Eye movements influence estimation of time-to-contact in prediction motion

Predictive posture stabilization before contact with moving objects: equivalence of smooth pursuit tracking and peripheral vision

Postural stabilization is essential to effectively interact with our environment. Humans preemptively adjust their posture to counteract impending disturbances, such as those encountered during interactions with moving objects, a phenomenon known as anticipatory postural adjustments (APAs). APAs are thought to be influenced by predictive models that incorporate object motion via retinal motion and extraretinal signals. Building on our previous work that examined APAs in relation to the perceived momentum of moving objects, here we explored the impact of object motion within different visual field sectors on the human capacity to anticipate motion and prepare APAs for contact between virtual moving objects and the limb. Participants interacted with objects moving toward them under different gaze conditions. In one condition, participants fixated on either a central point (central fixation) or left-right of the moving object (peripheral fixation), whereas in another, they followed the moving object with smooth pursuit eye movements (SPEMs). We found that APAs had the smallest magnitude in the central fixation condition and that no notable differences in APAs were apparent between the SPEM and peripheral fixation conditions. This suggests that the visual system can accurately perceive motion of objects in peripheral vision for posture stabilization. Using Bayesian model averaging, we also evaluated the contribution of different gaze variables, such as eye velocity and gain (ratio of eye and object velocity) and showed that both eye velocity and gain signals were significant predictors of APAs. Taken together, our study underscores the roles of oculomotor signals in the modulation of APAs.NEW & NOTEWORTHY We show that the human visuomotor system can detect motion in peripheral vision and make anticipatory adjustments to posture before contact with moving objects, just as effectively as when the eye movement system tracks those objects with smooth pursuit eye movements. These findings pave the way for research into how age-induced changes in spatial vision, eye movements, and motion perception could affect the control of limb movements and postural stability during motion-mediated interactions with objects.

Prediction of time to contact under perceptual and contextual uncertainties

Accurately estimating time to contact (TTC) is crucial for successful interactions with moving objects, yet it is challenging under conditions of sensory and contextual uncertainty, such as occlusion. In this study, participants engaged in a prediction motion task, monitoring a target that moved rightward and an occluder. The participants' task was to press a key when they predicted the target would be aligned with the occluder's right edge. We manipulated sensory uncertainty by varying the visible and occluded periods of the target, thereby modulating the time available to integrate sensory information and the duration over which motion must be extrapolated. Additionally, contextual uncertainty was manipulated by having a predictable and unpredictable condition, meaning the occluder either reliably indicated where the moving target would disappear or provided no such indication. Results showed differences in accuracy between the predictable and unpredictable occluder conditions, with different eye movement patterns in each case. Importantly, the ratio of the time the target was visible, which allows for the integration of sensory information, to the occlusion time, which determines perceptual uncertainty, was a key factor in determining performance. This ratio is central to our proposed model, which provides a robust framework for understanding and predicting human performance in dynamic environments with varying degrees of uncertainty.

The role of arousal in the estimation of time-to-collision of threatening stimuli

The accurate estimation of time-to-collision (TTC) is essential for the survival of organisms. Previous studies have revealed that the emotional properties of approaching stimuli can influence the estimation of TTC, indicating that approaching threatening stimuli are perceived to collide with the observers earlier than they actually do, and earlier than non-threatening stimuli. However, not only are threatening stimuli more negative in valence, but they also have higher arousal compared to non-threatening stimuli. Up to now, the effect of arousal on TTC estimation remains unclear. In addition, inconsistent findings may result from the different experimental settings employed in previous studies. To investigate whether the underestimation of TTC is attributed to threat or high arousal, three experiments with the same settings were conducted. In Experiment 1, the underestimation of TTC estimation of threatening stimuli was replicated when arousal was not controlled, in comparison to non-threatening stimuli. In Experiments 2 and 3, the underestimation effect of threatening stimuli disappeared when compared to positive stimuli with similar arousal. These findings suggest that being threatening alone is not sufficient to explain the underestimation effect, and arousal also plays a significant role in the TTC estimation of approaching stimuli. Further studies are required to validate the effect of arousal on TTC estimation, as no difference was observed in Experiment 3 between the estimated TTC of high and low arousal stimuli.

An update on tests used for intraoperative monitoring of cognition during awake craniotomy

PURPOSE

Mapping higher-order cognitive functions during awake brain surgery is important for cognitive preservation which is related to postoperative quality of life. A systematic review from 2018 about neuropsychological tests used during awake craniotomy made clear that until 2017 language was most often monitored and that the other cognitive domains were underexposed (Ruis, J Clin Exp Neuropsychol 40(10):1081-1104, 218). The field of awake craniotomy and cognitive monitoring is however developing rapidly. The aim of the current review is therefore, to investigate whether there is a change in the field towards incorporation of new tests and more complete mapping of (higher-order) cognitive functions.

METHODS

We replicated the systematic search of the study from 2018 in PubMed and Embase from February 2017 to November 2023, yielding 5130 potentially relevant articles. We used the artificial machine learning tool ASReview for screening and included 272 papers that gave a detailed description of the neuropsychological tests used during awake craniotomy.

RESULTS

Comparable to the previous study of 2018, the majority of studies (90.4%) reported tests for assessing language functions (Ruis, J Clin Exp Neuropsychol 40(10):1081-1104, 218). Nevertheless, an increasing number of studies now also describe tests for monitoring visuospatial functions, social cognition, and executive functions.

CONCLUSIONS

Language remains the most extensively tested cognitive domain. However, a broader range of tests are now implemented during awake craniotomy and there are (new developed) tests which received more attention. The rapid development in the field is reflected in the included studies in this review. Nevertheless, for some cognitive domains (e.g., executive functions and memory), there is still a need for developing tests that can be used during awake surgery.

