How spotting technique affects dizziness and postural stability after full-body rotations in dancers.

Consecutive longitudinal axis rotations are very common in dance, ranging from head spins in break dance to pirouettes in ballet. They pose a rather formidable perceptuomotor challenge - and hence form an interesting window into human motor behaviour - yet they have been scarcely studied. In the present study, we investigated dancers' dizziness and postural stability after consecutive rotations. Rotations were performed actively or undergone passively, either with or without the use of a spotting technique in such an order that all 24 ordering options were offered at least once and not more than twice. Thirty-four dancers trained in ballet and/or contemporary dance (aged 27.2 ± 5.1 years) with a mean dance experience of 14.2 ± 7.1 years actively performed 14 revolutions in passé or coupé positions with a short gesture leg "foot down" after each revolution. In addition, they were passively turned through 14 revolutions on a motor-driven rotating chair. Participants' centre-of-pressure (COP) displacement was measured on a force-plate before and after the rotations. Moreover, the dancers indicated their subjective feeling of dizziness on a scale from 0 to 20 directly after the rotations. Both the active and passive conditions were completed with and without the dancers spotting. As expected, dizziness was worse after rotations without the adoption of the spotting technique, both in active and passive rotations. However, the pre-post difference in COP area after active rotations was unaffected by spotting, whereas in the passive condition, spotting diminished this difference. Our results thus suggest that adopting the spotting technique is a useful tool for dizziness reduction in dancers who have to perform multiple rotations. Moreover, spotting appears most beneficial for postural stability when it involves less postural control challenges, such as when seated on a chair and occurs in situations with limited somatosensory feedback (e.g., from the cutaneous receptors in the feet). However, the unexpected finding that spotting did not help postural stability after active rotations needs to be investigated further in future studies, for example with a detailed analysis of whole-body kinematics and eye-tracking.

Camera-Monitor Systems as An Opportunity to Compensate for Perceptual Errors in Time-to-Contact Estimations.

For the safety of road traffic, it is crucial to accurately estimate the time it will take for a moving object to reach a specific location (time-to-contact estimation, TTC). Observers make more or less accurate TTC estimates of objects of average size that are moving at constant speeds. However, they make perceptual errors when judging objects which accelerate or which are unusually large or small. In the former case, for instance, when asked to extrapolate the motion of an accelerating object, observers tend to assume that the object continues to move with the speed it had before it went out of sight. In the latter case, the TTC of large objects is underestimated, whereas the TTC of small objects is overestimated, as if physical size is confounded with retinal size (the size-arrival effect). In normal viewing, these perceptual errors cannot be helped, but camera-monitor systems offer the unique opportunity to exploit the size-arrival effect to cancel out errors induced by the failure to respond to acceleration. To explore whether such error cancellation can work in principle, we conducted two experiments using a prediction-motion paradigm in which the size of the approaching vehicle was manipulated. The results demonstrate that altering the vehicle's size had the expected influence on the TTC estimation. This finding has practical implications for the implementation of camera-monitor systems.

Trial-by-trial feedback fails to improve the consideration of acceleration in visual time-to-collision estimation.

When judging the time-to-collision (TTC) of visually presented accelerating vehicles, untrained observers do not adequately account for acceleration (second-order information). Instead, their estimations only rely on vehicle distance and velocity (first-order information). As a result, they systemically overestimate the TTC for accelerating objects, which represents a potential risk for pedestrians in traffic situations because it might trigger unsafe road-crossing behavior. Can training help reduce these estimation errors? In this study, we tested whether training with trial-by-trial feedback about the signed deviation of the estimated from the actual TTC can improve TTC estimation accuracy for accelerating vehicles. Using a prediction-motion paradigm, we measured the estimated TTCs of twenty participants for constant-velocity and accelerated vehicle approaches, from a pedestrian's perspective in a VR traffic simulation. The experiment included three blocks, of which only the second block provided trial-by-trial feedback about the TTC estimation accuracy. Participants adjusted their estimations during and after the feedback, but they failed to differentiate between accelerated and constant-velocity approaches. Thus, the feedback did not help them account for acceleration. The results suggest that a safety training program based on trial-by-trial feedback is not a promising countermeasure against pedestrians' erroneous TTC estimation for accelerating objects.

