Localization of moving sound

The final position of a moving sound source usually appears to be displaced in the direction of motion. We tested the hypothesis that this phenomenon, termed auditory representational momentum, is already emerging during, not merely after, the period of motion. For this purpose, we investigated the localization of a moving sound at different points in time. In a dark anechoic environment, an acoustic target moved along the frontal horizontal plane. In the initial, middle, or final phase of the motion trajectory, subjects received a tactile stimulus and determined the current position of the moving target at the moment of the stimulus by performing either relative-judgment or pointing tasks. Generally, in the initial phase of the auditory motion, the position was perceived to be displaced in the direction of motion, but this forward displacement disappeared in the further course of the motion. When the motion stimulus had ceased, however, its final position was again shifted in the direction of motion. The latter result suggests that representational momentum in spatial hearing is a phenomenon specific to the final point of motion. Mental extrapolation of past trajectory information is discussed as a potential source of this perceptual displacement.     

Localization of moving sound

The final position of a moving sound source usually appears to be displaced in the direction of motion. We tested the hypothesis that this phenomenon, termed auditory representational momentum, is already emerging during, not merely after, the period of motion. For this purpose, we investigated the localization of a moving sound at different points in time. In a dark anechoic environment, an acoustic target moved along the frontal horizontal plane. In the initial, middle, or final phase of the motion trajectory, subjects received a tactile stimulus and determined the current position of the moving target at the moment of the stimulus by performing either relative-judgment or pointing tasks. Generally, in the initial phase of the auditory motion, the position was perceived to be displaced in the direction of motion, but this forward displacement disappeared in the further course of the motion. When the motion stimulus had ceased, however, its final position was again shifted in the direction of motion. The latter result suggests that representational momentum in spatial hearing is a phenomenon specific to the final point of motion. Mental extrapolation of past trajectory information is discussed as a potential source of this perceptual displacement.     

Cast shadow can modulate the judged final position of a moving target

Observers tend to localize the final position of a suddenly vanished moving target farther along in the direction of the target motion (representational momentum). We report here that such localization errors are mediated by perceived motion rather than by retinal motion. By manipulating the cast shadow of a moving target, we induced illusory motion to a target stimulus while keeping the retinal motion constant. Participants indicated the vanishing point of the target by directing a mouse cursor. The resulting magnitude of localization errors was modulated on the basis of the induced direction of the target. Such systematic localization biases were not obtained in a control condition in which the motion paths of the ball and shadow were switched. Our results suggest that cues to object motion trajectory, such as cast shadows, are used for the localization task, supporting a view that a predictive mechanism is responsible for the production of localization errors.     

A matter of design: No representational momentum without predictability

When observers are asked to localize the final position of a moving target, a forward shift of the judged final position is observed. So far, the forward shift has been attributed to the influence of mental continuation of the final target position (representational momentum). However, studies investigating forward displacement have used highly predictable target motion. The direction of target motion and the final target position were often varied between subjects. Thus, observers may have expected the target to travel in a particular direction or vanish at a particular location before a given trial started. In this study, direction of motion and final position were treated as fixed or random factors. The forward shift and the reversal of the shift with time (memory averaging) were absent when both factors were randomized. Thus, the forward shift with implied motion is restricted to repeatedly observed motion sequences that allow for pre-trial motion prediction.     

Does representational momentum reflect a distortion of the length or the endpoint of a trajectory?

Observers viewed a moving target, and after the target vanished, indicated either the initial position or the final position of the target. In Experiment 1, an auditory tone cued observers to indicate either the initial position or the final position; in Experiment 2, different groups of observers indicated the initial position or the final position. Judgments of the initial position were displaced backward in the direction opposite to motion, and judgments of the final position were displaced forward in the direction of motion. The data suggest that the remembered trajectory is longer than the actual trajectory, and the displacement pattern is not consistent with the hypothesis that representational momentum results from a distortion of memory for the location of a trajectory.     

