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Introduction: Augmented Reality (AR) systems are systems in which users view and interact with virtual objects overlaying the real world. AR systems are used across a variety of disciplines, i.e., games, medicine, and education to name a few. Optical See-Through (OST) AR displays allow users to perceive the real world directly by combining computer-generated imagery overlaying the real world. While perception of depth and visibility of objects is a widely studied field, we wanted to observe how color, luminance, and movement of an object interacted with each other as well as external luminance in OST AR devices. Little research has been done regarding the issues around the effect of virtual objects' parameters on depth perception, external lighting, and the effect of an object's mobility on this depth perception. Methods: We aim to perform an analysis of the effects of motion cues, color, and luminance on depth estimation of AR objects overlaying the real world with OST displays. We perform two experiments, differing in environmental lighting conditions (287 lux and 156 lux), and analyze the effects and differences on depth and speed perceptions. Results: We have found that while stationary objects follow previous research with regards to depth perception, motion and both object and environmental luminance play a factor in this perception. Discussion: These results will be significantly useful for developers to account for depth estimation issues that may arise in AR environments. Awareness of the different effects of speed and environmental illuminance on depth perception can be utilized when performing AR or MR applications where precision matters. [ABSTRACT FROM AUTHOR]

Introduction: Augmented Reality (AR) systems are systems in which users view and interact with virtual objects overlaying the real world. AR systems are used across a variety of disciplines, i.e., games, medicine, and education to name a few. Optical See-Through (OST) AR displays allow users to perceive the real world directly by combining computer-generated imagery overlaying the real world. While perception of depth and visibility of objects is a widely studied field, we wanted to observe how color, luminance, and movement of an object interacted with each other as well as external luminance in OST AR devices. Little research has been done regarding the issues around the effect of virtual objects’ parameters on depth perception, external lighting, and the effect of an object’s mobility on this depth perception.Methods: We aim to perform an analysis of the effects of motion cues, color, and luminance on depth estimation of AR objects overlaying the real world with OST displays. We perform two experiments, differing in environmental lighting conditions (287 lux and 156 lux), and analyze the effects and differences on depth and speed perceptions.Results: We have found that while stationary objects follow previous research with regards to depth perception, motion and both object and environmental luminance play a factor in this perception.Discussion: These results will be significantly useful for developers to account for depth estimation issues that may arise in AR environments. Awareness of the different effects of speed and environmental illuminance on depth perception can be utilized when performing AR or MR applications where precision matters.

Animals in groups integrate social with directly gathered information about the environment to guide decisions regarding reproduction, foraging, and defence against predatory threats. In the context of predation, usage of social information has acute fitness benefits, aiding the detection of predators, the mounting of concerted defensive responses, or allowing the inference of safety, permitting other beneficial behaviors, such as foraging for food. We previously showed that Drosophila melanogaster exposed to an inescapable visual threat use freezing by surrounding flies as a cue of danger and movement resumption as a cue of safety. Moreover, group responses were primarily guided by the safety cues, resulting in a net social buffering effect, i.e., a graded decrease in freezing behavior with increasing group sizes, similar to other animals. Whether and how different threat levels affect the use of social cues to guide defense responses remains elusive. Here, we investigated this issue by exposing flies individually and in groups to two threat imminences using looms of different speeds. We showed that freezing responses are stronger to the faster looms regardless of social condition. However, social buffering was stronger for groups exposed to the fast looms, such that the increase in freezing caused by the higher threat was less prominent in flies tested in groups than those tested individually. Through artificial control of movement, we created groups composed of moving and freezing flies and by varying group composition, we titrated the motion cues that surrounding flies produce, which were held constant across threat levels. We found that the same level of safety motion cues had a bigger weight on the flies’ decisions when these were exposed to the higher threat, thus overriding differences in perceived threat levels. These findings shed light on the “safety in numbers” effect, revealing the modulation of the saliency of social safety cues across threat intensities, a possible mechanism to regulate costly defensive responses.

