Structural similarity and spatiotemporal noise effects on learning dynamic novel objects

The spatiotemporal pattern projected by a moving object is specific to that object, as it depends on both the shape and the dynamics of the object. Previous research has shown that observers learn to make use of this spatiotemporal signature to recognize dynamic faces and objects. In two experiments, we assessed the extent to which the structural similarity of the objects and the presence of spatiotemporal noise affect how these signatures are learned and subsequently used in recognition. Observers first learned to identify novel, structurally distinctive or structurally similar objects that rotated with a particular motion. At test, each learned object moved with its studied motion or with a non-studied motion. In the non-studied motion condition we manipulated either dynamic information alone (experiment 1) or both static and dynamic information (experiment 2). Across both experiments we found that changing the learned motion of an object impaired recognition performance when 3-D shape was similar or when the visual input was noisy during learning. These results are consistent with the hypothesis that observers use learned spatiotemporal signatures and that such information becomes progressively more important as shape information becomes less reliable.     

How 7-month-olds interpret ambiguous motion events: Category-based reasoning in infancy

This paper investigates the role of static and dynamic attributes for the animate-inanimate distinction in category-based reasoning of 7-month-olds. Three experiments tested infants’ responses to movement events involving an unfamiliar animal and a ball. When either the animal or the ball showed self-initiated irregular movements (Experiment 1), infants expected the previously active object to start moving again. When both objects were moving together in an ambiguous motion event (Experiment 2), infants expected only the animal to start moving again. Initial looking preferences for each object did not influence results. When either the facial features of the animal were removed, or its furry body was replaced by a plastic spiral in an ambiguous motion event (Experiment 3), infants formed no clear expectation regarding future movements. Based on this set of findings we conclude that 7-month-olds flexibly combine information about the static and dynamic properties of objects in order to reason about motion events.     

Object individuation and event mapping: developmental changes in infants’ use of featural information

The present research examined the development of 4.5‐ to 7.5‐month‐old infants’ ability to map different‐features occlusion events using a simplified event‐mapping task. In this task, infants saw a different‐features (i.e. egg‐column) event followed by a display containing either one object or two objects. Experiments 1 and 2 assessed infants’ ability to judge whether the egg‐column event was consistent with a subsequent one‐column display. Experiments 3 and 4 examined infants’ ability to judge whether the objects seen in the egg‐column event and those seen in a subsequent display were consistent in their featural composition. At 7.5 and 5.5 months, but not at 4.5 months, the infants successfully mapped the egg‐column event onto the one‐column display. However, the 7.5‐ and 5.5‐month‐olds differed in whether they mapped the featural properties of those objects. Whereas the 7.5‐month‐olds responded as if they expected to see two specific objects, an egg and a column, in the final display the 5.5‐month‐olds responded as if they simply expected to see ‘two objects’. Additional results revealed, however, that when spatiotemporal information specified the presence of two objects, 5.5‐month‐olds succeeded at tagging the objects as being featurally distinct, although they still failed to attach more specific information about what those differences were. Reasons for why the younger infants had difficulty integrating featural information into their object representations were discussed.     

Object individuation and object identity in infancy: the role of spatiotemporal information, object property information, and language.

Recent work on object individuation and object identity in infancy indicates that at least three sources of information may be used for object individuation and object identity: spatiotemporal information, object property information, and object kind information. Several experiments have shown that a major developmental change occurs between 10 and 12 months of age (Xu & Carey, 1996; Xu, Carey & Welch, in press; Van de Walle, Prevor & Carey, under review; Xu, Carey & Quint, in preparation): Infants at 10 months and younger readily use spatiotemporal information in object individuation and object identity tasks, but not until about 12 months of age are infants able to use object property or object kind information to do so. This paper proposes a two-part conjecture about the mechanism underlying this change. The first part borrows ideas from object-based attention and the distinction between "what" and "where" information in visual processing. The hypothesis is that (1) young infants encode object motion and location information separately from object property information; and (2) toward the end of the first year, infants integrate these two sources of information. The second part of the conjecture posits an important role for language. Infants may take distinct labels as referring to distinct kinds of objects from the onset of word learning, and infants use this information in solving the problem of object individuation and object identity. Evidence from human adults, infants, and non-human primates is reviewed to provide support for the conjecture.     