Atypical Time to Contact Estimation in Young Adults with Autism Spectrum Disorder

Individuals with Autism Spectrum Disorder (ASD) present atypical sensory processing in the perception of moving stimuli and biological motion. The present study aims to explore the performance of young adults with ASD in a time to contact (TTC) estimation task involving social and non-social stimuli. TTC estimation involves extrapolating the trajectory of a moving target concealed by an occluder, based on the visible portion of its path, to predict the target's arrival time at a specific position. Sixteen participants with a diagnosis of level-1 ASD (M = 19.2 years, SE = 0.54 years; 3 F, 13 M) and sixteen participants with TD (M = 22.3 years, SE = 0.44 years; 3 F, 13 M) took part in the study and underwent a TTC estimation task. The task presented two object types (a car and a point-light walker), different object speeds, occluder lengths, motion directions and motion congruency. For the car object, a larger overestimation of TTC emerged for ASDs than for TDs, whereas no difference between ASDs and TDs emerged for the point-light walker. ASDs exhibited a larger TTC overestimation for the car object than for the point-light walker, whereas no difference between object types emerged for TDs. Our results indicated an atypical TTC estimation process in young adults with ASD. Given its importance in daily life, future studies should further explore this skill. Significant effects that emerged from the analysis are discussed.

A binary acceleration signal reduces overestimation in pedestrians' visual time-to-collision estimation for accelerating vehicles

When a pedestrian intends to cross the street, it is essential for safe mobility to correctly estimate the arrival time (time-to-collision, TTC) of an approaching vehicle. However, visual perception of acceleration is rather imprecise. Previous studies consistently showed that humans (mostly) disregard acceleration, but judge the TTC for an object as if it were traveling at constant speed (first-order estimation), which is associated with overestimated TTCs for positively accelerating objects. In a traffic context, such TTC overestimation could motivate pedestrians to cross in front of an approaching vehicle, although the time remaining is not sufficiently long. Can a simple acceleration signal help improve visual TTC estimation for accelerating objects? The present study investigated whether a signal that only indicates whether a vehicle is accelerating or not can remove the first-order pattern of overestimated TTCs. In a virtual reality simulation, 26 participants estimated the TTC of vehicles that approached with constant velocity or accelerated, from the perspective of a pedestrian at the curb. In half of the experimental blocks, a light band on the windshield illuminated whenever the vehicle accelerated but remained deactivated when the vehicle travelled at a constant speed. In the other blocks, the light band never illuminated, regardless of whether or not the vehicle accelerated. Participants were informed about the light band function in each block. Without acceleration signal, the estimated TTCs for the accelerating vehicles were consistent with an erroneous first-order approximation. In blocks with acceleration signal, participants substantially changed their estimation strategy, so that TTC overestimations for accelerating vehicles were reduced. Our data suggest that a binary acceleration signal helps pedestrians to effectively reduce the TTC overestimation for accelerating vehicles and could therefore increase pedestrian safety.

Human estimates of descending objects' motion are more accurate than those of ascending objects regardless of gravity information

Humans can accurately estimate and track object motion, even if it accelerates. Research shows that humans exhibit superior estimation and tracking performance for descending (falling) than ascending (rising) objects. Previous studies presented ascending and descending targets along the gravitational and body axes in an upright posture. Thus, it is unclear whether humans rely on congruent information between the direction of the target motion and gravity or the direction of the target motion and longitudinal body axes. Two experiments were conducted to explore these possibilities. In Experiment 1, participants estimated the arrival time at a goal for both upward and downward motion of targets along the longitudinal body axis in the upright (both axes of target motion and gravity congruent) and supine (both axes incongruent) postures. In Experiment 2, smooth pursuit eye movements were assessed while tracking both targets in the same postures. Arrival time estimation and smooth pursuit eye movement performance were consistently more accurate for downward target motion than for upward motion, irrespective of posture. These findings suggest that the visual experience of seeing an object moving along an observer's leg side in everyday life may influence the ability to accurately estimate and track the descending object's motion.

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.

The effect of impaired velocity signals on goal-directed eye and hand movements

Information about position and velocity is essential to predict where moving targets will be in the future, and to accurately move towards them. But how are the two signals combined over time to complete goal-directed movements? We show that when velocity information is impaired due to using second-order motion stimuli, saccades directed towards moving targets land at positions where targets were ~ 100 ms before saccade initiation, but hand movements are accurate. Importantly, the longer latencies of hand movements allow for additional time to process the sensory information available. When increasing the period of time one sees the moving target before making the saccade, saccades become accurate. In line with that, hand movements with short latencies show higher curvature, indicating corrections based on an update of incoming sensory information. These results suggest that movements are controlled by an independent and evolving combination of sensory information about the target's position and velocity.

Neurobehavioral measures of coincidence anticipation timing

Coincidence anticipation (CA) refers to the ability to coordinate responses to the arrival of a moving object. This study investigates the neurobehavioral processes that underlie CA through the measurement of electroencephalography (EEG) recorded during a CA task on a 17-foot plastic rail with evenly spaced LED lights. Participants responded at the anticipated moment a sequence of successively lit LEDs coincided with a stationary target. Healthy young adult participants (Mage = 21) performed six blocks with movement at 20, 30, or 40 mph and the direction either inbound or outbound relative to the participant. Behavioral results demonstrated a main effect of speed and an interaction between speed and direction, with outbound motion producing early responses and inbound motion producing delayed responses that increased at greater speeds. EEG demonstrated characteristic P1, N2, and P3-like visual evoked potentials (VEPs). VEP amplitudes revealed a significant direction by channel interaction for the P1, indicative of more medial responses for inbound motion. Significant laterality differences were present in the N2, whereas the P3 component produced significant main effects and interactions of speed and direction. This novel combination of three-dimensional CA with EEG demonstrates systematic brain responses that are tuned for motion speed and sensitive to different egocentric motion patterns thereby shedding new light on the mechanism of human visual-motor control.

Age-related decline of online visuomotor adaptation: a combined effect of deteriorations of motor anticipation and execution

The literature has established that the capability of visuomotor adaptation decreases with aging. However, the underlying mechanisms of this decline are yet to be fully understood. The current study addressed this issue by examining how aging affected visuomotor adaptation in a continuous manual tracking task with delayed visual feedback. To distinguish separate contributions of the declined capability of motor anticipation and deterioration of motor execution to this age-related decline, we recorded and analyzed participants' manual tracking performances and their eye movements during tracking. Twenty-nine older people and twenty-three young adults (control group) participated in this experiment. The results showed that the age-related decline of visuomotor adaptation was strongly linked to degraded performance in predictive pursuit eye movement, indicating that declined capability motor anticipation with aging had critical influences on the age-related decline of visuomotor adaptation. Additionally, deterioration of motor execution, measured by random error after controlling for the lag between target and cursor, was found to have an independent contribution to the decline of visuomotor adaptation. Taking these findings together, we see a picture that the age-related decline of visuomotor adaptation is a joint effect of the declined capability of motor anticipation and the deterioration of motor execution with aging.

