Object updating and the flash-lag effect

Flash lag is a misperception of spatial relations between a moving object and a briefly flashed stationary one. This study began with the observation that the illusion occurs when the moving object continues following the flash, but is eliminated if the object's motion path ends with the flash. The data show that disrupting the continuity of the moving object, via a transient change in size or color, also eliminates the illusion. We propose that this is because a large feature change leads to the formation of a second object representation. Direct evidence for this proposal is provided by the results for a corollary perceptual feature of the disruption in object continuity: the perception of two objects, rather than only one, on the motion path.     

Representational momentum and the flash‐lag effect

Representational momentum (RM) is a distortion where the final orientation of a moving object is misremembered as further along its trajectory. Experiments reported here examine RM when an additional object was flashed just as the moving object disappeared. When the task was to judge the flashed object, participants reported that the flash appeared to lag behind (flash‐lag effect; FLE). When the task was to judge the moving object, larger forward distortions for the moving object were found when the flash was present, despite previous evidence that the FLE depends on the moving object's continued presence. The results suggest that some part of the FLE depends upon what precedes the flash. In addition, equivalent RM was observed for implied and smoothly animated events, a possible limit to the velocity effect for RM was found, and larger positive distortions were found for downward rotations.     

闪光滞后效应并非知觉延迟差异所致

闪光滞后效应(flash-lag effect)是指在与运动物体一致的位置上呈现闪光(flash),知觉上闪光落后于运动物体的视错觉。延迟差异理论认为,产生该现象的原因是视觉系统加工闪光的速度比加工运动物体慢。根据该理论,作者预测:如采用知觉加工速度更快(或更慢)的客体替代闪光,应能相应地产生更小(或更大)的闪光滞后效应。为了检验该预测,作者以"客体突现"(onset)和"客体消失"(offset)替代闪光滞后实验中的闪光,结果发现,"突现"的知觉滞后大于"消失",但时序判断任务表明"突现"的知觉延迟比"消失"短。该结果并不支持延迟差异理论。     

Saccades reveal that allocentric coding of the moving object causes mislocalization in the flash-lag effect

The flash-lag effect is a visual misperception of a position of a flash relative to that of a moving object: Even when both are at the same position, the flash is reported to lag behind the moving object. In the present study, the flash-lag effect was investigated with eye-movement measurements: Subjects were required to saccade to either the flash or the moving object. The results showed that saccades to the flash were precise, whereas saccades to the moving object showed an offset in the direction of motion. A further experiment revealed that this offset in the saccades to the moving object was eliminated when the whole background flashed. This result indicates that saccadic offsets to the moving stimulus critically depend on the spatially distinctive flash in the vicinity of the moving object. The results are incompatible with current theoretical explanations of the flash-lag effect, such as the motion extrapolation account. We propose that allocentric coding of the position of the moving object could account for the flash-lag effect.     

A New Tactile Illusion: Temporal Limits on the Processing of Spatiotemporal Patterns

A novel illusion was observed when 12 tactile point-stimulators arranged in a circle were sequentially activated so that each quadrant was first traced in a clockwise manner, then counterclockwise, and again in a clockwise manner, after which the next quadrant was similarly traced. Under certain temporal conditions this stimulus pattern was experienced as a point moving through an overall circular path but looping inwardly about once per quadrant. The effects of variations in rate of presentation of such stimuli were investigated by having subjects make drawings of their perceptual experiences. Three skin surfaces were used (palm, fingers, and forearm), and all produced similar results except for lower confidence and reliability of drawings made from forearm stimulation. Pattern presentation rate, however, had a consistent and powerful effect, with the looping illusion most frequently observed at rates around 25 pattern points per s and with different perceptual organizations dominating as rates departed widely from this optimum. The illusory perceptual organizations were interpreted as compromises between past and present stimulation necessitated by the relative slowness of tactile processing of spatio-temporal patterns.     

