Motion Judgments Research Articles

Can Stroboscopic Training Improve Time-to-Collision Judgments of Laterally Moving Objects?

We investigated whether effects of stroboscopic training on time-to-collision (TTC) judgments depend on the optical flow pattern. Prior research showed that TTC judgments of lateral motion reflected benefits of stroboscopic viewing (Ballester, Huertas, Uji, & Bennett, 2017; Smith & Mitroff, 2012), but TTC judgments of approach motion did not reflect such benefits (Braly & DeLucia, 2017). This discrepancy may be due to differences in the optical flow patterns between lateral and approach motion. In lateral motion, the optical flow pattern is linear; the change in the object’s optical position is the same throughout its trajectory. In approach motion, the optical flow pattern is non-linear; the change in the object’s optical size increases as it gets closer to the eye. It has been proposed that this difference in the optical flow pattern underlies the greater accuracy of TTC judgments that occur with lateral motion compared to approach motion (Schiff & Oldak, 1990). In the current study, we measured effects of stroboscopic viewing on TTC judgments of lateral motion using identical methods in our prior study of approach motion. Although prior research demonstrated potential benefits of stroboscopic viewing for judgments of lateral motion, the stimulus was visible when the response was made. Prior demonstrations that the object’s trajectory (and thus nature of the optic flow) affects TTC judgments were demonstrated with prediction-motion (PM) tasks in which the object disappeared before a response was made. The two types of tasks are putatively based on different visual information and cognitive processes (Tresilian, 1995). Thus, we used a PM task in the current study. Participants viewed computer simulations of an object that moved laterally toward a target and then disappeared. They pressed a mouse button at the exact time that they thought the object would hit the target. Mean constant error and variable error of TTC judgments were compared among intervention conditions of stroboscopic training (5 minutes in duration), continuous viewing (practice without feedback), and a control filler task. Performance was measured during four sessions—pre-test, intervention, immediately after intervention, and 10 minutes after intervention. When distance was far, participants in the stroboscopic intervention condition were, on average, less variable at the 10-minute posttest compared to the pretest. Although the difference was not statistically significant, it is noteworthy that performance did not significantly degrade over time as it did in the filler condition, and in our prior study of approach motion (Braly & DeLucia, 2017). Such results suggest that stroboscopic training can protect against performance degradation over time (due to fatigue, monotony, etc). A protective effect also was observed in the continuous vision condition (performance did not degrade over time); however, observations of the means suggest that performance would have degraded over time if longer training was completed. When TTC was 3.0 s, performance in the stroboscopic intervention was not more variable in the immediate posttest compared to the pretest and, more importantly, was less variable at the ten-minute posttest (although p = 0.0515). Our results show that under specific conditions (when TTC was 3.0 s; when distance was far) stroboscopic training can protect against performance degradation over time; that is, variable error did not increase. Such protective effects of stroboscopic training were not observed in our earlier study of approach motion (Braly & DeLucia, 2017). Neither study showed a significant effect of stroboscopic training on constant error. The implication is that the effects of stroboscopic training depend on the nature of the optical flow pattern. In future studies, it is important to systematically determine the conditions under which stroboscopic training can improve performance. Results will have important implications for traffic safety and for driver training programs.

Feature-continuous motion judgements: Assessing different random dot motion displays

Feature-continuous motion judgements: Assessing different random dot motion displays

Social Perception in Mesial Temporal Lobe Epilepsy: Interpreting Social Information From Moving Shapes and Biological Motion.

Dysfunction in the understanding of social signals has been reported in persons with epilepsy, which may partially explain lower levels of life satisfaction in this patient population. Extensive assessment is necessary, particularly when the mesial temporal lobe, responsible for emotion processing, is affected. The authors examined multiple levels of social perception in patients with mesial temporal lobe epilepsy (MTLE), including judgments of point-light motion displays of human communicative interactions (Communicative Interactions Database-5 Alternative Forced Choice format) and theory-of-mind processes evaluated using geometric shapes (Frith-Happé animations [FHA]). This case-control study included MTLE patients with anterior temporal lobectomies (ATL+) (N=19), MTLE patients without lobectomies (ATL-) (N=21), and healthy controls (HCs) (N=20). Both groups of MTLE patients were less efficient in recognizing goal-directed and mentalizing interactions of FHA compared with HC subjects. The ATL+ group attributed emotions to FHA less accurately than HC subjects. Both the ATL- and ATL+ groups classified individual point-light animations more often as communicative than the HC group. ATL+ patients were also less efficient in interpreting point-light animations in terms of individual actions than the HC group. The number of years of epilepsy duration was inversely correlated with recognition of FHA interactions. The mean number of seizures was inversely correlated with the interaction identification in point-light stimuli. Patients with MTLE, irrespective of surgical treatment, present impaired social perception in domains assessed with abstract moving shapes or nonabstract biological motion. This impairment may be the basis of problems faced by patients reporting difficulties in understanding the intentions and feelings of other individuals.