Motion duration is overestimated behind an occluder in action and perception tasks

Motion estimation behind an occluder is a common task in situations like crossing the street or passing another car. People tend to overestimate the duration of an object's motion when it gets occluded for subsecond motion durations. Here, we explored (a) whether this bias depended on the type of interceptive action: discrete keypress versus continuous reach and (b) whether it was present in a perception task without an interceptive action. We used a prediction-motion task and presented a bar moving across the screen with a constant velocity that later became occluded. In the action task, participants stopped the occluded bar when they thought the bar reached the goal position via keypress or reach. They were more likely to stop the bar after it passed the goal position regardless of the action type, suggesting that the duration of occluded motion was overestimated (or its speed was underestimated). In the perception task, where participants judged whether a tone was presented before or after the bar reached the goal position, a similar bias was observed. In both tasks, the bias was near constant across motion durations and directions and grew over trials. We speculate that this robust bias may be due to a temporal illusion, Bayesian slow-motion prior, or the processing of the visible-occluded boundary crossing. Understanding its exact mechanism, the conditions on which it depends, and the relative roles of speed and time perception requires further research.

Eye movements during optic flow perception

Optic flow is an important visual cue for human perception and locomotion and naturally triggers eye movements. Here we investigate whether the perception of optic flow direction is limited or enhanced by eye movements. In Exp. 1, 23 human observers localized the focus of expansion (FOE) of an optic flow pattern; in Exp. 2, 18 observers had to detect brief visual changes at the FOE. Both tasks were completed during free viewing and fixation conditions while eye movements were recorded. Task difficulty was varied by manipulating the coherence of radial motion from the FOE (4 %-90 %). During free viewing, observers tracked the optic flow pattern with a combination of saccades and smooth eye movements. During fixation, observers nevertheless made small-scale eye movements. Despite differences in spatial scale, eye movements during free viewing and fixation were similarly directed toward the FOE (saccades) and away from the FOE (smooth tracking). Whereas FOE localization sensitivity was not affected by eye movement instructions (Exp. 1), observers' sensitivity to detect brief changes at the FOE was 27 % higher (p <.001) during free-viewing compared to fixation (Exp. 2). This performance benefit was linked to reduced saccade endpoint errors, indicating the direct beneficial impact of foveating eye movements on performance in a fine-grain perceptual task, but not during coarse perceptual localization.

Auditory affective content facilitates time-to-contact estimation of visual affective targets

Reacting to a moving object requires an ability to estimate when a moving object reaches its destination, also referred to as the time-to-contact (TTC) estimation. Although the TTC estimation of threatening visually moving objects is known to be underestimated, the effect of the affective content of auditory information on visual TTC estimation remains unclear. We manipulated the velocity and presentation time to investigate the TTC of a threat or non-threat target with the addition of auditory information. In the task, a visual or an audiovisual target moved from right to left and disappeared behind an occluder. Participants' task was to estimate the TTC of the target, they needed to press a button when they thought that the target contacted a destination behind the occluder. Behaviorally, the additional auditory affective content facilitated TTC estimation; velocity was a more critical factor than presentation time in determining the audiovisual threat facilitation effect. Overall, the results indicate that exposure to auditory affective content can influence TTC estimation and that the effect of velocity on TTC estimation will provide more information than presentation time.

Are predictive saccades linked to the processing of peripheral information?

High-level athletes can predict the actions of an opposing player. Interestingly, such predictions are also reflected by the athlete's gaze behavior. In cricket, for example, players first pursue the ball with their eyes before they very often initiate two predictive saccades: one to the predicted ball-bounce point and a second to the predicted ball-bat-contact point. That means, they move their eyes ahead of the ball and "wait" for the ball at the new fixation location, potentially using their peripheral vision to update information about the ball's trajectory. In this study, we investigated whether predictive saccades are linked to the processing of information in peripheral vision and if predictive saccades are superior to continuously following the ball with foveal vision using smooth-pursuit eye-movements (SPEMs). In the first two experiments, we evoked the typical eye-movements observed in cricket and showed that the information gathered during SPEMs is sufficient to predict when the moving object will hit the target location and that (additional) peripheral monitoring of the object does not help to improve performance. In a third experiment, we show that it could actually be beneficial to use SPEMs rather than predictive saccades to improve performance. Thus, predictive saccades ahead of a target are unlikely to be performed to enhance the peripheral monitoring of target.

The Effect of Target Velocity on the Fast Corrective Response during Reaching Movement

Online motor control is often required to correct errors in rapid adjustments during reaching movements. It has been established that the initial arm trajectory during reaching is corrected by a target displacement. Since this corrective response occurs without perception of target perturbation, this is regarded as an automatic response. However, an object rarely "jumps" in daily life, rather it often "moves" as a chronological change of the position that causes visual motion. Therefore, the purpose of this study was to investigate whether the implicit visuomotor response is induced by target motion stimuli and to clarify the effects of target motion velocity on initial arm trajectory. Participants were asked to move a cursor from a start circle to a visual target. The target moved either leftward or rightward when the cursor passed 20 mm from the start circle. Four target velocities (10, 20, 30, 40 deg/s) were randomly presented. Our results showed that the initial velocity (first 50 ms) of the fast corrective response increased with the target velocity. Therefore, it is indicated that the fast corrective response is induced by the target motion stimulus with a short latency and its amplitude is dependent on the target velocity.

Changes in visual speed perception induced by anticipatory smooth eye movements

Expectations about forthcoming visual motion shaped by observers' experiences are known to induce anticipatory smooth eye movements (ASEM) and changes in visual perception. Previous studies have demonstrated discrete effects of expectations on the control of ASEM and perception. However, the tasks designed in these studies were not able to segregate the effects of expectations and execution of ASEM itself on perception. In the current study, we attempted to directly examine the effect of ASEM itself on visual speed perception using a two-alternative forced-choice task (2AFC task), in which observers were asked to track a pair of sequentially presented visual motion stimuli with their eyes and to judge whether the second stimulus (test stimulus) was faster or slower than the first (reference stimulus). Our results showed that observers' visual speed perception, quantified by a psychometric function, shifted according to ASEM velocity. This was the case, even though there was no difference in the steady-state eye velocity. Further analyses revealed that the observers' perceptual decisions could be explained by a difference in the magnitude of retinal slip velocity in the initial phase of ocular tracking when the reference and test stimuli were presented, rather than in the steady-state phase. Our results provide psychophysical evidence of the importance of initial ocular tracking in visual speed perception and the strong impact of ASEM.