The ability to make accurate social inferences makes humans able to navigate and act in their social environment effortlessly. Converging evidence shows that motion is one of the most informative cues in shaping the perception of social interactions. However, the scarcity of parameterized generative models for the generation of highly-controlled stimuli has slowed down both the identification of the most critical motion features and the understanding of the computational mechanisms underlying their extraction and processing from rich visual inputs. In this work, we introduce a novel generative model for the automatic generation of an arbitrarily large number of videos of socially interacting agents for comprehensive studies of social perception. The proposed framework, validated with three psychophysical experiments, allows generating as many as 15 distinct interaction classes. The model builds on classical dynamical system models of biological navigation and is able to generate visual stimuli that are parametrically controlled and representative of a heterogeneous set of social interaction classes. The proposed method represents thus an important tool for experiments aimed at unveiling the computational mechanisms mediating the perception of social interactions. The ability to generate highly-controlled stimuli makes the model valuable not only to conduct behavioral and neuroimaging studies, but also to develop and validate neural models of social inference, and machine vision systems for the automatic recognition of social interactions. In fact, contrasting human and model responses to a heterogeneous set of highly-controlled stimuli can help to identify critical computational steps in the processing of social interaction stimuli.

The ability to make accurate social inferences makes humans able to navigate and act in their social environment effortlessly. Converging evidence shows that motion is one of the most informative cues in shaping the perception of social interactions. However, the scarcity of parameterized generative models for the generation of highly-controlled stimuli has slowed down both the identification of the most critical motion features and the understanding of the computational mechanisms underlying their extraction and processing from rich visual inputs. In this work, we introduce a novel generative model for the automatic generation of an arbitrarily large number of videos of socially interacting agents for comprehensive studies of social perception. The proposed framework, validated with three psychophysical experiments, allows generating as many as 15 distinct interaction classes. The model builds on classical dynamical system models of biological navigation and is able to generate visual stimuli that are parametrically controlled and representative of a heterogeneous set of social interaction classes. The proposed method represents thus an important tool for experiments aimed at unveiling the computational mechanisms mediating the perception of social interactions. The ability to generate highly-controlled stimuli makes the model valuable not only to conduct behavioral and neuroimaging studies, but also to develop and validate neural models of social inference, and machine vision systems for the automatic recognition of social interactions. In fact, contrasting human and model responses to a heterogeneous set of highly-controlled stimuli can help to identify critical computational steps in the processing of social interaction stimuli. [ABSTRACT FROM AUTHOR]

Multiple object tracking sets the foundation for many intelligent video applications. The authors present a novel tracking solution using the ability of recurrent neural networks to effectively model complex temporal dynamics between objects irrespective of appearances, pose, occlusions, and illumination. For online tracking, a real-time and accurate association of objects with active tracks poses the major algorithmic challenge. Additionally, re-entry of objects should also be correctly resolved. They follow tracking-by-detection methodology using hierarchical long short term memory (LSTM) network structure for modelling the motion dynamics between objects by learning the fusion of appearance and motion cues. Existing works capture object's perspective for tracking within the detected bounding boxes. They also incorporate object instance segments for track modelling by applying the maskRCNN detector. They present a novel motion coding scheme that anchors the LSTM structure to effectively model the motion and relative position between objects in a single representation scheme. The proposed motion representation and deep features representing objects appearances are fused in an embedded space learned by the hierarchical LSTM structure for predicting the object to track association. The authors present experimental validation of the proposed approach on multiple object tracking challenge datasets and demonstrate that their solution naturally deals with major tracking challenges under all uncertainties.

Multiple object tracking sets the foundation for many intelligent video applications. The authors present a novel tracking solution using the ability of recurrent neural networks to effectively model complex temporal dynamics between objects irrespective of appearances, pose, occlusions, and illumination. For online tracking, a real-time and accurate association of objects with active tracks poses the major algorithmic challenge. Additionally, re-entry of objects should also be correctly resolved. They follow tracking-by-detection methodology using hierarchical long short term memory (LSTM) network structure for modelling the motion dynamics between objects by learning the fusion of appearance and motion cues. Existing works capture object's perspective for tracking within the detected bounding boxes. They also incorporate object instance segments for track modelling by applying the maskRCNN detector. They present a novel motion coding scheme that anchors the LSTM structure to effectively model the motion and relative position between objects in a single representation scheme. The proposed motion representation and deep features representing objects appearances are fused in an embedded space learned by the hierarchical LSTM structure for predicting the object to track association. The authors present experimental validation of the proposed approach on multiple object tracking challenge datasets and demonstrate that their solution naturally deals with major tracking challenges under all uncertainties. [ABSTRACT FROM AUTHOR]

