Scene consistency in object and background perception

Does knowledge about which objects and settings tend to co-occur affect how people interpret an image? The effects of consistency on perception were investigated using manipulated photographs containing a foreground object that was either semantically consistent or inconsistent with its setting. In four experiments, participants reported the foreground object, the setting, or both after seeing each picture for 80 ms followed by a mask. In Experiment 1, objects were identified more accurately in a consistent than an inconsistent setting. In Experiment 2, backgrounds were identified more accurately when they contained a consistent rather than an inconsistent foreground object. In Experiment 3, objects were presented without backgrounds and backgrounds without objects; comparison with the other experiments indicated that objects were identified better in isolation than when presented with a background, but there was no difference in accuracy for backgrounds whether they appeared with a foreground object or not. Finally, in Experiment 4, consistency effects remained when both objects and backgrounds were reported. Semantic consistency information is available when a scene is glimpsed briefly and affects both object and background perception. Objects and their settings are processed interactively and not in isolation.     

Identification of objects in scenes: the role of scene background in object naming.

Research with brief presentations of scenes has indicated that scene context facilitates object identification. In the present experiments we used a paradigm in which an object in a scene is "wiggled"--drawing both attention and an eye fixation to itself--and then named. Thus the effect of scene context on object identification can be examined in a situation in which the target object is fixated and hence is fully visible. Experiment 1 indicated that a scene background that was episodically consistent with a target object facilitated the speed of naming. In Experiments 2 and 3, we investigated the time course of scene background information acquisition using display changes contingent on eye movements to the target object. The results from Experiment 2 were inconclusive; however, Experiment 3 demonstrated that scene background information present only on either the first or second fixation on a scene significantly affected naming time. Thus background information appears to be both extracted and able to affect object identification continuously during scene viewing.     

Selective attention during scene perception: Evidence from negative priming

In two experiments, we examined the role of semantic scene content in guiding attention during scene viewing. In each experiment, performance on a lexical decision task was measured following the brief presentation of a scene. The lexical decision stimulus named an object that was either present or not present in the scene. The results of Experiment 1 revealed no priming from inconsistent objects (whose identities conflicted with the scene in which they appeared), but negative priming from consistent objects. The results of Experiment 2 indicated that negative priming from consistent objects occurs only when inconsistent objects are present in the scenes. Together, the results suggest that observers are likely to attend to inconsistent objects, and that representations of consistent objects are suppressed in the presence of an inconsistent object. Furthermore, the data suggest that inconsistent objects draw attention because they are relatively difficult to identify in an inappropriate context.     

Consistency effects between objects in scenes

How does context influence the perception of objects in scenes? Objects appear in a given setting with surrounding objects. Do objects in scenes exert contextual influences on each other? Do these influences interact with background consistency? In three experiments, we investigated the role of object-to-object context on object and scene perception. Objects (Experiments 1 and 3) and backgrounds (Experiment 2) were reported more accurately when the objects and their settings were consistent than when they were inconsistent, regardless of the number of foreground objects. In Experiment 3, related objects (from the same setting) were reported more accurately than were unrelated objects (from different settings), independently of consistency with the background. Consistent with an interactive model of scene processing, both object-to-object context and object-background context affect object perception.     

The influence of color on the perception of scene gist

In 3 experiments the authors used a new contextual bias paradigm to explore how quickly information is extracted from a scene to activate gist, whether color contributes to this activation, and how color contributes, if it does. Participants were shown a brief presentation of a scene followed by the name of a target object. The target object could be consistent or inconsistent with scene gist but was never actually present in the scene. Scene gist activation was operationalized as the degree to which participants respond "yes" to consistent versus inconsistent objects, reflecting a response bias produced by scene gist. Experiment 1 demonstrated that scene gist is activated after a 42-ms exposure and that the strength of the activation increases with longer presentation durations. Experiments 2 and 3 explored the contribution of color to the activation of scene gist. The results revealed that color has an influence across a wide variety of scenes and is directly associated with scene gist.     