Coincidence Anticipation Timing Responses with Head Tracking and Eye Tracking

BACKGROUND: Head tracking movements are common in interceptive tasks. The benefits of these movements are unclear. The purpose of this study was to compare coincidence anticipation timing (CAT) responses for a simulated approaching object when the eyes were used in tracking the object and when the head was used in tracking the object.METHODS: A total of 29 subjects participated. A Bassin Anticipation Timer consisting of a track of sequentially illuminated lights was used to simulate an approaching object at velocities of 223 cm · s^-1 to 894 cm · s^-1. Each velocity was used 10 times under 2 conditions. In one condition, subjects were told to turn the eyes with the stimulus. In the other condition, subjects viewed the stimulus through apertures and were told to turn the head with the stimulus. Subjects pushed a button to coincide with illumination of the final light on the track.RESULTS: Signed CAT errors, unsigned CAT errors, and variable CAT errors were compared between the head movement (HM) and eye movement (EM) conditions. No significant differences were noted for the signed errors (mean signed error at 894 cm · s^-1; 10.3 ± 75.4 ms (HM), -16.1 ± 51.0 ms (EM). However, the unsigned and variable errors were significantly larger at some stimulus velocities in the head movement condition [mean unsigned error at 894 cm · s^-1: 82.6.0 ± 45.9 ms (HM), 59.0 ± 22.4 ms (EM); mean variable error at 894 cm · s^-1; 78.0 ± 37.8 ms (HM), 49.2 ± 17.1ms (EM)].DISCUSSION: Head movement did not result in improved CAT performance compared to eye movements. Further work will be required to determine whether these results are generalizable to situations where head tracking is required but apertures are not worn.Ross E, Kinney M, Fogt N. Coincidence anticipation timing responses with head tracking and eye tracking. Aerosp Med Hum Perform. 2022; 93(2):79-88.

Global-local consistency benefits memory-guided tracking of a moving target

INTRODUCTION

Previous findings have demonstrated that several Gestalt principles do facilitate VSTM performance in change detection tasks. However, few studies have investigated the role of and time-course of global-local consistency in motion perception.

METHODS

Participants were required to track a moving target surrounded by three different backgrounds: blank, inconsistent, or consistent. Global-local objects were be bound to move together (covariation). During the PMT, participants had to follow the moving target with their eyes and react as fast as possible when the target had just vanished behind the obstruction or would arrive at a predetermined point of interception. Variable error (VE) and constant error (CE) of estimated time-to-contact (TTC) and gain of smooth pursuit eye movements were calculated in various conditions and analyzed qualitatively.

RESULTS

Experiment 1 established the basic finding that VSTM performance could benefit from global-local consistency. Experiment 2 extended this finding by eye-tracking device. Both in visible phase and in occluded phase, CEs were smaller for the target in a consistent background than for the target in an inconsistent background and for the target in a blank background, with both differences significant (ps < .05). However, the difference in VE among three conditions was not significant. At early stage (100-250 ms), later stage (2750-3000 ms), and termination stage (5750-6000 ms) of smooth pursuit, the velocity gains were higher in the trials with consistent backgrounds than in the trials with inconsistent backgrounds and blank backgrounds (ps < .001). With the exception of 100-250 ms phase, the means did not differ between the inconsistent background and the blank background trials (ps > .1).

CONCLUSIONS

Global-local consistency could be activated within the first few hundred milliseconds to prioritize the deployment of attention and eye movement to component target. Meanwhile, it also removes ambiguity from motion tracking and TTC estimation under some unpredictable conditions, leading to the consistency advantage during smooth-pursuit termination phase. Global-local consistency may act as an important information source to TTC estimation and oculomotor response in PMT.

The role of eye movements in perceiving vehicle speed and time-to-arrival at the roadside

To avoid collisions, pedestrians depend on their ability to perceive and interpret the visual motion of other road users. Eye movements influence motion perception, yet pedestrians' gaze behavior has been little investigated. In the present study, we ask whether observers sample visual information differently when making two types of judgements based on the same virtual road-crossing scenario and to which extent spontaneous gaze behavior affects those judgements. Participants performed in succession a speed and a time-to-arrival two-interval discrimination task on the same simple traffic scenario-a car approaching at a constant speed (varying from 10 to 90 km/h) on a single-lane road. On average, observers were able to discriminate vehicle speeds of around 18 km/h and times-to-arrival of 0.7 s. In both tasks, observers placed their gaze closely towards the center of the vehicle's front plane while pursuing the vehicle. Other areas of the visual scene were sampled infrequently. No differences were found in the average gaze behavior between the two tasks and a pattern classifier (Support Vector Machine), trained on trial-level gaze patterns, failed to reliably classify the task from the spontaneous eye movements it elicited. Saccadic gaze behavior could predict time-to-arrival discrimination performance, demonstrating the relevance of gaze behavior for perceptual sensitivity in road-crossing.

Disrupting Short-Term Memory Maintenance in Premotor Cortex Affects Serial Dependence in Visuomotor Integration

Human behavior is biased by past experience. For example, when intercepting a moving target, the speed of previous targets will bias responses in future trials. Neural mechanisms underlying this so-called serial dependence are still under debate. Here, we tested the hypothesis that the previous trial leaves a neural trace in brain regions associated with encoding task-relevant information in visual and/or motor regions. We reasoned that injecting noise by means of transcranial magnetic stimulation (TMS) over premotor and visual areas would degrade such memory traces and hence reduce serial dependence. To test this hypothesis, we applied bursts of TMS pulses to right visual motion processing region hV5/MT+ and to left dorsal premotor cortex (PMd) during intertrial intervals of a coincident timing task performed by twenty healthy human participants (15 female). Without TMS, participants presented a bias toward the speed of the previous trial when intercepting moving targets. TMS over PMd decreased serial dependence in comparison to the control Vertex stimulation, whereas TMS applied over hV5/MT+ did not. In addition, TMS seems to have specifically affected the memory trace that leads to serial dependence, as we found no evidence that participants' behavior worsened after applying TMS. These results provide causal evidence that an implicit short-term memory mechanism in premotor cortex keeps information from one trial to the next, and that this information is blended with current trial information so that it biases behavior in a visuomotor integration task with moving objects.SIGNIFICANCE STATEMENT Human perception and action are biased by the recent past. The origin of such serial bias is still not fully understood, but a few components seem to be fundamental for its emergence: the brain needs to keep previous trial information in short-term memory and blend it with incoming information. Here, we present evidence that a premotor area has a potential role in storing previous trial information in short-term memory in a visuomotor task and that this information is responsible for biasing ongoing behavior. These results corroborate the perspective that areas associated with processing information of a stimulus or task also participate in maintaining that information in short-term memory even when this information is no longer relevant for current behavior.