A new tactile illusion: temporal limits on the processing of spatiotemporal patterns

A novel illusion was observed when 12 tactile point-stimulators arranged in a circle were sequentially activated so that each quadrant was first traced in a clockwise manner, then counterclockwise, and again in a clockwise manner, after which the next quadrant was similarly traced. Under certain temporal conditions this stimulus pattern was experienced as a point moving through an overall circular path but looping inwardly about once per quandrant. The effects of variations in rate of presentation of such stimuli were investigated by having subjects make drawings of their perceptual experiences. Three skin surfaces were used (palm, fingers, and forearm), and all produced similar results except for lower confidence and reliability of drawings made from forearm stimulation. Pattern presentation rate, however, had a consistent and powerful effect, with the looping illusion most frequently observed at rates around 25 pattern points per s and with different perceptual organizations dominating as rates departed widely from this optimum. The illusory perceptual organizations were interpreted as compromises between past and present stimulation necessitated by the relative slowness of tactile processing of spatiotemporal patterns.     

Temporal ventriloquism: sound modulates the flash-lag effect

A sound presented in close temporal proximity to a visual stimulus can alter the perceived temporal dimensions of the visual stimulus (temporal ventriloquism). In this article, the authors demonstrate temporal ventriloquism in the flash-lag effect (FLE), a visual illusion in which a flash appears to lag relative to a moving object. In Experiment 1, the magnitude and the variability of the FLE were reduced, relative to a silent condition, when a noise burst was synchronized with the flash. In Experiment 2, the sound was presented before, at, or after the flash (+/- approximately 100 ms), and the size of the FLE varied linearly with the delay of the sound. These findings demonstrate that an isolated sound can sharpen the temporal boundaries of a flash and attract its temporal occurrence.     

Differential use of distance and location information for spatial localization

Five experiments are reported in which subjects judged the movement or spatial location of a visible object that underwent a combination of real and induced (illusory) motion. When subjects attempted to reproduce the distance that the object moved by moving their unseen hands, they were more affected by the illusion than when they pointed to the object's perceived final location. Furthermore, pointing to the final location was more affected by the illusion when the hand movement began from the same position as that at which the object initially appeared, as compared with responses that began from other positions. The results suggest that people may separately encode two distinct types of spatial information: (1) information about the distance moved by an object and (2) information about the absolute spatial location of the object. Information about distance is more susceptible to the influence of an induced motion illusion, and people appear to rely differentially on the different types of spatial information, depending on features of the pointing response. The results have important implications for the mechanisms that underlie spatially oriented behavior in general.     

Sound and vision

When a brief flash appears at the same position as a moving object, the flash is perceived to lag behind. This so-called flash-lag effect tells us something about the perception of space and time: where is the moving object when the flash appears? A recent paper by Alais and Burr on auditory and crossmodal flash-lag effects indicates that our (often implicit) models of the perception of space and time might be flawed.     

内源性空间注意对声音诱发闪光错觉的影响

采用经典的声音诱发闪光错觉范式,通过操纵集中和分散的空间注意的方式,考察内源性空间注意和刺激出现视野位置的交互作用对多感觉整合中听觉主导效应的影响。结果发现：(1)当空间注意处于分散状态时,下视野的裂变错觉量显著大于上视野,而集中条件下则没有差异。(2)闪光出现的位置是否随机不会影响裂变错觉。研究说明了声音诱发闪光错觉中的裂变错觉只会受到内源性空间注意和视野位置交互作用的影响。     

Looking ahead: Attending to anticipatory locations increases perception of control

When people manipulate a moving object, such as writing with a pen or driving a car, they experience their actions as intimately related to the object’s motion, that is they perceive control. Here, we tested the hypothesis that observers would feel more control over a moving object if an unrelated task drew attention to a location to which the object subsequently moved. Participants steered an object within a narrow path and discriminated the color of a flash that appeared briefly close to the object. Across two experiments, participants provided higher ratings of perceived control when an object moved over a flash’s location than when an object moved away from a flash’s location. This result suggests that we use the location of spatial attention to determine the perception of control. If an object goes where we are attending, we feel like we made it go there.     

