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.     

Displacement in depth: Representational momentum and boundary extension

Memory for targets moving in depth and for stationary targets was examined in five experiments. Memory for targets moving in depth was displaced behind the target with slower target velocities (longer ISIS and retention intervals) and beyond the target with faster target velocities (shorter ISIS and retention intervals), and the overall magnitude of forward displacement for motion in depth was less than the overall magnitude of forward displacement for motion in the picture plane. Memory for stationary targets was initially displaced away from the observer, but memory for smaller stationary targets was subsequently displaced toward the observer and memory for larger stationary targets was subsequently displaced away from the observer; memory for the top or bottom edge of a stationary target was displaced inside the target perimeter. The data are consistent with Freyd and Johnson's (1987) two-component model of the time course of representational momentum and with Intraub et al.'s (1992) two-component model of boundary extension.     

Boundary extension: Findings and theories

A view of a scene is often remembered as containing information that might have been present just beyond the actual boundaries of that view, and this is referred to as boundary extension. Characteristics of the view (e.g., scene or nonscene; close-up or wide-angle; whether objects are cropped, static, or in motion, emotionally neutral or emotionally charged), display (e.g., aperture shape and size; target duration; retention interval; whether probes of memory involve magnification/minification or change in physical distance), and observer (e.g., allocation of attention; age; planned fixation, gaze direction, and eye movements; monocular or binocular viewing; prior exposure; neurological correlates) that influence boundary extension are reviewed. Proposed mechanisms of boundary extension (perceptual, memory, or motion schema; extension–normalization; attentional selection; errors in source monitoring) are discussed, and possible relationships of boundary extension to other cognitive processes (e.g., representational momentum; remembered distance and remembered size; amodal completion; transsaccadic memory) are briefly addressed.     

Memory for moving and static images

Despite the substantial interest in memory for complex pictorial stimuli, there has been virtually no research comparing memory for static scenes with that for their moving counterparts. We report that both monochrome and color moving images are better remembered than static versions of the same stimuli at retention intervals up to one month. When participants studied a sequence of still images, recognition performance was the same as that for single static images. These results are discussed within a theoretical framework which draws upon previous studies of scene memory, face recognition, and representational momentum.     

Anticipatory spatial representation of natural scenes: Momentum without movement?

Does mental representation of the immediate past contain anticipatory projections of the future? In cases of representational momentum (RM), the last remembered location of a moving object is displaced farther along its path of motion. In boundary extension (BE), the remembered view of a scene expands to include a region just outside the boundaries of the original view. Both are "errors", yet they make remarkably good predictions about the real world. The factors affecting these phenomena, the boundary conditions for their occurrence, and their generality to non-visual senses (audition or haptics) are reviewed to determine if RM and BE are fundamentally related. In contrast to Hubbard's (1995b) suggestion that they may share a common underlying mechanism, it is proposed instead that RM and BE are related in a more general sense and may be different instantiations of the dynamic nature of mental representation.     

Spatial asymmetries in viewing and remembering scenes: Consequences of an attentional bias?

Given a single fixation, memory for scenes containing salient objects near both the left and right view boundaries exhibited a rightward bias in boundary extension (Experiment 1). On each trial, a 500-msec picture and 2.5-sec mask were followed by a boundary adjustment task. Observers extended boundaries 5% more on the right than on the left. Might this reflect an asymmetric distribution of attention? In Experiments 2A and 2B, free viewing of pictures revealed that first saccades were more often leftward (62%) than rightward (38%). In Experiment 3, 500-msec pictures were interspersed with 2.5-sec masks. A subsequent object recognition memory test revealed better memory for left-side objects. Scenes were always mirror reversed for half the observers, thus ruling out idiosyncratic scene compositions as the cause of these asymmetries. Results suggest an unexpected leftward bias of attention that selectively enhanced the representations, causing a smaller boundary extension error and better object memory on the views’ left sides.     

