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.     

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.     

Representational momentum in memory for pitch

When a visual pattern is displayed at successively different orientations such that a rotation or translation is implied, an observer's memory for the final position is displaced forward. This phenomenon of representational momentum shares some similarities with physical momentum. For instance, the amount of memory shift is proportional to the implied velocity of the inducing display; representational momentum is specifically proportional to the final, not the average, velocity; representational momentum follows a continuous stopping function for the first 250 ms or so of the retention interval. In a previous paper (Kelly & Freyd, 1987) we demonstrated a forward memory asymmetry using implied changes in pitch, for subjects without formal musical training. In the current paper we replicate our earlier finding and show that the forward memory asymmetry occurs for subjects with formal musical training as well (Experiment 1). We then show the structural similarity between representational momentum in memory for pitch with previous reports of parametric effects using visual stimuli. We report a velocity effect for auditory momentum (Experiment 2), we demonstrate specifically that the velocity effect depends on the implied acceleration (Experiment 3), and we show that the stopping function for auditory momentum is qualitatively the same as that for visual momentum (Experiment 4). We consider the implications of these results for theories of mental representation.     

Representational momentum and event course anticipation in the perception of implied periodical motions.

After viewing an object in an implied rotation, subjects' short-term visual memory for the object's position is distorted in the direction of rotation. Previous accounts of this representational momentum effect have emphasized the analogy to physical momentum. This study provides a more general perspective: Position memory is influenced by anticipatory processes related to the future event course. In Experiment 1, subjects are presented with an implied periodical event in which a rectangle rotates back and forth. When a direction change in the implied rotation can be anticipated, memory distortion size drops back to zero. Experiment 2 rejects an alternative explanation for the findings of Experiment 1 in terms of enhanced position memory caused by repeated presentations of the memory pattern orientation within the same trial. In Experiment 3, the periods of the implied event are marked by changes in velocity rather than direction. The anticipation of a sudden velocity increase leads to a larger memory shift. We conclude that the perceptual system anticipates the event course on the basis of a representation of the higher order event structure rather than the local motion characteristics.     

Can representational trajectory reveal the nature of an internal model of gravity?

The memory for the vanishing location of a horizontally moving target is usually displaced forward in the direction of motion (representational momentum) and downward in the direction of gravity (representational gravity). Moreover, this downward displacement has been shown to increase with time (representational trajectory). However, the degree to which different kinematic events change the temporal profile of these displacements remains to be determined. The present article attempts to fill this gap. In the first experiment, we replicate the finding that representational momentum for downward-moving targets is bigger than for upward motions, showing, moreover, that it increases rapidly during the first 300 ms, stabilizing afterward. This temporal profile, but not the increased error for descending targets, is shown to be disrupted when eye movements are not allowed. In the second experiment, we show that the downward drift with time emerges even for static targets. Finally, in the third experiment, we report an increased error for upward-moving targets, as compared with downward movements, when the display is compatible with a downward ego-motion by including vection cues. Thus, the errors in the direction of gravity are compatible with the perceived event and do not merely reflect a retinotopic bias. Overall, these results provide further evidence for an internal model of gravity in the visual representational system.     

Prior probabilities and representational momentum

In many previous experiments on representational momentum (in which memory for the final location of a moving target is displaced in the direction of target motion), participants judged whether a probe presented after a target vanished was at the same location where that target vanished or at a different location. The experiments reported here manipulated the actual or expected prior probability a same response to such a probe would be correct. In Experiment 1, a same response was correct on 10%, 30%, 50%, 70%, or 90% of the trials, but observers were not instructed regarding these probabilities. In Experiment 2, a same response was correct on 11% of the trials, but different groups of participants were instructed that a same response would be correct on 10%, 30%, 50%, 70%, or 90% of the trials. Probabilities of a same response to different probe positions, weighted mean estimates of representational momentum, hit rates and false alarm rates, and d′ and ß are reported. Representational momentum occurred in all conditions but was not influenced by actual or expected prior probability a same response would be correct. The data suggest representational momentum does not result from changes in sensitivity, and a distinction between performance bias and competence bias is introduced.     