Visual grouping by motion precedes the relative localization between moving and flashed stimuli

A flashed stimulus is perceived as spatially lagging behind a moving stimulus when they are spatially aligned. When several elements are perceptually grouped into a unitary moving object, a flash presented at the leading edge of the moving stimulus suffers a larger spatial lag than a flash presented at the trailing edge (K. Watanabe. R. Nijhawan. B. Khurana, & S. Shimojo. 2001). By manipulation of the flash onset relative to the motion onset, the present study investigated the order of perceptual operations of visual motion grouping and relative visual localization. It was found that the asymmetric mislocalization was observed irrespective of physical and/or perceptual temporal order between the motion and flash onsets. Thus, grouping by motion must be completed to define the leading-trailing relation in a moving object before the visual system explicitly represents the relative positions of moving and flashed stimuli.     

集中和分散注意对多感觉整合中听觉主导效应的影响

听觉主导效应是指多感觉通道信息整合过程中,听觉通道中的信息得到优先加工,从而主导其他感觉通道的信息。研究采用经典的声音诱发闪光错觉的范式,通过两个实验操纵了注意资源的分配方式以及实验任务难度,考察了主动注意听觉通道的声音刺激对声音诱发闪光错觉产生的影响,以及任务难度对声音诱发闪光错觉的影响。结果发现:(1)裂变错觉会受到注意资源分配程度的影响,但是融合错觉则不然;(2)任务难度既不会影响裂变错觉,也不会影响融合错觉。说明了分散注意能够影响听觉主导效应中的裂变错觉,并且这种主导效应与任务难度无关。     

Movement aftereffects contingent on color,intensity, and pattern

We have found contingent movement aftereffects (CMAEs) lasting several days, contingent upon the color, intensity, and stripe width of moving patterns. Ss adapted for 10 min to a patterned disk rotating clockwise under red light, alternating every 10 sec with counterclockwise under green light. When stopped, the disk then appeared to rotate counterclockwise under red light and clockwise under green light. The effect lasted only a second or two, reappearing each time the field’s color was changed. But it increased in strength over the first 1/2 hand was still present 1 or 2 days later. Color transposition effects were found: after adaptation to red-clockwise (long wavelength) alternating with green-counterclockwise (short wavelength), a stationary yellow (long wavelength) test field appeared to rotate counterclockwise and a blue (short wavelength) field appeared to rotate clockwise. Relative, not absolute, color of the test triggered the CMAE. Similar CMAEs and transposition effects were produced by pairing direction of movement with intensity, with width of moving stripes and with orientation of a stationary grating projected onto a rotating patterned disk.     

空间相对位置效应的时间特征

用方位箭头作探测刺激,研究故事阅读产生的想象空间中物体搜索任务的反应时模式。结果发现：(1)方位箭头的指向对物体搜索有影响,反应时模式为：左=右=前＜后,说明方位箭头作探测刺激时的物体搜索过程不涉及人一物空间关系的转换;(2)目标物体与注意物体的相对位置对物体搜索有影响,反应时模式为注意点＜注意点对面＜注意点左侧=注意点右侧,说明相对位置效应与人物空间关系的转换无关。本研究结果支持了两阶段理论。     

Intuitive physics: the straight-down belief and its origin

This study examines the nature and origin of a common misconception about moving objects. We first show through the use of pencil-and-paper problems that many people erroneously believe that an object that is carried by another moving object (e.g., a ball carried by a walking person) will, if dropped, fall to the ground in a straight vertical line. (In fact, such an object will fall forward in a parabolic arc.) We then demonstrate that this "straight-down belief" turns up not only on pencil-and-paper problems but also on a problem presented in a concrete, dynamic fashion (Experiment 1) and in a situation in which a subject drops a ball while walking (Experiment 2). We next consider the origin of the straight-down belief and propose that the belief may stem from a perceptual illusion. Specifically, we suggest that objects dropped from a moving carrier may be perceived as falling straight down or even backward, when in fact they move forward as they fall. Experiment 3, in which subjects view computer-generated displays simulating situations in which a carried object is dropped, and Experiment 4, in which subjects view a videotape of a walking person dropping an object, provide data consistent with this "seeing is believing" hypothesis.     