Task-relevant social cues affect whole-body approach-avoidance behavior.

Positively evaluated stimuli facilitate approach and negatively evaluated stimuli prompt avoidance responses, as typically measured by reaction time differences when moving a joystick toward the own body or away from it. In this study, we explore whether a whole-body response (forward and backward leaning can serve as a better indicator of approach-avoidance behavior; AA). Thirty-two subjects were presented with pictures of males and females with angry or happy facial expressions. Subjects had to perform approach or avoidance responses by leaning forward or backward, either based on the facial expression of the stimulus or the gender of the stimulus. Leaning responses were sensitive to angry faces for explicit decision cues. Here, angry facial expressions facilitated backward leaning but not when responding to the gender of the stimulus. We compare this to the established manual measure of AA and discuss our results with regard to response coding.

Emotionally congruent music and text increase immersion and appraisal.

Numerous studies indicate that listening to music and reading are processes that interact in multiple ways. However, these interactions have rarely been explored with regard to the role of emotional mood. In this study, we first conducted two pilot experiments to assess the conveyed emotional mood of four classical music pieces and that of four narrative text excerpts. In the main experiment, participants were asked to read the texts while listening to the music and to rate their emotional state in terms of valence, arousal, and dominance. Subsequently, they rated text and music of the multisensory event in terms of the perceived mood, liking, immersion, and music-text fit. We found a mutual carry-over effect of happy and sad moods from music to text and vice versa. Against our expectations, this effect was not mediated by the valence, arousal, or dominance experienced by the subject. Moreover, we revealed a significant interaction between music mood and text mood. Texts were liked better, they were classified as of better quality, and participants felt more immersed in the text if text mood and music mood corresponded. The role of mood congruence when listening to music while reading should not be ignored and deserves further exploration.

A Case for Raising the Camera: A Driving Simulator Test of Camera-Monitor Systems.

OBJECTIVE: This experiment provides a first-of-its-kind driving-simulator study to investigate the feasibility of camera-monitor systems (CMS) with displaced side-mounted cameras in sedans. BACKGROUND: Among the increasing number of studies investigating the replacement of side-mounted rearview mirrors with CMS, the placement of side-mounted cameras has been largely neglected. Moreover, user preferences with respect to camera placement have not been validated in a driving simulator. Past research merely has shown that the vertical camera position can affect distance perception. METHOD: In a driving simulator experiment, we investigated the effects of rearward camera placement on driver acceptance and performance. Thirty-six participants performed multiple lane changes in a last safe-gap paradigm. The camera position, ego-velocity, and velocity of the approaching vehicle varied across the experiment. RESULTS: The results suggest a clear preference for a high rearward perspective, whereas participants disliked the lower viewpoint. However, these stark differences were only marginally mirrored in lane change performance. Average safety margins tended to decrease and their variation tended to increase for the low camera position. CONCLUSION: Even if the impact of the camera position on driving behavior seems to be small in sedans, driver expectations show clear-cut preferences. When designing CMS, this should be taken into account, as these preferences could promote the use of CMS and thus their positive impact on safety. APPLICATION: Designers should place side-mounted cameras as high as possible to increase acceptance of CMS. Low camera positions are not recommended, as they might decrease safety margins and are not appreciated by drivers.

How facial masks alter the interaction of gaze direction, head orientation, and emotion recognition.