The influence of time structure on prediction motion in visual and auditory modalities

Usually people can estimate the correct position of a moving object even when it temporarily moves behind an occlusion. Studies have been performed on this type of occluded motion with prediction motion (PM) tasks in the laboratory. Previous publications have emphasized that people could use mental imagery or apply an oculomotor system to estimate the arrival of a moving stimulus at the target place. Nevertheless, these two ways cannot account for the performance difference under a different set of conditions. Our study tested the role of time structure in a time-to-collision (TTC) task using visual and auditory modalities. In the visual condition, the moving red bar travelled from left to right and was invisible during the entire course but flashed at the initial and the occluded points. The auditory condition and visual condition were alike, except that the flashes in the visual condition were changed to clicks at the initial and the occluded points. The results illustrated that participants' performance was better in the equal time structure condition. The comparison between the two sense modalities demonstrated a similar tendency, which suggested there could be common cognitive processes between visual and auditory modalities when participants took advantage of temporal cues to judge TTC.

The effect of explicit cues on smooth pursuit termination

Predictive deceleration of eye motion during smooth pursuit is induced by explicit cues indicating the timing of the visual target offset. The first aim of this study (experiment 1) was to determine whether the timing of the onset of cue-based predictive pursuit termination depends on spatial or temporal information using three target velocities. The second aim (experiment 2) was to examine whether an unexpected offset of the target affects the pursuit termination. We conducted a pursuit termination task where participants tracked a moving target and then stopped tracking after the target disappeared. The results of experiment 1 showed that the onset times of predictive eye deceleration were consistent regardless of target velocity, indicating that its timing is controlled by the temporal estimation, rather than the spatial distance between the target and cue positions. In experiment 2, we compared pursuit termination between the following two conditions. One condition did not present any cues (unknown condition), whereas a second condition included a same cue as experiment 1 but the target disappeared 500 ms before the timing indicated by the cue unpredictably (unexpected condition). As a result, the unexpected condition showed significant delays in the onset of eye deceleration, but no difference in the total time for completion of pursuit termination. Therefore, our findings suggest that the cue-based pursuit termination is controlled by the predictive pursuit system, and an unexpected offset of the target yields delays in the onset of eye deceleration, while does not affect the duration of pursuit termination.

Resolving visual motion through perceptual gaps

Perceptual gaps can be caused by objects in the foreground temporarily occluding objects in the background or by eyeblinks, which briefly but frequently interrupt visual information. Resolving visual motion across perceptual gaps is particularly challenging, as object position changes during the gap. We examine how visual motion is maintained and updated through externally driven (occlusion) and internally driven (eyeblinks) perceptual gaps. Focusing on both phenomenology and potential mechanisms such as suppression, extrapolation, and integration, we present a framework for how perceptual gaps are resolved over space and time. We finish by highlighting critical questions and directions for future work.

The influence of auditory rhythms on the speed of inferred motion

The present research explored the influence of isochronous auditory rhythms on the timing of movement-related prediction in two experiments. In both experiments, participants observed a moving disc that was visible for a predetermined period before disappearing behind a small, medium, or large occluded area for the remainder of its movement. In Experiment 1, the disc was visible for 1 s. During this period, participants were exposed to either a fast or slow auditory rhythm, or they heard nothing. They were instructed to press a key to indicate when they believed the moving disc had reached a specified location on the other side of the occluded area. The procedure measured the (signed) error in participants' estimate of the time it would take for a moving object to contact a stationary one. The principal results of Experiment 1 were main effects of the rate of the auditory rhythm and of the size of the occlusion on participants' judgments. In Experiment 2, the period of visibility was varied with size of the occlusion area to keep the total movement time constant for all three levels of occlusion. The results replicated the main effect of rhythm found in Experiment 1 and showed a small, significant interaction, but indicated no main effect of occlusion size. Overall, the results indicate that exposure to fast isochronous auditory rhythms during an interval of inferred motion can influence the imagined rate of such motion and suggest a possible role of an internal rhythmicity in the maintenance of temporally accurate dynamic mental representations.

Review: Head and Eye Movements and Gaze Tracking in Baseball Batting

SIGNIFICANCE

After a 30-year gap, several studies on head and eye movements and gaze tracking in baseball batting have been performed in the last decade. These baseball studies may lead to training protocols for batting. Here we review these studies and compare the tracking behaviors with those in other sports.Baseball batters are often instructed to "keep your eye on the ball." Until recently, the evidence regarding whether batters follow this instruction and if there are benefits to following this instruction was limited. Baseball batting studies demonstrate that batters tend to move the head more than the eyes in the direction of the ball at least until a saccade occurs. Foveal gaze tracking is often maintained on the ball through the early portion of the pitch, so it can be said that baseball batters do keep the eyes on the ball. While batters place gaze at or near the point of bat-ball contact, the way this is accomplished varies. In some studies, foveal gaze tracking continues late in the pitch trajectory, whereas in other studies, anticipatory saccades occur. The relative advantages of these discrepant gaze strategies on perceptual processing and motor planning speed and accuracy are discussed, and other variables that may influence anticipatory saccades including the predictability of the pitch and the level of batter expertise are described. Further studies involving larger groups with different levels of expertise under game conditions are required to determine which gaze tracking strategies are most beneficial for baseball batting.