Comparing mislocalizations with moving stimuli: The Fröhlich effect,the flash-lag,and representational momentum

When observers are asked to localize the onset or the offset position of a moving target, they typically make localization errors in the direction of movement. Similarly, when observers judge a moving target that is presented in alignment with a flash, the target appears to lead the flash. These errors are known as the Fröhlich effect, representational momentum, and flash-lag effect, respectively. This study compared the size of the three mislocalization errors. In Experiment 1, a flash appeared either simultaneously with the onset, the mid-position, or the offset of the moving target. Observers then judged the position where the moving target was located when the flash appeared. Experiments 2 and 3 are exclusively concerned with localizing the onset and the offset of the moving target. When observers localized the position with respect to the point in time when the flash was presented, a clear mislocalization in the direction of movement was observed at the initial position and the mid-position. In contrast, a mislocalization opposite to movement direction occurred at the final position. When observers were asked to ignore the flash (or when no flash was presented at all), a reduced error (or no error) was observed at the initial position and only a minor error in the direction of the movement occurred at the final position. An integrative model is proposed, which suggests a common underlying mechanism, but emphasizes the specific processing components of the Fröhlich effect, flash-lag effect, and representational momentum.     

The reversed Müller-Lyer illusion and figure-ground organization theory.

When the shaft is shortened and reaches neither of the vertices of the two pairs of wings, a reversed Müller-Lyer illusion is observed: a shaft between inward-pointing wings appears to be longer than a shaft between the outward-pointing wings. In this paper it is examined whether this illusion can be explained in terms of figure-ground organization. A circle was used as the focal area, instead of a shaft or a pair of dots, so that the figure-ground character could be seen more definitely in this focal area. The apparent size of the focal circle was measured under different conditions with three variables (enclosure, wings direction, and depth). The focal circle appeared to be largest in the condition where the circle should appear most readily as a hole, ie in the single, wings-in, space condition. The circle appeared to be smallest in the condition where the circle should appear most readily as a disc, ie in the separate, wings-out, object condition. This is consistent with an explanation of the usual, as well as the reversed, Müller-Lyer illusion in terms of figure-ground organization theory.     

Animacy and propulsion in infancy: Tracking,waving and reaching to self-propelled and induced moving objects

Infants from 16 to 20 weeks were videotaped while being presented with objects traversing a 60 cm distance. Four conditions were tested: (1) induced movement, holding the object; (2) induced movement, pushing the object; (3) self-propelled mechanical movement, object moving by an internal clockwork; (4) self-propelled biological movement, animate object moving by internal impulse. In tracking, the self-propelled but inanimate and mechanically moving object with the more straight and predictable trajectory attracted most visual attention. In arm movements, the self-propelled but relatively unpredictably moving animate object was reliably distinguished from inanimate objects. It appeared that the action system was less dependent on objects taking a straight and predictable course. Emerging with the onset of goal-directed reaches, the distinction of an internal locus of propulsion in objects was overriding the nearly exclusive response towards animacy occurring in waving. Thus, a distinction of different types of object motion could be found in infants’ developing action system.     

Judgments of synchrony between auditory and moving or still visual stimuli.

The flash-lag effect is a visual illusion wherein intermittently flashed, stationary stimuli seem to trail after a moving visual stimulus despite being flashed synchronously. We tested hypotheses that the flash-lag effect is due to spatial extrapolation, shortened perceptual lags, or accelerated acquisition of moving stimuli, all of which call for an earlier awareness of moving visual stimuli over stationary ones. Participants judged synchrony of a click either to a stationary flash of light or to a series of adjacent flashes that seemingly bounced off or bumped into the edge of the visual display. To be judged synchronous with a stationary flash, audio clicks had to be presented earlier--not later--than clicks that went with events, like a simulated bounce (Experiment 1) or crash (Experiments 2-4), of a moving visual target. Click synchrony to the initial appearance of a moving stimulus was no different than to a flash, but clicks had to be delayed by 30-40 ms to seem synchronous with the final (crash) positions (Experiment 2). The temporal difference was constant over a wide range of motion velocity (Experiment 3). Interrupting the apparent motion by omitting two illumination positions before the last one did not alter subjective synchrony, nor did their occlusion, so the shift in subjective synchrony seems not to be due to brightness contrast (Experiment 4). Click synchrony to the offset of a long duration stationary illumination was also delayed relative to its onset (Experiment 5). Visual stimuli in motion enter awareness no sooner than do stationary flashes, so motion extrapolation, latency difference, and motion acceleration cannot explain the flash-lag effect.