Attention maintains mental extrapolation of target position: irrelevant distractors eliminate forward displacement after implied motion

Observers' judgments of the final position of a moving target are typically shifted in the direction of implied motion ("representational momentum"). The role of attention is unclear: visual attention may be necessary to maintain or halt target displacement. When attention was captured by irrelevant distractors presented during the retention interval, forward displacement after implied target motion disappeared, suggesting that attention may be necessary to maintain mental extrapolation of target motion. In a further corroborative experiment, the deployment of attention was measured after a sequence of implied motion, and faster responses were observed to stimuli appearing in the direction of motion. Thus, attention may guide the mental extrapolation of target motion. Additionally, eye movements were measured during stimulus presentation and retention interval. The results showed that forward displacement with implied motion does not depend on eye movements. Differences between implied and smooth motion are discussed with respect to recent neurophysiological findings.     

Centripetal force draws the eyes,not memory of the target,toward the center

Many observers believe that a target will continue on a curved trajectory after exiting a spiral tube. Similarly, when observers were asked to localize the final position of a target moving on a circular orbit, displacement of the judged position in the direction of forward motion ("representational momentum") and toward the center of the orbit was observed (cf. T. L. Hubbard, 1996). The present study shows that memory displacement of targets on a circular orbit is affected by eye movements. Forward displacement was larger with ocular pursuit of the target, whereas inward displacement was larger with motionless eyes. The results challenge an account attributing forward and inward displacement to mental analogues of momentum and centripetal force, respectively.     

Representational Momentum Beyond Internalized Physics

Abstract— Prediction of future motion is necessary in order to successfully deal with moving objects. Implicit measures have been used to evaluate the sources of information used in this task. For instance, observers may be asked to localize the final position of a moving target. Judgments have been found to be displaced in the direction of motion (forward displacement), suggesting that observers have internalized a mental analogue of physical momentum. However, more recent studies have shown that forward displacement may not be caused by cognitive mechanisms alone. Rather, predictive mechanisms at the perceptual and motor levels may contribute to the forward error. Supporting the notion that mechanisms of anticipation may be embodied, the forward error was found to depend on the execution of eye and pointing movements. Also, forward displacement depended on the motion type that was presented (smooth vs. jerky or implied), which suggests that attention moves to the next expected target position to facilitate responses to this position.     

In space, the past can be recast but not the present

We address the relationship between perception and spatial, working memory. Specifically, we argue that perceptual experience following the creation of a representation of target location affects it in a systematic way. We designed a motor task in which observers had to point to the initial or final position of a horizontally drifting target embedded in a vertically drifting background. The target was perceived as having an illusory motion component in a direction opposite that of the inducer dots [Duncker, 1938, Source Book of Gestalt Psychology (London: Kegan Paul, Trench, Trubner and Co)]. For both positions, there was an identical time delay before the observer could respond. Nonetheless, estimates of the initial target position were significantly biased by the illusion in a direction opposite the perceived target motion, and both bias and variability were significantly greater than those of the target's final position. In prior studies on positional accuracy with induced displacement, a delay before a pointing response led to an unbiased position estimate obtained without delay to become biased, leading investigators to argue for a long-lasting, inaccurate cognitive system that overrules an accurate, nonetheless transient, motor one (Bridgeman et al, 1997, Perceptual Psychology 59 456-469). Since the same motor task with identical delay on either position yielded different outcomes, a hypothesis based on distinct motor and cognitive representations of visual space is untenable here. Instead, we argue that an online representation of the target's original position is updated in an ongoing fashion in order to reconcile the perceived illusion with the veridically perceived present (current target location).     

Asynchronous perception of motion and luminance change

Observers were asked to indicate when a target moving on a circular trajectory changed its luminance. The judged position of the luminance change was displaced from the true position in the direction of motion, indicating differences between the times-to-consciousness of motion and luminance change. Motion was processed faster than luminance change. The latency difference was more pronounced for a small (116–134 ms) than for a large luminance decrement (37 ms). The results show that first-order motion is perceived before an accurate representation of luminance is available. These findings are consistent with current accounts of the flash-lag effect. Two control experiments ruled out that the results were due to a general forward tendency. Localization of the target when an auditory signal was presented did not produce forward displacement, and the judged onset of motion was not shifted in the direction of motion.     