Effects of smooth pursuit and second-order stimuli on visual motion prediction

The purpose of this study was to determine whether smooth pursuit eye movements affect visual motion prediction using a time‐to‐contact task where observers anticipate the exact instant that a partially occluded target would coincide with a stationary object. Moreover, we attempted to clarify the influence of second‐order motion on visual motion prediction during smooth pursuit. One target object moved to another stationary object (6 deg apart) at constant velocity of 3, 4, and 5 deg/s, and then the two objects disappeared 500 ms after the onset of target motion. The observers estimated the moment the moving object would overlap the stationary object and pressed a button. For the pursuit condition, both a Gaussian window and a random dots texture moved in the same direction at the same speed for the first‐order motion, whereas a Gaussian window moved over a static background composed of random dots texture for the second‐order motion. The results showed that the constant error of the time‐to‐contact shifted to a later response for the pursuit condition compared to the fixation condition, regardless of the object velocity. In addition, during smooth pursuit, the constant error for the second‐order motion shifted to an earlier response compared to the first‐order motion when the object velocity was 3 deg/s, whereas no significant difference was found at 4 and 5 deg/s. Therefore, our results suggest that visual motion prediction using a time‐to‐contact task is affected by both eye movements and motion configuration such as second‐order motion.

The role of eye movements in manual interception: A mini-review

When we catch a moving object in mid-flight, our eyes and hands are directed toward the object. Yet, the functional role of eye movements in guiding interceptive hand movements is not yet well understood. This review synthesizes emergent views on the importance of eye movements during manual interception with an emphasis on laboratory studies published since 2015. We discuss the role of eye movements in forming visual predictions about a moving object, and for enhancing the accuracy of interceptive hand movements through feedforward (extraretinal) and feedback (retinal) signals. We conclude by proposing a framework that defines the role of human eye movements for manual interception accuracy as a function of visual certainty and object motion predictability.

Time-to-contact perception in the brain

Time-to-contact (TTC) perception refers to the ability of an observer to estimate the remaining time before an object reaches a point in the environment, and is of crucial importance in daily life. Noninvasive correlational approaches have identified several brain areas sensitive to TTC information. Here we report the results of two studies, including one during an awake brain surgery, that aimed to identify the specific areas causally engaged in the TTC estimation process. In Study 1, we tested 40 patients with brain tumor in a TTC estimation task. The results showed that four of the six patients with impaired performance had tumors in right upper parietal cortex, although this tumoral location represented only six over 40 patients. In Study 2, 15 patients underwent awake brain surgery electrostimulation mapping to examine the implication of various brain areas in the TTC estimation process. We acquired and normalized to MNI space the coordinates of the functional areas that influenced task performance. Our results seem to demonstrate that the early stage of the TTC estimation process involved specific cortical territories in the ventral region of the right intraparietal sulcus. Downstream processing of TTC could also involve the frontal eye field (middle frontal gyrus) related to ocular search. We also found that deactivating language areas in the left hemisphere interfered with the TTC estimation process. These findings demonstrate a fine grained, cortical representation of TTC processing close to the ventral right intraparietal sulcus and complement those described in other human studies.

Eye movements as a readout of sensorimotor decision processes

Real-world tasks, such as avoiding obstacles, require a sequence of interdependent choices to reach accurate motor actions. Yet, most studies on primate decision making involve simple one-step choices. Here we analyze motor actions to investigate how sensorimotor decisions develop over time. In a go/no-go interception task human observers (n = 42) judged whether a briefly presented moving target would pass (interceptive hand movement required) or miss (no hand movement required) a strike box while their eye and hand movements were recorded. Go/no-go decision formation had to occur within the first few hundred milliseconds to allow time-critical interception. We found that the earliest time point at which eye movements started to differentiate actions (go versus no-go) preceded hand movement onset. Moreover, eye movements were related to different stages of decision making. Whereas higher eye velocity during smooth pursuit initiation was related to more accurate interception decisions (whether or not to act), faster pursuit maintenance was associated with more accurate timing decisions (when to act). These results indicate that pursuit initiation and maintenance are continuously linked to ongoing sensorimotor decision formation.NEW & NOTEWORTHY Here we show that eye movements are a continuous indicator of decision processes underlying go/no-go actions. We link different stages of decision formation to distinct oculomotor events during open- and closed-loop smooth pursuit. Critically, the earliest time point at which eye movements differentiate actions preceded hand movement onset, suggesting shared sensorimotor processing for eye and hand movements. These results emphasize the potential of studying eye movements as a readout of cognitive processes.

The effect of symbolic meaning of speed on time to contact

The effects of moving task-irrelevant objects on time-to-contact (TTC) judgments are examined in six experiments. In particular, we investigated the effects of the symbolic meaning of speed on TTC by presenting images of objects recalling the symbolic meaning of high speed (motorbike, rocket, formula one, rabbit, cheetah and flying Superman) and low speed (bicycle, hot-air balloon, tank, turtle, elephant and static Superman). In all experiments, participants judged the TTC of these moving objects with a black line, indicating the end of the occlusion. Experiment 7 was conducted to disambiguate whether the effects on TTC, found in the previous experiments, were either a by-product of a speed illusion or they were rather elicited by the implicit timing task. In a two-interval forced choice task, participants were instructed to judge if "high-speed objects" moved actually faster than "slow-speed objects". The results revealed no consistent speed illusion. Taken together the results showed shorter TTC estimated with stimuli recalling the meaning of high compared to low speed, but only with the long occlusion duration (3.14 s). At shorter occlusion durations, the pattern was reversed (participant tend to have shorter TTC with stimuli recalling the meaning of low speed). We suggest that the symbolic meaning of speed works mainly at low speed and long TTC, because the semantic elaboration of the stimulus needs a deeper cognitive elaboration. On the other hand, at higher speeds, a small erroneous perceptual judgment affects the TTC, perhaps due to a speed expectancy violation of the expected "slow object".

Auditory pitch glides influence time-to-contact judgements of visual stimuli

A common experimental task used to study the accuracy of estimating when a moving object arrives at a designated location is the time-to-contact (TTC) task. The previous studies have shown evidence that sound motion cues influence TTC estimates of a visual moving object. However, the extent to which sound can influence TTC of visual targets still remains unclear. Some studies on the crossmodal correspondence between pitch and speed suggest that descending pitch sounds are associated with faster speeds compared to ascending pitch sounds due to an internal model of gravity. Other studies have shown an opposite pitch-speed mapping (i.e., ascending pitch associated with faster speeds) and no influence of gravity heuristics. Here, we explored whether auditory pitch glides, a continuous pure tone sound either ascending or descending in pitch, influence TTC estimates of a vertically moving visual target and if any observed effects are consistent with a gravity-centered or gravity-unrelated pitch-speed mapping. Subjects estimated when a disc moving either upward or downward at a constant speed reached a visual landmark after the disc disappeared behind an occluder under three conditions: with an accompanying ascending pitch glide, with a descending pitch glide, or with no sound. Overall, subjects underestimated TTC with ascending pitch glides and overestimated TTC with descending pitch glides, compared to the no-sound condition. These biases in TTC were consistent in both disc motion directions. These results suggest that subjects adopted a gravity-unrelated pitch-speed mapping where ascending pitch is associated with faster speeds and descending pitch associated with slower speeds.