A method of detecting underwater weak target based on generalized Duffing oscillator

In the marine environment, when the line spectra of underwater target radiated signal are unknown or the continuous spectra are weak, it is extremely hard to accurately detect the underwater weak target. The line spectrum based method commonly requires spectrum information for detection, and the continuous spectrum based energy method is hard to achieve accurate detection in long distance. In this paper, an underwater radiated noise detection method based on generalized Duffing oscillator detection system is proposed. Firstly, a generalized Duffing oscillator detection system for non-periodic and non-stationary input signal is proposed through deducing the traditional Duffing oscillator detection system that is perturbed by periodic signal. And the proposed generalized Duffing oscillator detection system is able to detect the signals of targets without needing prior information. Secondly, when the target radiated signal (non-periodic and non-stationary signal) is input into the generalized Duffing oscillator, a special form of output phase space (a special state of motion) is discovered and the differences in output phase space among different input signals (periodic stationary signals, nonperiodic non-stationary signals and the target radiated signals) are analyzed. It is found that the special phase space has different form from the output phase spaces of other kinds of signals; accordingly the underwater targets can be detected through the representation of the difference between special phase space and ordinary phase space. Thirdly, a discrete distribution sequence calculation method based on phase space is proposed for the precise and efficient judgment of system motion. The proposed calculation method defines a similar-grid function, based on which, the distribution sequence calculation method of output phase space is deduced, and the distribution sequences of different kinds of output phase spaces are calculated. The method realizes an embedded expression of system output by using the statistical complexity, therefore achieving the embedded underwater target detection when the line spectra of underwater target radiated signal are unknown or the continuous spectra are weak. The analysis result indicates that the method is of low-computation. Finally, the experimental results in the sea are described and the lowest signalto-noise ratio (SNR) of the method is calculated to be -9.133 dB. Simulation and experimental results have shown that the proposed method can detect target successfully in a lower SNR than traditional detection method, and the real-time performance can meet the demand for underwater detection. The method in this paper provides new ideas and ways of thinking for underwater target detection, and has very important reference value for low SNR long-distance target detection under real condition.

Saccades create similar mislocalizations in visual and auditory space.

Orienting our eyes to a light, a sound, or a touch occurs effortlessly, despite the fact that sound and touch have to be converted from head- and body-based coordinates to eye-based coordinates to do so. We asked whether the oculomotor representation is also used for localization of sounds even when there is no saccade to the sound source. To address this, we examined whether saccades introduced similar errors of localization judgments for both visual and auditory stimuli. Sixteen subjects indicated the direction of a visual or auditory apparent motion seen or heard between two targets presented either during fixation or straddling a saccade. Compared with the fixation baseline, saccades introduced errors in direction judgments for both visual and auditory stimuli: in both cases, apparent motion judgments were biased in direction of the saccade. These saccade-induced effects across modalities give rise to the possibility of shared, cross-modal location coding for perception and action.

Nonvisual information contributes to flow parsing during walking

To perceive the movement of an independently moving object during self-motion, visual motion caused by object movement must be distinguished from effects of self-motion. This has been termed flow parsing. Flow parsing could be accomplished from optic flow alone. During walking, nonvisual information about self-motion could also potentially contribute. In this study, we measured the relative influence of visual and nonvisual information on perception of object motion and movement control during walking. In a virtual environment, observers walked toward a distant target along a textured ground plane. An independently moving dot appeared briefly during movement, 0.9 m above the ground, and observers judged whether the object was moving leftward or rightward. The horizontal velocity of the object was varied across trials and responses were used to compute a point-of-subjective-equality representing the object motion that is perceived to be stationary. To dissociate visual and nonvisual cues, we presented conditions where the direction of self-motion indicated by optic flow differed from the physical direction of walking by ±5°. In this situation, the relative motion of an object that is stationary with respect to optic flow would not correspond to a stationary object when compared to the physical direction of self-motion, and vice versa. The object motion that is perceived to be stationary can therefore be used to infer the relative influence of visual and nonvisual cues. We also analyzed walking trajectories to estimate the relative influence of visual and nonvisual cues on movement control. We found that nonvisual information strongly influenced both object motion judgments and walking trajectories, with less weighting for object motion (60% vs. 90%). We also found trial-to-trial correlations between biases in walking direction and judgments of object motion. The results suggest that an integrated perception of heading contributes to both movement control and flow parsing. Meeting abstract presented at VSS 2015