That’s the way the ball bounces: infants’ and adults’ perception of spatial and temporal contiguity in collisions involving bouncing balls

Three experiments investigated the perception of collisions involving bouncing balls by 7- and 10-month-old infants and adults. In previous research, 10-month-old infants perceived the causality of launching collisions (events in which one object moves along a smooth horizontal trajectory toward a second object, apparently launching it into motion) in relatively simple event contexts. In more complex event contexts, infants failed to discriminate among the events or respond to changes in individual features. Experiments 1 and 2 of the present investigation revealed that 7- and 10-month-old infants attended to spatial and temporal contiguity, but not causality, in collisions involving the movement of bouncing balls. In Experiment 3, both spatiotemporal contiguity and general knowledge about movement trajectories influenced adults’ judgments of causality for these collisions. The present results add to a growing understanding of infants’ event perception as constructive and a function, in part, of the complexity of the event context.     

Motion and edge sensitivity in perception of object unity

Although much evidence indicates that young infants perceive unitary objects by analyzing patterns of motion, infants' abilities to perceive object unity by analyzing Gestalt properties and by integrating distinct views of an object over time are in dispute. To address these controversies, four experiments investigated adults' and infants' perception of the unity of a center-occluded, moving rod with misaligned visible edges. Both alignment information and depth information affected adults' and infants' perception of object unity in similar ways, and infants perceived object unity by integrating information about object features over time. However, infants perceived a moving, misaligned, three-dimensional object as indeterminate in its connectedness, whereas adults perceived it as connected behind the occluder. These findings indicate that the effectiveness of common motion in specifying unified surfaces across an occluder is reduced by misalignment of edges. Alignment information enhances perception of object unity either by serving directly as information for unity or by optimizing the detectability of motion-carried information for unity. In addition, young infants are able to retain information about edge orientation over short intervals in determining connectedness via a process of spatiotemporal integration.     

Are objects required for object-files? Roles of segmentation and spatiotemporal continuity in computing object persistence

Two central tasks of visual processing are (1) to segment undifferentiated retinal images into discrete objects, and (2) to represent those objects as the same persisting individuals over time and motion. Here we explore the interaction of these two types of processing in the context of object files—mid-level visual representations that “stick” to moving objects on the basis of spatiotemporal properties. Object files can be revealed by object-specific preview benefits (OSPBs), wherein a “preview” of information on a moving object speeds the recognition of that information at a later point when it appears again on the same object (compared to when it reappears on a different moving object), beyond display-wide priming. Here we explore the degree of segmentation required to establish object files in the first place. Surprisingly, we find that no explicit segmentation is required until after the previews disappear, when using purely motion-defined objects (consisting of random elements on a random background). Moreover, OSPBs are observed in such displays even after moderate (but not long) delays between the offset of the preview information and the onset of the motion. These effects indicate that object files can be established without initial static segmentation cues, so long as there is spatiotemporal continuity between the previews and the eventual appearance of the objects. We also find that top-down strategies can sometimes mimic OSPBs, but that these strategies can be eliminated by novel manipulations. We discuss how these results alter our understanding of the nature of object files, and also why researchers must take care to distinguish “true OSPBs” from “illusory OSPBs”.     

Occluded motion alters event perception

We employed audiovisual stream/bounce displays, in which two moving objects with crossing trajectories are more likely to be perceived as bouncing off, rather than streaming through, each other when a brief sound is presented at the coincidence of the two objects. However, Kawachi and Gyoba (Perception 35:1289–1294, 2006b) reported that the presence of an additional moving object near the two objects altered the perception of a bouncing event to that of a streaming event. In this study, we extended this finding and examined whether alteration of the event perception could be induced by the visual context, such as by occluded object motion near the stream/bounce display. The results demonstrated that even when the sound was presented, the continuous occluded motion strongly biased observers’ percepts toward the streaming percept during a short occlusion interval (approximately 100 ms). In contrast, when the continuous occluded motion was disrupted by introducing a spatiotemporal gap in the motion trajectory or by removing occlusion cues such as deletion/accretion, the bias toward the streaming percept declined. Thus, we suggest that a representation of object motion generated under a limited occlusion interval interferes with audiovisual event perception.     