线索呈现的时空特性对表征动量的影响

为揭示注意对表征动量的影响机制,我们结合线索提示和表征动量范式,通过两个实验比较高、低相关线索分别在诱导期间与保持间隔呈现对表征动量的影响,结果发现：(1)高相关线索的时间特性主效应不显著,最终位置均发生边缘性的向前偏移。(2)低相关线索呈现在诱导期间时,表征动量显著;呈现在保持间隔时,发生向后偏移。这些表明,随着注意增大,表征动量减小;高相关线索更有利于定位,而低相关线索易受时间特性的影响。研究结果验证表征动量的双加工理论。     

The pointedness effect on representational momentum

An observer's memory for the final position of a moving object is shifted forward in the direction of that object's motion. It is called representational momentum (RM). This study addressed stimulus-specific effects on RM. In Experiment 1, participants showed larger memory shift for an object moving in its typical direction of motion than when it moved in a nontypical direction of motion. In Experiment 2, participants indicated larger memory shift for a pointed pattern moving in the direction of its point than when it moved in the opposite direction. In Experiment 3, we again examined the influences of knowledge about objects' typical motions and the pointedness of objects, because we did not control the shape (pointedness) of objects in Experiment 1. The results showed that only pointedness affected the magnitude of memory shift and that the effect was smaller than the momentum effect.     

运动空间定向判断中的方向偏差及飞行惯性

模拟客体起飞和降落运动,探讨飞行场景中不同运动位置、不同意义客体和运动方向下个体运动空间定向判断能力。结果表明：(1)对降落运动轨迹的判断正确率显著低于起飞运动;(2)无意义客体偏高轨迹的判断正确率显著小于偏低轨迹,表现出方向偏差;(3)飞行场景影响方向偏差的表现形式,当飞机降落运动时,易将偏低路径判断为与预设轨迹相同,而飞机起飞运动时,易将偏高路径判断为相同,表明降落时飞机被知觉为会向斜下方越飞越低,而起飞时飞机会向斜上方越飞越高,表现出飞行惯性。结论：运动空间定向判断受到重力表征及个体知识经验等共同影响,具有认知可渗透性。     

运动空间定向判断中的方向偏差及飞行惯性

模拟客体起飞和降落运动,探讨飞行场景中不同运动位置、不同意义客体和运动方向下个体运动空间定向判断能力。结果表明：(1)对降落运动轨迹的判断正确率显著低于起飞运动;(2)无意义客体偏高轨迹的判断正确率显著小于偏低轨迹,表现出方向偏差;(3)飞行场景影响方向偏差的表现形式,当飞机降落运动时,易将偏低路径判断为与预设轨迹相同,而飞机起飞运动时,易将偏高路径判断为相同,表明降落时飞机被知觉为会向斜下方越飞越低,而起飞时飞机会向斜上方越飞越高,表现出飞行惯性。结论：运动空间定向判断受到重力表征及个体知识经验等共同影响,具有认知可渗透性。     

The role of perception in the mislocalization of the final position of a moving target

The judged final position of a moving stimulus has been suggested to be shifted in the direction of motion because of mental extrapolation (representational momentum). However, a perceptual explanation is possible: The eyes overshoot the final position of the target, and because of a foveal bias, the judged position is shifted in the direction of motion. To test this hypothesis, the authors replicated previous studies, but instead of having participants indicate where the target vanished, the authors probed participants' perceptual focus by presenting probe stimuli close to the vanishing point. Identification of probes in the direction of target motion was more accurate immediately after target offset than it was with a delay. Another experiment demonstrated that judgments of the final position of a moving target are affected by whether the eyes maintain fixation or follow the target. The results are more consistent with a perceptual explanation than with a memory account.     