Gradual development of temporal attention in letter identification and motion judgment tasks

Gradual development of temporal attention in letter identification and motion judgment tasks

Unifying account of visual motion and position perception

Despite growing evidence for perceptual interactions between motion and position, no unifying framework exists to account for these two key features of our visual experience. We show that percepts of both object position and motion derive from a common object-tracking system--a system that optimally integrates sensory signals with a realistic model of motion dynamics, effectively inferring their generative causes. The object-tracking model provides an excellent fit to both position and motion judgments in simple stimuli. With no changes in model parameters, the same model also accounts for subjects' novel illusory percepts in more complex moving stimuli. The resulting framework is characterized by a strong bidirectional coupling between position and motion estimates and provides a rational, unifying account of a number of motion and position phenomena that are currently thought to arise from independent mechanisms. This includes motion-induced shifts in perceived position, perceptual slow-speed biases, slowing of motions shown in visual periphery, and the well-known curveball illusion. These results reveal that motion perception cannot be isolated from position signals. Even in the simplest displays with no changes in object position, our perception is driven by the output of an object-tracking system that rationally infers different generative causes of motion signals. Taken together, we show that object tracking plays a fundamental role in perception of visual motion and position.

Speed judgments of background motion and illusion of self-motion when viewing sinusoidal visual stimuli along fore-and-aft axis with different frequencies and velocities

Speed judgments of background motion and illusion of self-motion when viewing sinusoidal visual stimuli along fore-and-aft axis with different frequencies and velocities

Implied Dynamics Biases the Visual Perception of Velocity

We expand the anecdotic report by Johansson that back-and-forth linear harmonic motions appear uniform. Six experiments explore the role of shape and spatial orientation of the trajectory of a point-light target in the perceptual judgment of uniform motion. In Experiment 1, the target oscillated back-and-forth along a circular arc around an invisible pivot. The imaginary segment from the pivot to the midpoint of the trajectory could be oriented vertically downward (consistent with an upright pendulum), horizontally leftward, or vertically upward (upside-down). In Experiments 2 to 5, the target moved uni-directionally. The effect of suppressing the alternation of movement directions was tested with curvilinear (Experiment 2 and 3) or rectilinear (Experiment 4 and 5) paths. Experiment 6 replicated the upright condition of Experiment 1, but participants were asked to hold the gaze on a fixation point. When some features of the trajectory evoked the motion of either a simple pendulum or a mass-spring system, observers identified as uniform the kinematic profiles close to harmonic motion. The bias towards harmonic motion was most consistent in the upright orientation of Experiment 1 and 6. The bias disappeared when the stimuli were incompatible with both pendulum and mass-spring models (Experiments 3 to 5). The results are compatible with the hypothesis that the perception of dynamic stimuli is biased by the laws of motion obeyed by natural events, so that only natural motions appear uniform.

Joint tuning for direction of motion and binocular disparity in macaque MT is largely separable

Neurons in sensory cortical areas are tuned to multiple dimensions, or features, of their sensory space. Understanding how single neurons represent multiple features is of great interest for determining the informative dimensions of the neurons' response, the decoding algorithms appropriate for extracting this information from the neuronal population, and for determining where specific transformations occur along the visual hierarchy. Despite the established role of cortical area MT in judgments of motion and depth, it is not known how individual neurons jointly encode the two dimensions. We investigated the joint tuning of individual MT neurons for two visual features: direction of motion and binocular disparity, an important depth cue. We found that a separable, multiplicative combination of tuning for the two features can account for more than 90% of the variance in the joint tuning function for over 91% of MT neurons. These results suggest 1) that each feature can be read out independently from MT by simply averaging across the population without regard to the other feature and 2) that the inseparable representations seen in subsequent areas, such as MST, must be computed beyond MT. Intriguingly, we found that the remaining nonseparable component of the joint tuning function often manifested as small but systematic changes in the neurons' preferences for one feature as the other one was varied. We believe this reflects the local columnar organization of tuning for direction and binocular disparity in MT, indicating that joint tuning may provide a new tool with which to probe functional architecture.

