both female and male participants exhibited comparable correlations between motion perception ability and the multimodal imaging indexes of the MT+ region, i.e., larger GMV, higher brain’s spontaneous activity, and faster motion discrimination.ConclusionsOur findings reveal sex differences of imaging indicators of structure and function in the MT+ region, which also relate to the temporal threshold of motion discrimination. Overall, these results show how behavioral sex differences in visual motion perception are generated, and advocate considering sex as a crucial biological variable in both human brain and behavioral research.

Obstetric Brachial Plexus Palsy and Functional Implications: Which Joint in the Upper Extremity Is More Closely Associated?

Background and Objectives: The objective of this study is to examine the correlation between the active range of motion (ROM) of the affected upper extremity and functional capacity in children with Obstetric Brachial Plexus Palsy (OBPP) who have undergone the modified Hoffer tendon transfer technique. Materials and Methods: The study cohort comprised 52 children with OBPP, aged 4-14 years, who had undergone a shoulder tendon transfer. The ROM was quantified using a goniometer, while functionality was evaluated through the administration of the Brachial Plexus Outcome Measure (BPOM). Results: The study identified significant correlations between the shoulder ROM and the Brachial Plexus Outcome Measure (BPOM). Specifically, shoulder flexion (p = 0.017; r = 0.351) was positively associated with shoulder functionality, while shoulder internal rotation (p = 0.001; r = 0.481) was linked to appearance scores. A significant negative relationship was observed between elbow extension (p < 0.001; r = -0.512) and elbow and forearm activities. Conclusions: The study highlights the necessity of assessing both joint range of motion and body perception for effective treatment and follow-up, to improve the functionality and quality of life for children with OBPP.

Human Perception of the Emotional Expressions of Humanoid Robot Body Movements: Evidence from Survey and Eye-Tracking Measurements.

The emotional expression of body movement, which is an aspect of emotional communication between humans, has not been considered enough in the field of human-robot interactions (HRIs). This paper explores human perceptions of the emotional expressions of humanoid robot body movements to study the emotional design of the bodily expressions of robots and the characteristics of the human perception of these emotional body movements. Six categories of emotional behaviors, including happiness, anger, sadness, surprise, fear, and disgust, were designed by imitating human emotional body movements, and they were implemented on a Yanshee robot. A total of 135 participants were recruited for questionnaires and eye-tracking measurements. Statistical methods, including K-means clustering, repeated analysis of variance (ANOVA), Friedman's ANOVA, and Spearman's correlation test, were used to analyze the data. According to the statistical results of emotional categories, intensities, and arousals perceived by humans, a guide to grading the designed robot's bodily expressions of emotion is created. By combining this guide with certain objective analyses, such as fixation and trajectory of eye movements, the characteristics of human perception, including the perceived differences between happiness and negative emotions and the trends of eye movements for different emotional categories, are described. This study not only illustrates subjective and objective evidence that humans can perceive robot bodily expressions of emotions through only vision but also provides helpful guidance for designing appropriate emotional bodily expressions in HRIs.

Detecting biological motion signals in human and monkey superior colliculus: a subcortical-cortical pathway for biological motion perception.

Most vertebrates, including humans, are highly adept at detecting and encoding biological motion, even when it is portrayed by just a few point lights attached to the head and major joints. However, the function of subcortical regions in biological motion perception has been scarcely explored. Here, we investigate the role of the superior colliculus in local biological motion processing. Using high-field (3 T) and ultra-high-field (7 T) functional magnetic resonance imaging, we record the neural responses of the superior colliculus to scrambled point-light walkers (with local kinematics retained) in both humans and male macaque monkeys. Results show that the superior colliculus, especially the superficial layers, selectively responds to local biological motion. Furthermore, dynamic causal modeling analysis reveals a subcortical-cortical functional pathway that transmits local biological motion signals from the superior colliculus via the middle temporal visual complex to the posterior superior temporal sulcus in the human brain. These findings suggest the existence of a cross-species mechanism in the superior colliculus that facilitates the detection of local biological motion at the early stage of the visual processing stream.

Attentional focus modulates physiological response to arousal in a competitive putting task.

Attentional focus during the execution of perceptual motor tasks has been shown to affect performance outcomes. The purpose of this study is to assess the physiological changes prompted by attentional focus in various levels of stress. Thirty-six healthy young males and females were randomized into groups and directed on attentional focus in a staged putting competition scenario intended to elicit competitive anxiety. External focus groups experienced less internal workload at all arousal levels and preserved heart rate variability measures when audiovisual distraction was introduced.

Rigid propagation of visual motion in the insect’s neural system

In the pursuit of developing an efficient artificial visual system for visual motion detection, researchers find inspiration from the visual motion-sensitive neural pathways in the insect’s neural system. Although multiple proposed neural computational models exhibit significant performance aligned with those observed from insects, the mathematical basis for how these models characterize the sensitivity of visual neurons to corresponding motion patterns remains to be elucidated. To fill this research gap, this study originally proposed that the rigid propagation of visual motion is an essential mathematical property of the models for the insect’s visual neural system, meaning that the dynamics of the model output remain consistent with the visual motion dynamics reflected in the input. To verify this property, this study uses the small target motion detector (STMD) neural pathway — one of the visual motion-sensitive pathways in the insect’s neural system — as an exemplar, rigorously demonstrating that the dynamics of translational visual motion are rigidly propagated through the encoding of retinal measurements in STMD computational models. Numerical experiment results further substantiate the proposed property of STMD models. This study offers a novel theoretical framework for exploring the nature of the visual motion perception underlying the insect’s visual neural system and brings an innovative perspective to the broader research field of insect visual motion perception and artificial visual systems.

Enhanced visual contrast suppression during peak psilocybin effects: Psychophysical results from a pilot randomized controlled trial.

In visual perception, an effect known as surround suppression occurs wherein the apparent contrast of a center stimulus is reduced when it is presented within a higher-contrast surrounding stimulus. Many key aspects of visual perception involve surround suppression, yet the neuromodulatory processes involved remain unclear. Psilocybin is a serotonergic psychedelic compound known for its robust effects on visual perception, particularly texture, color, object, and motion perception. We asked whether surround suppression is altered under peak effects of psilocybin. Using a contrast-matching task with different center-surround stimulus configurations, we measured surround suppression after 25mg of psilocybin compared with placebo (100mg niacin). Data on harms were collected, and no serious adverse events were reported. After taking psilocybin, participants (n = 6) reported stronger surround suppression of perceived contrast compared to placebo. Furthermore, we found that the intensity of subjective psychedelic visuals induced by psilocybin correlated positively with the magnitude of surround suppression. We note the potential relevance of our findings for the field of psychiatry, given that studies have demonstrated weakened visual surround suppression in both major depressive disorder and schizophrenia. Our findings are thus relevant to understanding the visual effects of psilocybin, and the potential mechanisms of visual disruption in mental health disorders.