The successful portrayal of personality in digital characters improves communication and immersion. Current research focuses on expressing personality through modifying animations using heuristic rules or data-driven models. While studies suggest motion style highly influences the apparent personality, the role of appearance can be similarly essential. This work analyzes the influence of movement and appearance on the perceived personality of short videos altered by motion transfer networks. We label the personalities in conference video clips with a user study to determine the samples that best represent the Five-Factor model's high, neutral, and low traits. We alter these videos using the Thin-Plate Spline Motion Model, utilizing the selected samples as the source and driving inputs. We follow five different cases to study the influence of motion and appearance on personality perception. Our comparative study reveals that motion and appearance influence different factors: motion strongly affects perceived extraversion, and appearance helps convey agreeableness and neuroticism. [Display omitted] • We analyze personality expression in videos generated by motion transfer networks. • We examine the effect of motion and appearance on personality via user studies. • Motion transfer can control perceived extroversion and openness. • Different appearances can be used for expressing agreeableness and neuroticism. • We observe that altering conscientiousness is difficult in short sequences. [ABSTRACT FROM AUTHOR]

Facial biometric systems are vulnerable to fraudulent access attempts by presenting photographs or videos of a valid user in front of the sensor also known as “spoofing attacks”. Multiple protection measures have been proposed but limited attention has been dedicated to exclusive motion-based countermeasures since the arrival of video and mask attacks. A novel motion-based countermeasure which exploits natural and unnatural motion cues is presented. The proposed method takes advantage of the Conditional Local Neural Fields (CLNF) face tracking algorithm to extract rigid and non-rigid face motions. Similarly to the bag-of-words feature encoding, a vocabulary of motion sequences is constructed to derive discriminant mid-level motion features using the Fisher vector framework. Extensive experiments are conducted on ReplayAttack-DB, CASIA-FASD and MSU-MFSD databases. Complementary experiments on rigid mask attacks from the 3DMAD public database are also conducted and generalization issues are investigated via cross-database evaluation in particular. [ABSTRACT FROM AUTHOR]

Using appropriate antipredatory responses is crucial for survival. While slowing down reduces the chances of being detected from distant predators, fleeing away is advantageous in front of an approaching predator. Whether appropriate responses depend on experience with moving objects is still an open question. To clarify whether adopting appropriate fleeing or freezing responses requires previous experience, we investigated responses of chicks naive to movement. When exposed to the moving cues mimicking an approaching predator (a rapidly expanding, looming stimulus), chicks displayed a fast escape response. In contrast, when presented with a distal threat (a small stimulus sweeping overhead) they decreased their speed, a maneuver useful to avoid detection. The fast expansion of the stimulus toward the subject, rather than its size per se or change in luminance, triggered the escape response. These results show that young animals, in the absence of previous experience, can use motion cues to select the appropriate responses to different threats. The adaptive needs of young preys are thus matched by spontaneous defensive mechanisms that do not require learning. [ABSTRACT FROM AUTHOR]

The aim of this review is to explain the functional significance of mantis peering behaviour from an entomological perspective. First the morphological and optical features of the mantis compound eye that are important for spatial vision are described. The possibility that praying-mantises use binocular retinal disparity (stereopsis) and other alternative visual cues for determining distance in prey capture, are discussed. The primary focus of the review is the importance of peering movements for estimating the distance to stationary objects. Here the following aspects are examined: (1) Direct evidence via object manipulation experiments of absolute distance estimation with the aid of self-induced retinal image motion; (2) the mechanism of absolute distance estimation (with the interaction of visual and proprioceptive information); (3) the range of absolute and relative distance estimation; (4) the influence of target object features on distance estimation; and (5) the relationship between peering behaviour and habitat structures, based on results of studies on three species of mantis.

Vehicle and pedestrian tracking is a key component for vision-based safety analysis which can use motion and appearance cues of road users. Since appearance-based detectors generate false alarms and provide lower speed, motion-based detectors are preferred but they work poorly when pedestrians or vehicles stop due to traffic signals. In this paper, a tracking system is proposed to track waiting and moving road users by fusion of motion and appearance cues at detection level. The enhanced optical flow tracker handles the partial occlusion problem, and it cooperates with the detection module to provide long-term tracks of vehicles and pedestrians. The system evaluation shows 13% and 43% improvement in tracking of vehicles and pedestrians respectively, and finally heat-maps show benefits of using the proposed system through the visual depiction of intersection usage. [ABSTRACT FROM AUTHOR]