The COVID-19 pandemic has altered the way we interact with each other: mandatory mask-wearing obscures facial information that is crucial for emotion recognition. Whereas the influence of wearing a mask on emotion recognition has been repeatedly investigated, little is known about the impact on interaction effects among emotional signals and other social signals. Therefore, the current study sought to explore how gaze direction, head orientation, and emotional expression interact with respect to emotion perception, and how these interactions are altered by wearing a face mask. In two online experiments, we presented face stimuli from the Radboud Faces Database displaying different facial expressions (anger, fear, happiness, neutral, and sadness), gaze directions (-13°, 0°, and 13°), and head orientations (-45°, 0°, and 45°) - either without (Experiment 1) or with mask (Experiment 2). Participants categorized the displayed emotional expressions. Not surprisingly, masks impaired emotion recognition. Surprisingly, without the mask, emotion recognition was unaffected by averted head orientations and only slightly affected by gaze direction. The mask strongly interfered with this ability. The mask increased the influence of head orientation and gaze direction, in particular for the emotions that were poorly recognized with mask. The results suggest that in case of uncertainty due to ambiguity or absence of signals, we seem to unconsciously factor in extraneous information.

Emotions are associated with the genesis of visually induced motion sickness in virtual reality.

Visually induced motion sickness (VIMS) is a well-known side effect of virtual reality (VR) immersion, with symptoms including nausea, disorientation, and oculomotor discomfort. Previous studies have shown that pleasant music, odor, and taste can mitigate VIMS symptomatology, but the mechanism by which this occurs remains unclear. We predicted that positive emotions influence the VIMS-reducing effects. To investigate this, we conducted an experimental study with 68 subjects divided into two groups. The groups were exposed to either positive or neutral emotions before and during the VIMS-provoking stimulus. Otherwise, they performed exactly the same task of estimating the time-to-contact while confronted with a VIMS-provoking moving starfield stimulation. Emotions were induced by means of pre-tested videos and with International Affective Picture System (IAPS) images embedded in the starfield simulation. We monitored emotion induction before, during, and after the simulation, using the Self-Assessment Manikin (SAM) valence and arousal scales. VIMS was assessed before and after exposure using the Simulator Sickness Questionnaire (SSQ) and during simulation using the Fast Motion Sickness Scale (FMS) and FMS-D for dizziness symptoms. VIMS symptomatology did not differ between groups, but valence and arousal were correlated with perceived VIMS symptoms. For instance, reported positive valence prior to VR exposure was found to be related to milder VIMS symptoms and, conversely, experienced symptoms during simulation were negatively related to subjects' valence. This study sheds light on the complex and potentially bidirectional relationship of VIMS and emotions and provides starting points for further research on the use of positive emotions to prevent VIMS.

Crossmodal Correspondence between Music and Ambient Color Is Mediated by Emotion.

The quality of a concert hall primarily depends on its acoustics. But does visual input also have an impact on musical enjoyment? Does the color of ambient lighting modulate the perceived music quality? And are certain colors perceived to fit better than others with a given music piece? To address these questions, we performed three within-subjects experiments. We carried out two pretests to select four music pieces differing in tonality and genre, and 14 lighting conditions of varying hue, brightness, and saturation. In the main experiment, we applied a fully crossed repeated-measures design. Under each of the four lighting conditions, participants rated the musical variables 'Harmonic', 'Powerful', 'Gloomy', 'Lively' and overall liking of the music pieces, as well as the perceived fit of music and lighting. Subsequently, participants evaluated music and lighting separately by rating the same variables as before, as well as their emotional impact (valence, arousal, dominance). We found that music and lighting being similarly rated in terms of valence and arousal in the unimodal conditions were judged to match better when presented together. Accordingly, tonal (atonal) music was rated to fit better with weakly saturated (highly saturated) colors. Moreover, some characteristics of the lighting were carried over to music. That is, just as red lighting was rated as more powerful than green and blue lighting, music was evaluated to be more powerful under red compared to green and blue lighting. We conclude that listening to music is a multisensory process enriched by impressions from the visual domain.

Vestibular Stimulation Causes Contraction of Subjective Time.