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.     

A Clockwork Orange: Compensation opposing momentum in memory for location

Libet, Gleason, Wright, and Pearl's (1983; Libet, 1985) influential work using a clock-watching task suggests that voluntary actions are initiated in motor cortex prior to the point where the participant claims to have initiated that action. Joordens, van Duijn, and Spalek (2002) showed that a bias exists in this task with respect to the participants' reports of initiation times. Joordens et al. assumed that this bias was primarily due to motion cues that are very much like those used to elicit phenomena such as representational momentum. In the present Experiment 1, it is demonstrated that this bias disappears when a mouse-click response is used in place of a temporal-order judgment. This finding, however, is actually more confusing than clarifying given that the procedural parallels with representational momentum are still present and should be supporting a bias. In the three subsequent experiments the view that a bias is indeed present, but that it is opposed by an opposite-acting compensation process, is proposed and tested. Implications for both representational momentum and for the general use of clock-watching tasks (e.g., Libet et al., 1983) are highlighted.     

Representational momentum in older adults

Humans have a tendency to perceive motion even in static images that simply “imply” movement. This tendency is so strong that our memory for actions depicted in static images is distorted in the direction of implied motion - a phenomenon known as representational momentum (RM). In the present study, we created an RM display depicting a pattern of implied (clockwise) rotation of a rectangle. Young adults viewers’ memory of the final position of the test rectangle was biased in the direction of continuing rotation, but older adults did not show a similar memory bias. We discuss several possible explanations for this group difference, but argue that the failure of older adults to shown an RM effect most likely reflects age-related changes in areas of the brain involved in processing real and implied motion.     

The relationship between mental rotation and representational momentum

Two experiments explored a possible relationship between mental rotation and representational momentum, a task in which participants were asked to remember an object's position following a sequence of images implying motion. Typically, participants misremember the position as distorted forward along the implied trajectory. If representational momentum relies on mental imagery, the magnitude of memory distortion in a representational momentum task should be positively correlated with the rate of mental rotation. As predicted, faster mental rotation rates and larger memory distortions for object position were observed for rotational axes aligned with the viewers' coordinate system. In addition, participants with slower mental rotation rates produced smaller memory distortions in the implied-event task.     

质量表征和眼动过度追踪对表征动量的影响

人们对运动目标最终位置的记忆常常会向运动方向发生偏移, 这种偏移被称为“表征动量”。现有研究对表征动量的解释涉及从低水平的知觉加工到高水平的认知加工等多个方面。本研究采用不同材质和滚动声音的球体作为刺激材料, 考察高水平的质量表征对表征动量的影响以及知觉水平的眼动信息在其中的作用。实验1探讨了对目标质量的主观表征对眼动追踪和表征动量的影响。结果显示, 质量表征会同时影响眼动追踪和表征动量。实验2通过不同的提示线索控制眼动追踪, 进一步探讨眼动过度追踪对表征动量的影响。我们发现, 非自然追踪的条件下, 表征动量会减小, 且质量表征对表征动量的影响不再显著。本研究结果表明, 高水平的质量表征对表征动量的影响会通过知觉水平的眼动过度追踪起作用; 然而, 表征动量还受其它因素影响, 眼动信息并非决定表征动量的唯一因素。     

Visual memory for moving scenes

In the present study, memory for picture boundaries was measured with scenes that simulated self-motion along the depth axis. The results indicated that boundary extension (a distortion in memory for picture boundaries) occurred with moving scenes in the same manner as that reported previously for static scenes. Furthermore, motion affected memory for the boundaries but this effect of motion was not consistent with representational momentum of the self (memory being further forward in a motion trajectory than actually shown). We also found that memory for the final position of the depicted self in a moving scene was influenced by properties of the optical expansion pattern. The results are consistent with a conceptual framework in which the mechanisms that underlie boundary extension and representational momentum (a) process different information and (b) both contribute to the integration of successive views of a scene while the scene is changing.     