People read dominance, trustworthiness and competence into the faces of politicians but do they also perceive such social qualities in other nonverbal cues? We transferred the body movements of politicians giving a speech onto animated stick-figures and presented these stimuli to participants in a rating-experiment. Analyses revealed single body postures of maximal expansiveness as strong predictors of perceived dominance. Also, stick-figures producing expansive movements as well as a great number of movements throughout the encoded sequences were judged high on dominance and low on trustworthiness. In a second step we divided our sample into speakers from the opposition parties and speakers that were part of the government as well as into male and female speakers. Male speakers from the opposition were rated higher on dominance but lower on trustworthiness than speakers from all other groups. In conclusion, people use simple cues to make equally simple social categorizations. Moreover, the party status of male politicians seems to become visible in their body motion. [ABSTRACT FROM AUTHOR]

• Unlimited angular motion cues via a spherical motion platform reduce motion sickness. • Cue conflict is directly measured by the mismatch between visual and motion cues. • Cue mismatches in pitch angle and yaw velocity correlate with motion sickness. Simulator sickness is a crucial concern undermining several benefits of simulator training, such as a realistic environment, low costs, and safe practice of emergencies. This study investigated the effects of unbounded angular motions and visual-vestibular cue discrepancies on simulator sickness for flight simulator training. Human subject experiments with 36 participants demonstrated that simulator sickness, measured by questionnaires and physiological signals, was significantly decreased by offering both motion and visual cues rather than visual signals alone (p < 0.05). Specifically, nausea (without motion = 54.59, with motion = 31.27; p = 0.036) and disorientation scores (without motion = 81.20, with motion = 44.08; p = 0.028) significantly decreased when both motion and visual signals were present. Furthermore, the experimental results showed a significant correlation between simulator sickness and visual-vestibular cue mismatches, particularly for the angular velocity along the z-axis (r = 0.110, p = 0.04). The pitch angle discrepancy (r = 0.156, p = 0.004) between the visual and motion cues was significantly correlated with the sickness severity, unlike the roll angle disparity (r = −0.009, p = 0.871). The results from this study can be explored for flight training operations using motion simulators to minimize or eliminate simulator sickness. [ABSTRACT FROM AUTHOR]

The aviation community relies heavily on flight simulators as a fundamental tool for research, pilot training and development of any new aircraft design. The goal of the present paper is to provide a review on how effective ground simulation is as an assessment tool for unmasking adverse Aircraft-and-Rotorcraft Pilot Couplings (APC/RPC). Although it is generally believed that simulators are not reliable in revealing the existence of A/RPC tendencies, the paper demonstrates that a proper selection of high-gain tasks combined with appropriate motion and visual cueing can reveal negative features of a particular aircraft that may lead to A/RPC. The paper discusses new methods for real-time A/RPC detection that can be used as a tool for unmasking adverse A/RPC. Although flight simulators will not achieve the level of reality of in-flight testing, exposing A/RPC tendencies in the simulator may be the only convenient safe place to evaluate the wide range of conditions that could produce hazardous A/RPC events. [ABSTRACT FROM AUTHOR]

In referential communication, gaze is often interpreted as a social cue that facilitates comprehension and enables word learning. Here we investigated the degree to which head turning facilitates gaze following. We presented participants with static pictures of a man looking at a target object in a first and third block of trials (pre- and post-intervention), while they saw short videos of the same man turning towards the target in the second block of trials (intervention). In Experiment 1, newly sighted individuals (treated for congenital cataracts; N = 8) benefited from the motion cues, both when comparing their initial performance with static gaze cues to their performance with dynamic head turning, and their performance with static cues before and after the videos. In Experiment 2, neurotypical school children (ages 5–10 years; N = 90) and adults (N = 30) also revealed improved performance with motion cues, although most participants had started to follow the static gaze cues before they saw the videos. Our results confirm that head turning is an effective social cue when interpreting new words, offering new insights for a pathways approach to development. [ABSTRACT FROM AUTHOR]