Strategic Control Modulates Working Memory-Driven Attentional Capture

The current study used a naming task to investigate whether strategic control could modulate the process of attentional capture that is driven by working memory. The use of a naming task to engage working memory eliminates potential strategic perceptual resampling, which may have played a role in several previous studies. After naming a prime, participants performed a selection task in which they judged the direction of a moving target in each trial. Prime validity, which is the probability that the primes are identical to the selection targets, was manipulated across four experiments. The results showed that reaction times to the motion judgment were faster in the valid condition than in the invalid condition when the prime validity was 50% (Experiment 1A). These results occurred even in the presence of a highly informative spatial cue that predicted the target's location (Experiment 4). A larger capturing effect was observed when the validity was 70% (Experiments 2 and 3). When the prime validity was lower than the chance level (0% in Experiment 1B; 15% in Experiments 2 and 3), a validity effect was not observed. Thus, the results suggest that there is a strong tendency for working memory to capture attention by default when there is no reason to avoid the influence of primes. When there is a reason to avoid the influence, strategic control modulates the attentional capture that is driven by working memory.

Low-level motion analysis of color and luminance for perception of 2D and 3D motion

We investigated the low-level motion mechanisms for color and luminance and their integration process using 2D and 3D motion aftereffects (MAEs). The 2D and 3D MAEs obtained in equiluminant color gratings showed that the visual system has the low-level motion mechanism for color motion as well as for luminance motion. The 3D MAE is an MAE for motion in depth after monocular motion adaptation. Apparent 3D motion can be perceived after prolonged exposure of one eye to lateral motion because the difference in motion signal between the adapted and unadapted eyes generates interocular velocity differences (IOVDs). Since IOVDs cannot be analyzed by the high-level motion mechanism of feature tracking, we conclude that a low-level motion mechanism is responsible for the 3D MAE. Since we found different temporal frequency characteristics between the color and luminance stimuli, MAEs in the equiluminant color stimuli cannot be attributed to a residual luminance component in the color stimulus. Although a similar MAE was found with a luminance and a color test both for 2D and 3D motion judgments after adapting to either color or luminance motion, temporal frequency characteristics were different between the color and luminance adaptation. The visual system must have a low-level motion mechanism for color signals as for luminance ones. We also found that color and luminance motion signals are integrated monocularly before IOVD analysis, showing a cross adaptation effect between color and luminance stimuli. This was supported by an experiment with dichoptic presentations of color and luminance tests. In the experiment, color and luminance tests were presented in the different eyes dichoptically with four different combinations of test and adaptation: color or luminance test in the adapted eye after color or luminance adaptation. Findings of little or no influence of the adaptation/test combinations indicate the integration of color and luminance motion signals prior to the binocular IOVD process.

Before, during and after you disappear: aspects of timing and dynamic updating of the real-time action simulation of human motions

The detailed dynamics of action simulation was investigated using the occluder paradigm: a point light actor (PLA) was shown, then briefly occluded from view, during which period action simulation was generated. Following occlusion, the PLA reappeared, either a progression of the motion as it should be post-occlusion or temporally shifted earlier/later. Participants made judgements on whether the reappearing PLA was too early or too late to be a correct continuation (Experiments 1 and 3) or whether it was a veridical continuation or not (Experiment 2). Over three experiments we asked how action simulation is affected by motion information before, during and after occlusion. Reducing motion presented before occlusion retained the accuracy of action simulation judgements. Presenting 4 frames (67 ms) of PLA motion during the occluder duration dynamically updates or altogether regenerates the action simulation. Reducing the duration of the test motion after the occluder decreases judgement precision, which we interpret as a limitation in the process of postdictive motion judgments. Overall, this is further evidence that the action simulation process is remarkably adapted to making human motion predictions.

Gender and Hazard Perception Skills in Relation to Road Traffic Police Officers

Gender differences have been observed in driving styles and in the types of reported collisions that males and females are involved in. This study was conducted to examine gender differences in a hazard perception task independently of motion judgements. Participants were asked to rate a series of traffic still photos as to how hazardous they perceived the depicted situations to be. Several trained road traffic police officers were also asked to complete the task and act as an expert group with which the participants could be compared. The results showed that there was no gender difference, with males and females rating all scenes similarly, and that although the police officers demonstrated within-group consistency, there was no significant difference between their ratings and those of the civilians. It was concluded that hazard perception skills are not a major factor in the prevalence of collisions and that other factors such as overconfidence in one's own ability and consequent decision-making process...