Visual memory for moving scenes

In the present study, memory for picture boundaries was measured with scenes that simulated self-motion along the depth axis. The results indicated that boundary extension (a distortion in memory for picture boundaries) occurred with moving scenes in the same manner as that reported previously for static scenes. Furthermore, motion affected memory for the boundaries but this effect of motion was not consistent with representational momentum of the self (memory being further forward in a motion trajectory than actually shown). We also found that memory for the final position of the depicted self in a moving scene was influenced by properties of the optical expansion pattern. The results are consistent with a conceptual framework in which the mechanisms that underlie boundary extension and representational momentum (a) process different information and (b) both contribute to the integration of successive views of a scene while the scene is changing.     

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.     

速度知识和表征动量

通过3个实验探索速度知识和表征动量的关系。3个实验均使用2（速度知识：快、慢）×2（运动方向：左、右）的两因素实验设计,采用诱导运动范式,因变量为偏移加权均数。实验1使用汽车和自行车作为刺激材料,发现两者的前移量无差异;实验2使用人奔跑和站立姿势作为刺激材料,发现奔跑的前移量大于站立的前移量;实验3是控制实验,发现实验2的结果不是由水平视角差异造成的。结论：在有效启动速度概念的情况下,速度知识可以影响表征动量,但其影响可能相对微弱。     

Larger forward memory displacement in the direction of gravity

An observer's memory for the final position of a moving stimulus is shifted forward in the direction of its motion. Observers in an upright posture typically show a larger forward memory displacement for a physically downward motion than for a physically upward motion of a stimulus (representational gravity; Hubbard & Bharucha, 1988). We examined whether representational gravity occurred along the environmentally vertical axis or the egocentrically vertical axis. In Experiment 1 observers in either upright or prone postures viewed egocentrically upward and downward motions of a stimulus. Egocentrically downward effects were observed only in the upright posture. In Experiment 2 observers in either upright or prone postures viewed approaching and receding motions of a stimulus along the line of sight. Only in the prone posture did the receding motion produce a larger forward memory displacement than the approaching motion. These results indicate that representational gravity depends not on the egocentric axis but on the environmental axis.     

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.     

Environmental invariants in the representation of motion: Implied dynamics and representational momentum,gravity, friction,and centripetal force

Memory for the final position of a moving target is often shifted or displaced from the true final position of that target. Early studies of this memory shift focused on parallels between the momentum of the target and the momentum of the representation of the target and called this displacementrepresentational momentum, but many factors other than momentum contribute to the memory shift. A consideration of the empirical literature on representational momentum and related types of displacement suggests there are at least four different types of factors influencing the direction and magnitude of such memory shifts: stimulus characteristics (e.g., target direction, target velocity), implied dynamics and environmental invariants (e.g., implied momentum, gravity, friction, centripetal force), memory averaging of target and nontarget context (e.g., biases toward previous target locations or nontarget context), and observers’ expectations (both tacit and conscious) regarding future target motion and target/context interactions. Several theories purporting to account for representational momentum and related types of displacement are also considered.     

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。     

Illusory motion and representational momentum

When a moving target vanishes abruptly, participants judge its final position as being ahead of its actual final position, in the direction of motion (representational momentum; Freyd & Finke, 1984). In the present study, we presented illusory motion and examined whether or not forward displacement was affected by the perceived direction and speed of the target. Experiments 1A and 1B showed that an illusory direction of movement of a target was perceived, and Experiment 2 showed that an illusory speed of a moving target was observed. However, neither the direction nor the magnitude of forward displacement was affected by these illusions. Therefore, it was suggested that the mechanism underlying forward displacement (or some extrapolation processing) uses different motion signals than does the perceptual mechanism.