As the cerebellum is involved in vestibular and time-keeping processes, we asked if the latter are related. We conducted three experiments to investigate the effects of vestibular stimulation on temporal processing of supra-second durations. In Experiment 1, subjects had to perform temporal productions of 10- and 15-s intervals either standing on both feet or while being engaged in the difficult balancing task of standing on one foot with their eyes closed (or open for control purposes). In Experiment 2, participants were required to produce intervals of 5, 10, 15, and 20 s while standing on both feet with their eyes open or closed, which constituted an easier balancing task. In Experiment 3, we removed the active balancing; temporal productions of the same four durations had to be performed with the eyes open or closed during the passive vestibular stimulation induced by the oscillatory movements of a swing. Participants produced longer intervals when their eyes were closed, but active balancing was not the culprit. On the contrary, temporal over-production was particularly pronounced during the passive vestibular stimulation brought about by the swing movements. Taken together, the experiments demonstrate that the contraction of the subjective time during balancing tasks with closed eyes is most likely of vestibular origin.

Chewing gum reduces visually induced motion sickness.

Visually induced motion sickness (VIMS) is a common side-effect of exposure to virtual reality (VR). Its unpleasant symptoms may limit the acceptance of VR technologies for training or clinical purposes. Mechanical stimulation of the mastoid and diverting attention to pleasant stimuli-like odors or music have been found to ameliorate VIMS. Chewing gum combines both in an easy-to-administer fashion and should thus be an effective countermeasure against VIMS. Our study investigated whether gustatory-motor stimulation by chewing gum leads to a reduction of VIMS symptoms. 77 subjects were assigned to three experimental groups (control, peppermint gum, and ginger gum) and completed a 15-min virtual helicopter flight, using a VR head-mounted display. Before and after VR exposure, we assessed VIMS with the Simulator Sickness Questionnaire (SSQ), and during the virtual flight once every minute with the Fast Motion Sickness Scale (FMS). Chewing gum (peppermint gum: M = 2.44, SD = 2.67; ginger gum: M = 2.57, SD = 3.30) reduced the peak FMS scores by 2.05 (SE = 0.76) points as compared with the control group (M = 4.56, SD = 3.52), p < 0.01, d = 0.65. Additionally, taste ratings correlated slightly negatively with both the SSQ and the peak FMS scores, suggesting that pleasant taste of the chewing gum is associated with less VIMS. Thus, chewing gum may be useful as an affordable, accepted, and easy-to-access way to mitigate VIMS in numerous applications like education or training. Possible mechanisms behind the effect are discussed.

Wider is better but sharper is not: optimizing the image of camera-monitor systems.

The replacement of rear-view mirrors with camera-monitor systems introduces new opportunities for design, such as altering the image quality and the rearward field-of-view. We investigated how the image quality and field-of-view might affect the distance and time-to-contact estimation of other vehicles. Eighty-six subjects estimated either their egocentric distance to a stationary vehicle (Experiment I) or the time-to-contact to an approaching vehicle (Experiment II). Throughout the experiments, the pixel density and either the field-of-view or the viewing condition varied. A larger field-of-view increased distance estimation accuracy and confidence. Reduced pixel density led to larger estimates. In contrast, reduced pixel density and simulated dirt shortened time-to-contact estimates. This is compatible with a safety strategy applied under conditions of impaired vision. Moreover, a limited benefit was observed for higher pixel densities. Therefore, camera-monitor systems with large field-of-view and a pixel density of around 300 ppi could ensure accurate TTC and distance estimation. Practitioner summary: A camera's field-of-view and image quality are important parameters for camera-monitor systems. In two experiments, we investigated the effects of these two parameters on rearward distance and time-to-contact estimation. Whereas a larger field-of-view improved distance estimation accuracy, increasing the pixel density had a limited effect in the estimation of time-to-contact.

Inverting the Wollaston Illusion: Gaze Direction Attracts Perceived Head Orientation.