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。     

Anticipating action in complex scenes

In four experiments we explored the accuracy of memory for human action using displays with continuous motion. In Experiment 1, a desktop virtual environment was used to visually simulate ego‐motion in depth, as would be experienced by a passenger in a car. Using a task very similar to that employed in typical studies of representational momentum we probed the accuracy of memory for an instantaneous point in space/time, finding a consistent bias for future locations. In Experiment 2, we used the same virtual environment to introduce a new “interruption” paradigm in which the sensitivity to displacements during a continuous event could be assessed. Thresholds for detecting displacements in ego‐position in the direction of motion were significantly higher than those opposite the direction of motion. In Experiments 3 and 4 we extended previous work that has shown anticipation effects for frozen action photographs or isolated human figures by presenting observers with short video sequences of complex crowd scenes. In both experiments, memory for the stopping position of the video was shifted forward, consistent with representational momentum. Interestingly, when the video sequences were played in reverse, the magnitude of this forward bias was larger. Taken together, the results of all four experiments suggest that even when presented with complex, continuous motion, the visual system may sometimes try to anticipate the outcome of our own and others' actions.     

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.     

Boundary distortions for neutral and emotional pictures

In two experiments, we examined Safer, Christianson, Autry, and Osterlund's (1998) claim that when emotional material is remembered, tunnel memory (i.e., the tendency to remember less of a scene than was actually shown) occurs. In Experiment 1, 81 undergraduate students drew photographs from memory after having briefly seen either four neutral or four emotional photographs. Both neutral and emotional drawings revealed boundary extension (i.e., the tendency to remember more of a scene than was actually shown). Experiment 2 relied on the camera distance paradigm (Intraub, Bender, & Mangels, 1992). In a recognition test, 60 undergraduate students judged the camera distance of previously seen neutral or emotional photographs. The majority of them demonstrated accurate judgments and neither extended nor restricted picture boundaries. Those participants who made an error more often displayed a boundary extension than a tunnel memory error. Taken together, our results suggest that boundary extension for neutral and emotional photographs is a more robust phenomenon than its counterpart, tunnel memory.     

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.     

Boundary extension: the role of magnification, object size, context, and binocular information

Boundary extension is a tendency to remember close-up scenes as if they extended beyond the occluding boundaries. The authors explored the contributing factors using brief retention intervals and computer-generated images. Boundary extension turns out to be more complex than previously thought and is not linked to the effects of image magnification and field-of-view changes. Although this is consistent with the idea that boundary extension is the product of the activation of a mental schema that provides information of what is likely to exist outside the picture boundaries, the authors also found that properties of the object at the center of the picture can affect boundary extension independently of the information at the boundaries. In a test of boundary extension using stereograms, the effect does not seem to depend on amount of perceived depth, suggesting a weaker link to perception of space than previously hypothesized.     

Representational momentum in aviation

The purpose of this study was to examine the effects of expertise on motion anticipation. We conducted 2 experiments in which novices and expert pilots viewed simulated aircraft landing scenes. The scenes were interrupted by the display of a black screen and then started again after a forward or backward shift. The participant's task was to determine whether the moving scene had been shifted forward or backward. A forward misjudgment of the final position of the moving scene was interpreted as a representational momentum (RM) effect. Experiment 1 showed that an RM effect was detected only for experts. The lack of motion anticipation on the part of novices is a surprising result for the RM literature. It could be related to scene unfamiliarity, encoding time, or shift size. Experiment 2 was run with novices only. It was aimed at testing the potential impact of 2 factors on the RM effect: scene encoding time and shift size. As a whole, the results showed that encoding time and shift size are important factors in anticipation processes in realistic dynamic situations.     

Constraints on spatial extrapolation in the mental representation of scenes: View-boundaries vs. object-boundaries

Viewers remember seeing information from outside the boundaries of a scene (boundary extension; BE). To determine if view-boundaries have a special status in scene perception, we sought to determine if object-boundaries would yield the same effect. In Experiment 1 eight “bird's-eye view” photographs containing single object clusters (a smaller object on top of a larger one) were presented. After the presentation, participants reconstructed four scenes by selecting among five different-sized cutouts of each object. BE occurred between the view-boundaries and the object cluster, but not between the smaller object and the larger object's boundaries. There was no consistent effect of the larger object's boundaries. Experiment 2 replicated these results using a drawing task. BE does not occur whenever a border surrounds an object, it occurs when the border signifies the edge of the view. We propose the BE reflects anticipatory representation of scene structure that supports scene comprehension and view integration.     