Eye movement as a cue to figure motion in anorthoscopic perception

When a figure moves behind a narrow aperture in an opaque surface, if it is perceived as a figure, its shape will often appear distorted. Under such anorthoscopic conditions, the speed or direction of the object's motion is ambiguous. However, when the observer simultaneously tracks a moving target, a figure is always perceived, and its precise shape is a function of the speed or direction of tracking. The figure is seen as moving with the speed or in the direction of the target. Thus, it is argued that eye movement serves as a cue to the figure's motion, which, in turn, determines its perceived length or orientation.     

飞行场景中表征动量的地标吸引效应和排斥效应

设置了安全和危险两种地标, 采用诱导运动范式考察了飞行场景中运动目标和关联地标的相对关系、目标运动方向及关联地标的意义特征和呈现时间对运动目标位置判断的影响。结果显示: (1)飞行场景中飞机的表征动量较强; (2) 趋近安全地标的表征动量大于远离安全地标的表征动量, 趋近危险地标的表征动量小于远离危险地标的表征动量, 安全地标呈现出地标吸引效应, 而危险地标呈现出地标排斥效应; (3) 高关联的安全和危险地标使飞机的表征动量不受运动方向影响; (4) 保持间隔期间呈现的安全和危险地标使飞机的表征动量增加。结论 :表征动量的地标效应受制于地标意义特征, 表征动量受到目标和地标之间的因果关系和情景意义的影响。     

Representational momentum contributes to motion induced mislocalization of stationary objects

The influence of a moving target on memory for the location of a briefly presented stationary object was examined. When the stationary object was aligned with the final portion of the moving target's trajectory, memory for the location of the stationary object was displaced forward (i.e., in the direction of motion of the moving target); the magnitude of forward displacement increased with increases in the velocity of the moving target, decreased with increases in the distance of the stationary object from the final location of the moving target, and increased and then decreased with increases in retention interval. It is suggested that forward displacement in memory for a stationary object aligned with the final portion of a moving target's trajectory reflects an influence of representational momentum of the moving target on memory for the location of the stationary object. Implications of the data for theories of representational momentum and motion induced mislocalization are discussed.     

Representational momentum in spatial hearing

The final position of a moving visual object usually appears to be displaced in the direction of motion. We investigated this phenomenon, termed representational momentum, in the auditory modality. In a dark anechoic environment, an acoustic target (continuous noise or noise pulses) moved from left to right or from right to left along the frontal horizontal plane. Listeners judged the final position of the target using a hand pointer. Target velocity was 8 degrees s(-1) or 16 degrees s(-1). Generally, the final target positions were localised as displaced in the direction of motion. With presentation of continuous noise, target velocity had a strong influence on mean displacement: displacements were stronger with lower velocity. No influence of sound velocity on displacement was found with motion of pulsed noise. Although these findings suggest that the underlying mechanisms may be different in the auditory and visual modality, the occurrence of displacements indicates that representational-momentum-like effects are not restricted to the visual modality, but may reflect a general phenomenon with judgments of dynamic events.     

Fast Responses of the Human Hand to Changes in Target Position

If a target toward which an individual moves his hand suddenly moves, he adjusts the movement of his hand accordingly. Does he use visual information on the target's velocity to anticipate where he will reach the target? These questions were addressed in the present study. Subjects (N = 6 in each of 4 experiments) were instructed to hit a disk with a rod as soon as it appeared on a screen. Trajectories of the hand toward stationary disks were compared with those toward disks that jumped leftward or rightward as soon as the subject's hand started moving toward the screen, and with those in which either the disk or the background started moving leftward or rightward. About 110 ms after the disk was suddenly displaced, the moving hand was diverted in the direction of the perturbation. When the background moved, the disk's perceived position shifted in the direction in which the background was moving, but the disk appeared to be moving in the opposite direction. When hitting such disks, subjects adjusted their movement in accordance with the perceived position, rather than moving their hand in the direction of the perceived motion in anticipation of the disk's future displacement. Thus, subjects did not use the perceived velocity to anticipate where they would reach the target but responded only to the change in position