In the early 19th century, William H. Wollaston impressed the Royal Society of London with engravings of portraits. He manipulated facial features, such as the nose, and thereby dramatically changed the perceived gaze direction, although the eye region with iris and eye socket had remained unaltered. This Wollaston illusion can be thought of as head orientation attracting perceived gaze direction when the eye region is unchanged. In naturalistic viewing, the eye region changes with head orientation and typically produces a repulsion effect. Here we explore if there is a flip side to the illusion. Does the gaze direction also alter the perceived direction of the head? We used copies of the original drawings and a computer-rendered avatar as stimuli. Gaze direction does indeed alter perceived head orientation. Perceived head orientation is biased toward the direction of gaze.

Estimating time-to-contact when vision is impaired.

Often, we have to rely on limited information when judging time-to-contact (TTC), as for example, when driving in foul weather, or in situations where we would need reading glasses but do not have them handy. However, most existing studies on the ability to judge TTC have worked with optimal visual stimuli. In a prediction motion task, we explored to what extent TTC estimation is affected by visual stimulus degradation. A simple computer-simulated object approached the observer at constant speed either with clear or impaired vision. It was occluded after 1 or 1.5 s. The observers extrapolated the object's motion and pressed a button when they thought the object would have collided with them. We found that dioptric blur and simulated snowfall shortened TTC-estimates. Contrast reduction produced by a virtual semi-transparent mask lengthened TTC estimates, which could be the result of distance overestimation or speed underestimation induced by the lower contrast or the increased luminance of the mask. We additionally explored the potential influence of arousal and valence, although they played a minor role for basic TTC estimation. Our findings suggest that vision impairments have adverse effects on TTC estimation, depending on the specific type of degradation and the changes of the visual environmental cues which they cause.

Visual and postural eye-height information is flexibly coupled in the perception of virtual environments.

We conducted two experiments to investigate how observers integrate postural and visual eye-height information when estimating the layout of interior space. In Experiment 1, we varied postural and visual eye-height information independently of each other in a virtual-reality setup. Observers estimated the width, depth, and height of simulated rooms. All dimensions were perceived as larger when the virtual visual eye-height corresponded to sitting on the floor as compared with standing upright. In contrast, the estimates remained widely unaffected by the observer's physical posture (likewise sitting vs. standing). In Experiment 2, we studied effects of the viewing condition (real vs. virtual rooms) and (in case of the virtual rooms) adaptation to congruence versus incongruence of visual and postural information. Both media yielded comparable results, which indicates that eye-height information is processed similarly in virtual and genuine reality. In addition, observers adapted to the (in)congruence of visual and postural cues. When we presented trials with congruent information first, both visual and postural cues had an effect on the estimates. However, when information was initially incongruent, observers mostly relied on visual cues, presumably relative to an internalized standard, and disregarded postural cues. Taken together, our results show that the integration of visual and postural eye-height information is situation-dependent. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The Ups and Downs of Camera-Monitor Systems: The Effect of Camera Position on Rearward Distance Perception.

OBJECTIVE: This study investigates the effects of different positions of side-mounted rear-view cameras on distance estimation of drivers. BACKGROUND: Camera-monitor systems bring advantages as compared to conventional rear-view mirrors, such as improved aerodynamics and enlarged field-of-view. Applied research has mainly focused on the comparison between cameras and mirrors or on positioning of in-vehicle monitors. However, the positioning of the exterior camera awaits investigation given that the perspective of the observer at does affect depth perception at large. METHOD: In two experiments, a total of 50 students estimated metric distances to static vehicles presented in realistic or 3D-rendered pictures. The pictures depicted the rearward scene of a car following the driver as viewed through a camera at varying vertical and horizontal positions. The following vehicle's size and environmental information varied among conditions and experiments. RESULTS: Lower camera positions led to distance overestimation and higher positions to underestimation. The effect increased as the distance to the following vehicle decreased. Moreover, larger vehicles led to stronger distance underestimation, especially in low camera positions. Interestingly, the main effect of camera position disappeared when the ego-vehicles' back was visible. CONCLUSION: Different rearward viewpoints affect distance estimation of drivers, especially in close distances. However, a visible reference of one's own vehicle seems to mostly compensate this effect. APPLICATION: In general, the rear-view camera should be mounted rather higher and to the front of the vehicle. Also, the vehicle's back should always be visible. Low camera positions are not recommended.