Speed judgments of three-dimensional motion incorporate extraretinal information

When tracking an object moving in depth, the visual system should take changes of eye vergence into account to judge the object's 3D speed correctly. Previous work has shown that extraretinal information about changes in eye vergence is exploited when judging the sign of 3D motion. Here, we ask whether extraretinal signals also affect judgments of 3D speed. Observers judged the speed of a small target surrounded by a large background. To manipulate extraretinal information, we varied the vergence demand of the entire stimulus sinusoidally over time. At different phases of vergence pursuit, we changed the disparity of the target relative to the background, leading observers to perceive approaching target motion. We determined psychometric functions for the target's approach speed when the eyes were (1) converging, (2) diverging, (3) maximally converged (near), and (4) maximally diverged (far). The target's motion was reported as faster during convergence and slower during divergence but perceived speed was little affected at near or far vergence positions. Thus, 3D speed judgments are affected by extraretinal signals about changes in eye rotation but appear unaffected by the absolute orientation of the eyes. We develop a model that accounts for observers' judgments by taking a weighted average of the retinal and extraretinal signals to target motion.

Laryngeal and respiratory patterns in patients with paradoxical vocal fold motion

The purposes of this study were to determine the differences in spirometric measures obtained from patients with endoscopically-documented paradoxical vocal fold motion (PVFM) and to compare them to a group of normal subjects without endoscopically-documented paradoxical vocal fold motion during non-provocative breathing and following speech. Thirty eight subjects with documented paradoxical vocal fold motion using transnasal flexible laryngoscopy (TFL) and no history of asthma and 21 normal subjects with documented normal breathing patterns and normal findings on endoscopy underwent flow-volume loop studies. Endoscopic judgments of vocal fold motion from three breathing conditions were made by two observers. The results of the endoscopic judgments indicate that paradoxical motion occurs whether breathing through the nose or mouth in the PVFM subjects, mainly after speaking and inhalation. In addition, the spirometry results indicated that the inspiratory measure of FIVC%, FVC% and FIV(0.5)/FIVC were significantly lower in the PVFM group compared to the normal subjects. The data supports the hypothesis that in patients with PVFM, inspiratory spirometric values play a role in identifying patients with PVFM. The finding of vocal fold closure following a speech utterance in the majority of the PVFM subjects but not in the normal control group warrants further investigation.

Better performance with two eyes than with one in stereo-blind subjects’ judgments of motion in depth

Visual tasks that involve judging distance or depth obviously benefit from considering retinal disparities and ocular convergence, but various simple visual thresholds are also lower when looking with two eyes. This is also true for stereo-blind subjects. One benefit of using two eyes is that looking with two eyes provides two chances of making the critical distinction. From the literature it would appear that using two eyes might only be an advantage for low contrast stimuli and simple tasks. We here demonstrate that stereo-blind subjects can benefit from using two eyes when making judgments about clearly visible complex stimuli. The task was to judge the direction of rotation of a simulated transparent cylinder. Stereo-blind subjects performed better when looking with two eyes than when looking with their preferred eye. It did not matter for their performance whether the images in their two eyes were correlated or not. Various control experiments ascertained that they judged the direction of rotation from the images in each eye separately and then combined these judgments, rather than relying on differences between the images in the two eyes. These findings raise doubts about the validity of using monocular vision as a control for quantitative studies of the use of binocular disparity.

Action and attentional load can influence aperture effects on motion perception

When a moving featureless contour is viewed through a stationary circular aperture that occludes the contour's endpoints and the contour moves in a direction non-parallel to its orientation, observers report the contour's direction of motion as perpendicular to the contour's orientation regardless of its actual direction. In typical studies of this aperture effect on motion perception, observers made perceptual judgments of the line's motion. The aperture effect was not measured when observers actively controlled the line's motion. In addition, effects of attentional load on the aperture effect were not measured. Here, we demonstrated that attentional load influenced the aperture effect. Active control reduced the aperture effect, but did not eliminate it. Results have theoretical implications for motion perception and practical implications for the design of technologies that limit an observer's field-of-view such as surgical cameras.

Remapping motion across modalities: tactile rotations influence visual motion judgments

Multisensory interactions between haptics and vision remain poorly understood. Previous studies have shown that shapes, such as letters of the alphabet, when drawn on the skin, are differently perceived dependent upon which body part is stimulated and on how the stimulated body part, such as the hand, is positioned. Another line of research within this area has investigated multisensory interactions. Tactile perceptions, for example, have the potential to disambiguate visually perceived information. While the former studies focused on explicit reports about tactile perception, the latter studies relied on fully aligned multisensory stimulus dimensions. In this study, we investigated to what extent rotating tactile stimulations on the hand affect directional visual motion judgments implicitly and without any spatial stimulus alignment. We show that directional tactile cues and ambiguous visual motion cues are integrated, thus biasing the judgment of visually perceived motion. We further show that the direction of the tactile influence depends on the position and orientation of the stimulated part of the hand relative to a head-centered frame of reference. Finally, we also show that the time course of the cue integration is very versatile. Overall, the results imply immediate directional cue integration within a head-centered frame of reference.