Effects of foveal priming and extrafoveal preview on object identification

The results of three different experiments suggested that the relation between an object in the fovea on fixation n and an object subsequently brought into the fovea on fixation n + 1 affects the time to identify the second object. In Experiment 1 we extended previous work by demonstrating that a previously seen related priming object speeded the time to name a target object even when a saccade intervened between the two objects. In Experiment 2 we replicated this result and further showed that the benefit on naming time was due to facilitation from the related object rather than inhibition from the unrelated object. In addition, naming of the target object was much slower in both experiments when there was not a peripheral preview of the target object on fixation n. However, because the effect of the foveal priming object was greater when the target was not present than when it was present, priming did not appear to make extraction of the extrafoveal information more efficient. In Experiment 3, fixation times were recorded while subjects looked at four objects in order to identify them. Fixation time on an object was shorter when a related object was fixated immediately before it, even though the four objects did not form a scene. The size of the facilitation was roughly comparable to that in several analogous experiments where scenes were used. The results suggest that the effects of a predictive scene context on object identification may be explainable in terms of an object-to-object or "intralevel" priming mechanism.     

Stuck on semantics: Processing of irrelevant object-scene inconsistencies modulates ongoing gaze behavior

People have an amazing ability to identify objects and scenes with only a glimpse. How automatic is this scene and object identification? Are scene and object semantics—let alone their semantic congruity—processed to a degree that modulates ongoing gaze behavior even if they are irrelevant to the task at hand? Objects that do not fit the semantics of the scene (e.g., a toothbrush in an office) are typically fixated longer and more often than objects that are congruent with the scene context. In this study, we overlaid a letter T onto photographs of indoor scenes and instructed participants to search for it. Some of these background images contained scene-incongruent objects. Despite their lack of relevance to the search, we found that participants spent more time in total looking at semantically incongruent compared to congruent objects in the same position of the scene. Subsequent tests of explicit and implicit memory showed that participants did not remember many of the inconsistent objects and no more of the consistent objects. We argue that when we view natural environments, scene and object relationships are processed obligatorily, such that irrelevant semantic mismatches between scene and object identity can modulate ongoing eye-movement behavior.     

Semantic Informativeness Mediates the Detection of Changes in Natural Scenes

Three experiments investigated whether the semantic informativeness of a scene region (object) influences its representation between successive views. In Experiment 1, a scene and a modified version of that scene were presented in alternation, separated by a brief retention interval. A changed object was either semantically consistent with the scene (non-informative) or inconsistent (informative). Change detection latency was shorter in the semantically inconsistent versus consistent condition. In Experiment 2, eye movements were eliminated by presenting a single cycle of the change sequence. Detection accuracy was higher for inconsistent versus consistent objects. This inconsistent object advantage was obtained when the potential strategy of selectively encoding inconsistent objects was no longer advantageous (Experiment 3). These results indicate that the semantic properties of an object influence whether the representation of that object is maintained between views of a scene, and this influence is not caused solely by the differential allocation of eye fixations to the changing region. The potential cognitive mechanisms supporting this effect are discussed.     

Testing a conceptual locus

Changes to objects that are inconsistent with the scene in which they appear are detected more accurately than changes to consistent objects. In three experiments, we tested whether this inconsistent object advantage derives from the differential retention of conceptual codes generated from a brief view of a real-world scene in accordance with a conceptual short-term memory (CSTM) hypothesis. A scene was presented for 250 msec, followed by a brief mask and a test scene in which a target object was either changed or not changed. In Experiment 1, changes that altered conceptual content (object deletion) were contrasted with visual changes (left-right orientation changes). In Experiment 2, the duration of the mask was manipulated to vary the amount of time available for conceptual consolidation of the initial scene. In Experiment 3, the type of mask was manipulated: Either a meaningless pattern mask or a meaningful, and thus conceptually disruptive, scene was shown. The inconsistent object advantage was obtained in each experiment, yet in none was it modulated in the direction predicted by the CSTM hypothesis. Instead, the inconsistent object advantage is likely to be caused by contextual influence on memory for visual object representations.     

Detection and Identification of Change in Naturalistic Scenes

Research using change detection paradigms has demonstrated that only limited scene information remains available for conscious report following initial inspection of a scene. Previous researchers have found higher change identification rates for deletions of parts of objects in line drawings of scenes than additions. Other researchers, however, have found an asymmetry in the opposite direction for addition/deletion of whole objects in line drawings of scenes. Experiment 1 investigated subjects' accuracy in detecting and identifying changes made to successive views of high quality photographs of naturalistic scenes that involved the addition and deletion of objects, colour changes to objects, and changes to the spatial location of objects. Identification accuracy for deletions from scenes was highest, with lower identification rates for object additions and colour changes, and the lowest rates for identification of location changes. Data further suggested that change identification rates for the presence/absence of objects were a function of the number of identical items present in the scene. Experiment 2 examined this possibility further, and also investigated whether the higher identification rates for deletions found in Experiment 1 were found for changes involving whole objects or parts of objects. Results showed higher identification rates for deletions, but only where a unique object was deleted from a scene. The presence of an identical object in the scene abolished this deletion identification advantage. Results further showed that the deletion/addition asymmetry occurs both when the objects are parts of a larger object and when they are entire objects in the scene.     