Availability of attention affects time-to-contact estimation

To estimate the time-to-contact (TTC) of a moving object, numerous studies have focused on the type of information or gaze strategy used by the observer. However, it remains to be determined whether and how attention could affect TTC estimation. In particular, how does TTC estimation operate when less attention is available? To answer this question, we conducted two experiments in which the participants had to perform an absolute (Experiment 1) or relative (Experiment 2) prediction-motion task, either alone (i.e., in single-task condition) or along with a secondary, visual working-memory task (i.e., in dual-task condition). In both experiments, we found that TTC estimation was superior in dual-task condition relative to single-task condition. This finding suggests that the reduction of available attention actually improves TTC estimation. We discuss possible explanations as well as theoretical implications for this seemingly counter-intuitive finding. Further research is needed to investigate if (in)attention facilitates or only shifts TTC estimation.

The function and failure of sensory predictions

Humans and other primates are equipped with neural mechanisms that allow them to automatically make predictions about future events, facilitating processing of expected sensations and actions. Prediction-driven control and monitoring of perceptual and motor acts are vital to normal cognitive functioning. This review provides an overview of corollary discharge mechanisms involved in predictions across sensory modalities and discusses consequences of predictive coding for cognition and behavior. Converging evidence now links impairments in corollary discharge mechanisms to neuropsychiatric symptoms such as hallucinations and delusions. We review studies supporting a prediction-failure hypothesis of perceptual and cognitive disturbances. We also outline neural correlates underlying prediction function and failure, highlighting similarities across the visual, auditory, and somatosensory systems. In linking basic psychophysical and psychophysiological evidence of visual, auditory, and somatosensory prediction failures to neuropsychiatric symptoms, our review furthers our understanding of disease mechanisms.

Asymmetrical time-to-contact error with two moving objects persists across different vertical separations

When human observers estimate the time-to-contact (TTC) of more than one object there is an asymmetric pattern of error consistent with prioritizing the lead object at the expense of the trail object. Here, we examined TTC estimation in a prediction motion task where two objects moved along horizontal trajectories (5 or 7.5 °/s) that had different vertical separation, and thus placed specific demands on visuospatial attention. Results showed that participants were able to accurately judge arrival order, irrespective of vertical separation, in all but two conditions where the object trajectories crossed close to the arrival location. Constant error was significantly higher for the object that trailed, as opposed to led, by 250 or 500 ms. Asymmetry in constant error between the lead and trail object was not influenced by vertical separation, and was also evident across a range of arrival times. However, while the lag between the two consecutive TTC estimations was scaled to the actual difference in object arrival times, lag did increase with vertical separation. Taken together, our results confirm that TTC estimation of two moving objects in the prediction motion task suffers from an asymmetrical interference, which is likely related to factors that influence attentional allocation.

Eye-hand coordination during flexible manual interception of an abruptly appearing, moving target

As a vital skill in an evolving world, interception of moving objects relies on accurate prediction of target motion. In natural circumstances, active gaze shifts often accompany hand movements when exploring targets of interest, but how eye and hand movements are coordinated during manual interception and their dependence on visual prediction remain unclear. Here, we trained gaze-unrestrained monkeys to manually intercept targets appearing at random locations and circularly moving with random speeds. We found that well-trained animals were able to intercept the targets with adequate compensation for both sensory transmission and motor delays. Before interception, the animals' gaze followed the targets with adequate compensation for the sensory delay, but not for extra target displacement during the eye movements. Both hand and eye movements were modulated by target kinematics, and their reaction times were correlated. Moreover, retinal errors and reaching errors were correlated across different stages of reach execution. Our results reveal eye-hand coordination during manual interception, yet the eye and hand movements may show different levels of prediction based on the task context.

NEW & NOTEWORTHY Here we studied the eye-hand coordination of monkeys during flexible manual interception of a moving target. Eye movements were untrained and not explicitly associated with reward. We found that the initial saccades toward the moving target adequately compensated for sensory transmission delays, but not for extra target displacement, whereas the reaching arm movements fully compensated for sensorimotor delays, suggesting that the mode of eye-hand coordination strongly depends on behavioral context.

Discrimination of curvature from motion during smooth pursuit eye movements and fixation

Smooth pursuit and motion perception have mainly been investigated with stimuli moving along linear trajectories. Here we studied the quality of pursuit movements to curved motion trajectories in human observers and examined whether the pursuit responses would be sensitive enough to discriminate various degrees of curvature. In a two-interval forced-choice task subjects pursued a Gaussian blob moving along a curved trajectory and then indicated in which interval the curve was flatter. We also measured discrimination thresholds for the same curvatures during fixation. Motion curvature had some specific effects on smooth pursuit properties: trajectories with larger amounts of curvature elicited lower open-loop acceleration, lower pursuit gain, and larger catch-up saccades compared with less curved trajectories. Initially, target motion curvatures were underestimated; however, ∼300 ms after pursuit onset pursuit responses closely matched the actual curved trajectory. We calculated perceptual thresholds for curvature discrimination, which were on the order of 1.5 degrees of visual angle (°) for a 7.9° curvature standard. Oculometric sensitivity to curvature discrimination based on the whole pursuit trajectory was quite similar to perceptual performance. Oculometric thresholds based on smaller time windows were higher. Thus smooth pursuit can quite accurately follow moving targets with curved trajectories, but temporal integration over longer periods is necessary to reach perceptual thresholds for curvature discrimination.NEW & NOTEWORTHY Even though motion trajectories in the real world are frequently curved, most studies of smooth pursuit and motion perception have investigated linear motion. We show that pursuit initially underestimates the curvature of target motion and is able to reproduce the target curvature ∼300 ms after pursuit onset. Temporal integration of target motion over longer periods is necessary for pursuit to reach the level of precision found in perceptual discrimination of curvature.