Research on facial expressions in individuals with Down syndrome (DS) has been conducted using photographs. Our goal was to examine the effect of motion on perception of emotional expressions. Adults with DS, adults with typical development matched for chronological age (CA), and children with typical development matched for developmental age (DA) viewed photographs and video clips of facial expressions of: happy, sad, mad, and scared. The odds of accurate identification of facial expressions were 2.7 times greater for video clips compared with photographs. The odds of accurate identification of expressions of mad and scared were greater for video clips compared with photographs. The odds of accurate identification of expressions of mad and sad were greater for adults but did not differ between adults with DS and children. Adults with DS demonstrated the lowest accuracy for recognition of scared. These results support the importance of motion cues in evaluating the social skills of individuals with DS. [ABSTRACT FROM AUTHOR]

Abstract: Sounds with increasing intensity can act as intrinsic warning cues by signalling that the sound source is approaching. However, intensity change is not always the dominant motion cue to a moving sound, and the effects of simple rising intensity sounds versus sounds with full three dimensional motion cues have not yet been directly compared. Here, we examined skin conductance responses, phasic alertness, and perceptual and explicit emotional ratings in response to approaching and receding sounds characterised either by full motion cues or by intensity change only. We found a stronger approach/recede effect in sounds with full motion cues for skin conductance response amplitude, suggesting sustained mobilisation of resources due to their greater saliency. Otherwise, the approach/recede effect was comparable in sounds with and without full motion cues. Overall, approaching sounds elicited greater skin conductance responses and phasic alertness, and loudness change was estimated higher. Also, they were rated as more unpleasant, potent, arousing and intense, and the probability of such sounds to signal a salient event or threat was rated higher. Several of these effects were modulated by sex. In summary, this study supports the suggestion that intensity change is the dominant motion cue mediating the effects of approaching sound sources, thus clarifying the interpretation of previous studies using such stimuli. Explicit emotional appraisal of such sounds shows a strong directional asymmetry and thus may reflect their implicit warning properties. [Copyright &y& Elsevier]

The need for a movement response may often be preceded by some advance information regarding direction or extent. We examined the ability of individuals with Developmental Coordination Disorder (DCD) to organise a movement in response to advance information. Pre-cues were presented and varied in the extent to which they indicated the response target. Both eye movement latencies and hand movements were measured. In the absence of pre-cues, individuals with DCD were as fast in initial hand movements as the typically developing (TD) participants, but were less efficient at correcting initial directional errors. A major difference was seen in the degree to which each group could use advance pre-cue information. TD participants were able to use pre-cue information to refine their actions. For the individuals with DCD this was only effective if there was no ambiguity in the advance cue and they had particular difficulty in using predictive motion cues. There were no differences in the speed of gaze responses which excluded an explanation relating to the dynamic allocation of attention. Individuals with DCD continued to rely on the slower strategy of fixating the target prior to initiating a hand movement, rather than using advance information to set initial movement parameters. [ABSTRACT FROM AUTHOR]

Joint attention is one of the most important cognitive functions for the emergence of communication not only between humans, but also between humans and robots. In previous work, we have demonstrated how a robot can acquire primary joint attention behavior (gaze following) without external evaluation. However, this method needs the human to tell the robot when to shift its gaze. This paper presents a method that does not need such a constraint by introducing an attention selector based on a measure consisting of saliencies of object features and motion cues. In order to realize natural interaction, a self-organizing map for real-time face pattern separation and contingency learning for gaze following without external evaluation are utilized. The attention selector controls the robot gaze to switch often from the human face to an object and vice versa, and pairs of a face pattern and a gaze motor command are input to the contingency learning. The motion cues are expected to reduce the number of incorrect training data pairs due to the asynchronous interaction that affects the convergence of the contingency learning. The experimental result shows that gaze shift utilizing motion cues enables a robot to synchronize its own motion with human motion and to learn joint attention efficiently in about 20 min. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that speed cues are used to haptically identify changes in the curvature of the hand's trajectory. Subjects grasped the handle of a robotically-controlled manipulandum that was moved in the horizontal plane along various elliptical arcs following one of three different speed profiles. In one profile, a circular arc was traced at a constant speed whereas in the other two speed was constant for ellipses whose aspect ratios differed from unity. A two-alternative forced choice procedure was used to identify the ellipse that was sensed to be circular in each of the three experimental conditions. In unconstrained movements, speed varies with the radius of curvature. If speed cues are used to identify curvature during passive movements, one would expect that subjects responses should be biased towards the ellipse traced at a constant speed. The results did not support this hypothesis, indicating that speed cues are not a major contributor in the haptic sensing of shape. [ABSTRACT FROM AUTHOR]