Scene and position specificity in visual memory for objects

This study investigated whether and how visual representations of individual objects are bound in memory to scene context. Participants viewed a series of naturalistic scenes, and memory for the visual form of a target object in each scene was examined in a 2-alternative forced-choice test, with the distractor object either a different object token or the target object rotated in depth. In Experiments 1 and 2, object memory performance was more accurate when the test object alternatives were displayed within the original scene than when they were displayed in isolation, demonstrating object-to-scene binding. Experiment 3 tested the hypothesis that episodic scene representations are formed through the binding of object representations to scene locations. Consistent with this hypothesis, memory performance was more accurate when the test alternatives were displayed within the scene at the same position originally occupied by the target than when they were displayed at a different position.     

Scene perception: Detecting and judging objects undergoing relational violations

Five classes of relations between an object and its setting can characterize the organization of objects into real-world scenes. The relations are (1) Interposition (objects interrupt their background), (2) Support (objects tend to rest on surfaces), (3) Probability (objects tend to be found in some scenes but not others), (4) Position (given an object is probable in a scene, it often is found in some positions and not others), and (5) familiar Size (objects have a limited set of size relations with other objects). In two experiments subjects viewed brief (150 msec) presentations of slides of scenes in which an object in a cued location in the scene was either in a normal relation to its background or violated from one to three of the relations. Such objects appear to (1) have the background pass through them, (2) float in air, (3) be unlikely in that particular scene, (4) be in an inappropriate position, and (5) be too large or too small relative to the other objects in the scene. In Experiment I, subjects attempted to determine whether the cued object corresponded to a target object which had been specified in advance by name. With the exception of the Interposition violation, violation costs were incurred in that the detection of objects undergoing violations was less accurate and slower than when those same objects were in normal relations to their setting. However, the detection of objects in normal relations to their setting (innocent bystanders) was unaffected by the presence of another object undergoing a violation in that same setting. This indicates that the violation costs were incurred not because of an unsuccessful elicitation of a frame or schema for the scene but because properly formed frames interfered with (or did not facilitate) the perceptibility of objects undergoing violations. As the number of violations increased, target detectability generally decreased. Thus, the relations were accessed from the results of a single fixation and were available sufficiently early during the time course of scene perception to affect the perception of the objects in the scene. Contrary to expectations from a bottom-up account of scene perception, violations of the pervasive physical relations of Support and Interposition were not more disruptive on object detection than the semantic violations of Probability, Position and Size. These are termed semantic because they require access to the referential meaning of the object. In Experiment II, subjects attempted to detect the presence of the violations themselves. Violations of the semantic relations were detected more accurately than violations of Interposition and at least as accurately as violations of Support. As the number of violations increased, the detectability of the incongruities between an object and its setting increased. These results provide converging evidence that semantic relations can be accessed from the results of a single fixation. In both experiments information about Position was accessed at least as quickly as information on Probability. Thus in Experiment I, the interference that resulted from placing a fire hydrant in a kitchen was not greater than the interference from placing it on top of a mail ? in a street scene. Similarly, violations of Probability in Experiment II were not more detectable than violations of Position. Thus, the semantic relations which were accessed included information about the detailed interactions among the objects—information which is more specific than what can be inferred from the general setting. Access to the semantic relations among the entities in a scene is not deferred until the completion of spatial and depth processing and object identification. Instead, an object's semantic relations are accessed simultaneously with its physical relations as well as with its own identification.     

Local and global contextual constraints on the identification of objects in scenes.