Context effects on smooth pursuit and manual interception of a disappearing target

In our natural environment, we interact with moving objects that are surrounded by richly textured, dynamic visual contexts. Yet most laboratory studies on vision and movement show visual objects in front of uniform gray backgrounds. Context effects on eye movements have been widely studied, but it is less well known how visual contexts affect hand movements. Here we ask whether eye and hand movements integrate motion signals from target and context similarly or differently, and whether context effects on eye and hand change over time. We developed a track-intercept task requiring participants to track the initial launch of a moving object ("ball") with smooth pursuit eye movements. The ball disappeared after a brief presentation, and participants had to intercept it in a designated "hit zone." In two experiments (n = 18 human observers each), the ball was shown in front of a uniform or a textured background that either was stationary or moved along with the target. Eye and hand movement latencies and speeds were similarly affected by the visual context, but eye and hand interception (eye position at time of interception, and hand interception timing error) did not differ significantly between context conditions. Eye and hand interception timing errors were strongly correlated on a trial-by-trial basis across all context conditions, highlighting the close relation between these responses in manual interception tasks. Our results indicate that visual contexts similarly affect eye and hand movements but that these effects may be short-lasting, affecting movement trajectories more than movement end points.NEW & NOTEWORTHY In a novel track-intercept paradigm, human observers tracked a briefly shown object moving across a textured, dynamic context and intercepted it with their finger after it had disappeared. Context motion significantly affected eye and hand movement latency and speed, but not interception accuracy; eye and hand position at interception were correlated on a trial-by-trial basis. Visual context effects may be short-lasting, affecting movement trajectories more than movement end points.

Fast moving texture has opposite effects on the perceived speed of visible and occluded object trajectories

In a series of psychophysical experiments, we altered the perceived speed of a spot (target) using a grayscale texture moving in the same (iso-motion) or opposite (anti-motion) direction of the target. In Experiment 1, using a velocity discrimination task (2IFC), the target moved in front of the texture and was perceived faster with anti-motion than iso-motion texture. The integration and segregation of motion signals in high-level motion areas may have accounted for the illusion. In Experiment 2, by asking observers to estimate the time-to-contact (TTC) with a bar indicating the end of the invisible trajectory, we showed that this illusory visible speed, due to anti- (iso-) texture, reduced (increased) the subsequent estimated duration of occluded target trajectory. However, in Experiment 3, when the target disappeared behind the iso-motion texture, the TTC was estimated shorter than anti- and static textures. In Experiment 4, using an interruption paradigm, we found negative Point of Subjective Equalities (PSEs) with iso-motion but not static texture, suggesting that iso-motion led to overestimation of the hidden speed. However, sensitivity to target speed differences, as assessed by JNDs and d'values was not affected. Results of Experiments 3 and 4 indicate that only the iso-texture affected the estimated target speed, but with opposite polarity compared to visible motion, suggesting a different origin of speed bias. Because our results show that visuospatial tracking was facilitated by the fast iso-motion, we conclude that motion of the occluded target was tracked by shifting visuospatial attention.

EFFECTS OF SPATIAL AND TEMPORAL CONSTRAINTS ON INTERCEPTIVE AIMING TASK PERFORMANCE AND GAZE CONTROL

The perceptual process of obtaining and using visual information plays a critical role in determining the quality of interception performance. Eye-movement characteristics and their association with interception accuracy where the constraints imposed on the task influence the eye-movement control are not well understood. The effects of spatial and temporal constraints were examined and associated with target motion on interception accuracy and gaze control strategy. Twenty-four (M = 28 yr., SD = 10; 10 women) inexperienced dart throwers volunteered for the study. Eye movements were measured while the participants attempted to intercept a horizontally moving target with a thrown dart. A mixed design experiment was employed with a between- (specification of interception point) and a within- (target speed) subjects factor. As target speed increased, spatial errors about the moving target increased but temporal errors decreased. Specifying a fixed location for target interception resulted in greater errors about the moving target. The point of gaze tended to center on the interception point, and this became more evident with increased target speed and the specification of a fixed interception point. The experimental findings provide support for a visual search strategy that exhibits compliance with the constraints of the task.

Filling gaps in visual motion for target capture

A remarkable challenge our brain must face constantly when interacting with the environment is represented by ambiguous and, at times, even missing sensory information. This is particularly compelling for visual information, being the main sensory system we rely upon to gather cues about the external world. It is not uncommon, for example, that objects catching our attention may disappear temporarily from view, occluded by visual obstacles in the foreground. Nevertheless, we are often able to keep our gaze on them throughout the occlusion or even catch them on the fly in the face of the transient lack of visual motion information. This implies that the brain can fill the gaps of missing sensory information by extrapolating the object motion through the occlusion. In recent years, much experimental evidence has been accumulated that both perceptual and motor processes exploit visual motion extrapolation mechanisms. Moreover, neurophysiological and neuroimaging studies have identified brain regions potentially involved in the predictive representation of the occluded target motion. Within this framework, ocular pursuit and manual interceptive behavior have proven to be useful experimental models for investigating visual extrapolation mechanisms. Studies in these fields have pointed out that visual motion extrapolation processes depend on manifold information related to short-term memory representations of the target motion before the occlusion, as well as to longer term representations derived from previous experience with the environment. We will review recent oculomotor and manual interception literature to provide up-to-date views on the neurophysiological underpinnings of visual motion extrapolation.

Why do people appear not to extrapolate trajectories during multiple object tracking? A computational investigation

Intuitively, extrapolating object trajectories should make visual tracking more accurate. This has proven to be true in many contexts that involve tracking a single item. But surprisingly, when tracking multiple identical items in what is known as "multiple object tracking," observers often appear to ignore direction of motion, relying instead on basic spatial memory. We investigated potential reasons for this behavior through probabilistic models that were endowed with perceptual limitations in the range of typical human observers, including noisy spatial perception. When we compared a model that weights its extrapolations relative to other sources of information about object position, and one that does not extrapolate at all, we found no reliable difference in performance, belying the intuition that extrapolation always benefits tracking. In follow-up experiments we found this to be true for a variety of models that weight observations and predictions in different ways; in some cases we even observed worse performance for models that use extrapolations compared to a model that does not at all. Ultimately, the best performing models either did not extrapolate, or extrapolated very conservatively, relying heavily on observations. These results illustrate the difficulty and attendant hazards of using noisy inputs to extrapolate the trajectories of multiple objects simultaneously in situations with targets and featurally confusable nontargets.