Interpersonal Distance in the SARS-CoV-2 Crisis.

BACKGROUND: Mandatory rules for social distancing to curb the SARS-CoV-2 pandemic require individuals to maintain a critical interpersonal distance above 1.5 m. However, this contradicts our natural preference, which is closer to 1 m for non-intimate encounters, for example, when asking a stranger for directions. OBJECTIVE: This review addresses how humans typically regulate interpersonal distances, in order to highlight the challenges of enforcing atypically large interpersonal distances. METHOD: To understand the challenges posed by social distancing requirements, we integrate relevant contributions from visual perception, social perception, and human factors. RESULTS: To date, research on preferred interpersonal distances suggests that social distancing could induce discomfort, heighten arousal, and decrease social signaling in the short term. While the protracted effects of social distancing are unclear, we propose hypotheses on the mid- to long-term consequences of violating preferred norms of interpersonal distances. CONCLUSION: We suggest that enforcing a physical distance of 1.5-2 m presents a serious challenge to behavioral norms. APPLICATION: We address how notifications, architectural design, and visualizations could be effectively applied to promote interpersonal distance requirements.

Sexual attraction modulates interpersonal distance and approach-avoidance movements towards virtual agents in males.

How does sexual attraction alter social interaction behavior? We examined the influence of sexual orientation on locomotor approach-avoidance behavior and interpersonal distance. We immersed androphilic and gynophilic male subjects into a virtual environment and presented various male and female virtual persons. In the first experiment, subjects took a step forward (approach) or backward (avoidance) in response to the sex of the virtual person. We measured reaction time, peak velocity, and step size, and obtained ratings of sexual attractiveness in every trial. In the second experiment, subjects had to approach the virtual person as if they were to engage in a social interaction. Here, we analyzed interpersonal distance and peak velocity of the approaches. Our results suggest that sexual attraction facilitates the approach response and reduces the preferred interpersonal distance. We discuss our findings in terms of proxemics, current findings in sex research, and the applicability of our novel task in other fields of psychological research.

Quantifying the Wollaston Illusion.

In the early 19th century, William H. Wollaston impressed the Royal Society of London with engravings of portraits. He manipulated facial features, such as the nose, and thereby dramatically changed the perceived gaze direction, although the eye region with iris and eye socket had remained unaltered. This Wollaston illusion has been replicated numerous times but never with the original stimuli. We took the eyes (pupil and iris) from Wollaston's most prominent engraving and measured their perceived gaze direction in an analog fashion. We then systematically added facial features (eye socket, eyebrows, nose, skull, and hair). These features had the power to divert perceived gaze direction by up to 20°, which confirms Wollaston's phenomenal observation. The effect can be thought of as an attractor effect, that is, cues that indicate a slight change in head orientation have the power to divert perceived gaze direction.

Acceptance of truck platooning by professional drivers on German highways. A mixed methods approach.

Truck platoon driving is a current branch of automated driving, which has the potential to radically change the work routine of professional drivers. In a platoon system, one truck (semi-)automatically follows a lead truck with a reduced distance, which produces significant savings in fuel and enables better traffic flow. In a current application of truck platoon driving, the following vehicle operates at level-2 automation. Thus, the driver of the following truck merely has to supervise the semi-automated system, which takes over steering and speed control when engaged. Level-2 truck platoon driving had not been tested with professional drivers in real traffic before. We hypothesized that user acceptance would improve after the experience of platoon driving. Quantitative questionnaires and qualitative interviews were conducted with 10 drivers before and after an extensive Autobahn experience. The results show a clear increase of acceptance after the experience. Platoon driving was evaluated to be more useful, easier to use, and safer after the experience. Besides perceived driving safety, the prestige of truck platooning, the perceived usefulness of the system, and general technology affinity co-determined user acceptance.