Anticipatory scene representation in preschool children's recall and recognition memory

Behavioral and neuroscience research on boundary extension (false memory beyond the edges of a view of a scene) has provided new insights into the constructive nature of scene representation, and motivates questions about development. Early research with children (as young as 6–7 years) was consistent with boundary extension, but relied on an analysis of spatial errors in drawings which are open to alternative explanations (e.g. drawing ability). Experiment 1 replicated and extended prior drawing results with 4–5‐year‐olds and adults. In Experiment 2, a new, forced‐choice immediate recognition memory test was implemented with the same children. On each trial, a card (photograph of a simple scene) was immediately replaced by a test card (identical view and either a closer or more wide‐angle view) and participants indicated which one matched the original view. Error patterns supported boundary extension; identical photographs were more frequently rejected when the closer view was the original view, than vice versa. This asymmetry was not attributable to a selection bias (guessing tasks; Experiments 3–5). In Experiment 4, working memory load was increased by presenting more expansive views of more complex scenes. Again, children exhibited boundary extension, but now adults did not, unless stimulus duration was reduced to 5 s (limiting time to implement strategies; Experiment 5). We propose that like adults, children interpret photographs as views of places in the world; they extrapolate the anticipated continuation of the scene beyond the view and misattribute it to having been seen. Developmental differences in source attribution decision processes provide an explanation for the age‐related differences observed.     

Seeking the boundary of boundary extension

Boundary extension (BE) is a remarkably consistent visual memory error in which participants remember seeing a more wide-angle image of a scene than was actually viewed (Intraub & Richardson, Journal of Experimental Psychology: Learning, Memory, and Cognition 15:179–187, 1989). Multiple stimulus factors are thought to contribute to the occurrence of BE, including object recognition, conceptual knowledge of scenes, and amodal perception at the view boundaries (Intraub, Wiley Interdisciplinary Reviews: Cognitive Science 3:117–127, 2012). In the present study, we used abstract scenes instead of images of the real world, in order to remove expectations based on semantic associations with objects and the schematic context of the view. Close-angle and wide-angle scenes were created using irregular geometric shapes rated by independent observers as lacking any easily recognizable structure. The abstract objects were tested on either a random-dot or a blank background in order to assess the influence of implied continuation of the image beyond its boundaries. The random-dot background conditions had background occlusion cues either present or absent at the image border, in order to test their influence on BE in the absence of high-level information about the scenes. The results indicate that high-level information about objects and schematic context is unnecessary for BE to occur, and that occlusion information at the image boundary also has little influence on BE. Contrary to previous studies, we also found clear BE for all conditions, despite using scenes depicting undetailed objects on a blank white background. The results highlighted the ubiquitous nature of BE and the adaptability of scene perception processes.     

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.     

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.     

Does inversion affect boundary extension for briefly-presented views?

Inverting scenes interferes with visual perception and memory on many tasks. Might scene inversion eliminate boundary extension (BE) for briefly-presented photographs? In Experiment 1, an upright or inverted photograph (133, 258, or 383?ms) was followed by a 258 ms masked interval and a test photograph showing the identical view. Test photographs were rated as “same”, “closer”, or “farther away” (5-point scale). BE was just as great for inverted as upright views at the 133 and 383 ms durations, but surprisingly was greater for inverted views at the 258 ms duration. In Experiment 2, 258-ms views yielded greater BE when the study photographs were always tested in the opposite orientation, indicating that the difference in BE was related to encoding. Results suggest that scene construction beyond the view boundaries occurs rapidly and is not impeded by scene inversion, but that changes in the relative quality of visual details available for upright and inverted views may sometimes yield increased BE for inverted scenes.     

Why does vantage point affect boundary extension?

To determine if layout affects boundary extension (BE; false memory beyond view boundaries; Intraub & Richardson, 1989), 12 single-object scenes were photographed from three vantage points: central (0°), shifted rightward (45°), and shifted leftward (45°). Size and position of main objects were held constant. Pictures were presented for 15 s each and were repeated at test with their boundaries: (a) displaced inward or outward (Experiment 1: N=120), or (b) identical to the stimulus views (Experiment 2: N=72). When participants adjusted test boundaries to match memory, BE always occurred, but tended to be smaller for 45° views. We propose this reflects the fact that more of the 3-D scene is visible in the 45° views. This suggests that scene representation reflects the 3-D world conveyed by the global characteristics of layout, rather than the 2-D distance between the main object and the boundaries of a picture.