Objects likely to appear in a given real-world scene are frequently found to be easier to recognize. Two different sources of contextual information have been proposed as the basis for this effect: global scene background and individual companion objects. The present paper examines the relative importance of these two elements in explaining the context-sensitivity of object identification in full scenes. Specific sequences of object fixations were elicited during free scene exploration, while fixation times on designated target objects were recorded as a measure of ease of target identification. Episodic consistency between the target, the global scene background, and the object fixated just prior to the target (the prime), were manipulated orthogonally. Target fixation times were examined for effects of prime and background. Analyses show effects of both factors, which are modulated by the chronology and spatial extent of scene exploration. The results are discussed in terms of their implications for a model of visual object recognition in the context of real-world scenes.     

The role of context on boundary extension

Boundary extension (BE) is a memory error in which observers remember more of a scene than they actually viewed. This error reflects one’s prediction that a scene naturally continues and is driven by scene schema and contextual knowledge. In two separate experiments we investigated the necessity of context and scene schema in BE. In Experiment 1, observers viewed scenes that either contained semantically consistent or inconsistent objects as well as objects on white backgrounds. In both types of scenes and in the no-background condition there was a BE effect; critically, semantic inconsistency in scenes reduced the magnitude of BE. In Experiment 2 when we used abstract shapes instead of meaningful objects, there was no BE effect. We suggest that although scene schema is necessary to elicit BE, contextual consistency is not required.     

To see and remember: visually specific information is retained in memory from previously attended objects in natural scenes

What is the nature of the representation formed during the viewing of natural scenes? We tested two competing hypotheses regarding the accumulation of visual information during scene viewing. The first holds that coherent visual representations disintegrate as soon as attention is withdrawn from an object and thus that the visual representation of a scene is exceedingly impoverished. The second holds that visual representations do not necessarily decay upon the withdrawal of attention, but instead can be accumulated in memory from previously attended regions. Target objects in line drawings of natural scenes were changed during a saccadic eye movement away from those objects. Three findings support the second hypothesis. First, changes to the visual form of target objects (token substitution) were successfully detected, as indicated by both explicit and implicit measures, even though the target object was not attended when the change occurred. Second, these detections were often delayed until well after the change. Third, changes to semantically inconsistent target objects were detected better than changes to semantically consistent objects.     

靶刺激变换与情景信息属性对真实情景再认的影响

采用眼动研究范式,通过两个实验考察靶刺激变换与情景信息属性对情景再认的影响。实验一结果显示,靶刺激变换对情景再认、靶刺激所属兴趣区的凝视时间均有显著影响,这表明在情景再认过程中,观察者会有意识地搜索靶刺激,靶刺激具有诊断效应;实验二应用了知觉信息与语义信息重合和分离两种情景材料。结果显示,观察者对语义信息的首次注视次数显著多于知觉信息;观察者对知觉信息和语义信息分离条件下语义信息的首次注视时间显著长于重合条件下。这一结果提示,在情景识别过程中,语义信息具有注意优先性,但其优先性会受到知觉信息启动的干扰。     

Attentional allocation during the perception of scenes

Semantic influences on attention during the 1st fixation on a scene were explored in 3 experiments. Subjects viewed briefly presented scenes; following scene presentation, a spatial probe was presented at the location of an object whose identity was consistent or inconsistent with the scene category. Responses to the probe served as an index of attention. The results of Experiment 1 suggest that within approximately 150 ms of scene onset, subjects attend preferentially to inconsistent objects. The results of Experiment 2, in which additional scene durations were used, confirm the presence of an inconsistent-object advantage that emerges within approximately 150 ms. Finally, the results of Experiment 3 demonstrate that the inconsistent-object advantage does not reflect strategic allocation of attention to likely probe locations. Implications of the results for scene perception and exploration are discussed.     

Saccade latency reveals episodic representation of object color

While previous studies suggest that identity, but not color, plays a role in episodic object representation, such studies have typically used tasks in which only identity is relevant, raising the possibility that the results reflect task demands, rather than the general principles that underlie object representation. In the present study, participants viewed a preview display containing one (Experiments 1 and 2) or two (Experiment 3) letters, then viewed a target display containing a single letter, in either the same or a different location. Participants executed an immediate saccade to fixate the target; saccade latency served as the dependent variable. In all experiments, saccade latencies were longer to fixate a target appearing in its previewed location, consistent with a bias to attend to new objects rather than to objects for which episodic representations are being maintained in visual working memory. The results of Experiment 3 further demonstrate, however, that changing target color eliminates these latency differences. The results suggest that color and identity are part of episodic representation even when not task relevant and that examining biases in saccade execution may be a useful approach to studying episodic representation.