Infants' categorization of novel objects with more or less obvious features

In five experiments, 14- to 15-month-old infants' categorization of objects on the basis of more or less obvious features was investigated. Using an object examining paradigm, a total of 200 infants were familiarized with novel objects that shared either more obvious features (i.e., easily visible) or less obvious features (i.e., accessible by lifting a flap), followed by an in-category object and an out-of-category object. When only perceptual information was available, infants formed a category on the basis of the more obvious features but not on the basis of the less obvious features (Experiments 1 and 3). When infants were provided with animacy cues and/or object names, they formed categories on the basis of either more or less obvious features (Experiments 2, 4, and 5). The results of these studies delineate the role of animacy cues and object names in establishing categories on the basis of less obvious features.     

The power of causal beliefs and conflicting evidence on causal judgments and decision making

In two experiments, we investigated the relative impact of causal beliefs and empirical evidence on both decision making and causal judgments, and whether this relative impact could be altered by previous experience. Participants had to decide which of two alternatives would attain a higher outcome on the basis of four cues. After completing the decision task, they were asked to estimate to what extent each cue was a reliable cause of the outcome. Participants were provided with instructions that causally related two of the cues to the outcome, whereas they received neutral information about the other two cues. Two of the four cues—a causal and a neutral cue—had high validity and were both generative. The remaining two cues had low validity, and were generative in Experiment 1, but almost not related to the outcome in Experiment 2. Selected groups of participants in both experiments received pre-training with either causal or neutral cues, or no pre-training was provided. Results revealed that the impact of causal beliefs and empirical evidence depends on both the experienced pre-training and cue validity. When all cues were generative and participants received pre-training with causal cues, they mostly relied on their causal beliefs, whereas they relied on empirical evidence when they received pre-training with neutral cues. In contrast, when some of the cues were almost not related to the outcome, participants’ responses were primarily influenced by validity and—to a lesser extent—by causal beliefs. In either case, however, the influence of causal beliefs was higher in causal judgments than in decision making. While current theoretical approaches in causal learning focus either on the effect of causal beliefs or empirical evidence, the present research shows that both factors are required to explain the flexibility involved in human inferences.     

The effect of object and event orientation on perception of biological motion

Detection and recognition of point-light walking is reduced when the display is inverted, or turned upside down. This indicates that past experience influences biological motion perception. The effect could be the result of either presenting the human form in a novel orientation or presenting the event of walking in a novel orientation, as the two are confounded in the case of walking on feet. This study teased apart the effects of object and event orientation by examining detection accuracy for upright and inverted displays of a point-light figure walking on his hands. Detection of this walker was greater in the upright display, which had a familiar event orientation and an unfamiliar object orientation, than in the inverted display, which had a familiar object orientation and an unfamiliar event orientation. This finding supports accounts of event perception and recognition that are based on spatiotemporal patterns of motion associated with the dynamics of an event.     

Comment on Hofsten and Spelke, object perception and object-directed reaching in infancy

Hofsten and Spelke (1985) reported a series of studies that quite clearly demonstrated infant sensitivity to depth and relative motion cues. They suggest a salience hierarchy for those cues in which relative motion takes precedence over depth when both cues are present. Based on reports that infants reach for and grasp boundaries in the visual display, the authors make the further claim that these data argue for object perception infants by the time they are 5 months old. The present article argues against this claim on two grounds: First, the authors do not report that infants specifically reached and grasped at boundaries in the display. Second, although patterns of reach are clearly affected by changes in boundary cues, there is no evidence that the boundaries the infants perceive are necessarily object boundaries.     

两种时空线索条件下表面颜色特征线索对客体保持的作用*

采用客体回溯范式,以客体预览利化效应(object specific previewing benefit, OSPB)作为指标,考察表面特征线索对客体保持的作用。实验1使用双向隧道创建时空线索不明确的条件,研究表面颜色特征线索的作用。实验2使用单向隧道使时空线索明确,研究表面颜色特征线索与时空线索一致、冲突情境下的客体保持。实验1和实验2均出现了OSPB效应,且实验2冲突情境的OSPB效应低于一致情境。研究结果表明在时空线索不明确的条件下,仅凭表面颜色特征线索就能实现客体保持;在时空线索明确的条件下,时空线索是客体保持的主要线索,同时表面颜色特征线索也起一定的作用。     

The cradle of causal reasoning: newborns’ preference for physical causality

Perception of mechanical (i.e. physical) causality, in terms of a cause–effect relationship between two motion events, appears to be a powerful mechanism in our daily experience. In spite of a growing interest in the earliest causal representations, the role of experience in the origin of this sensitivity is still a matter of dispute. Here, we asked the question about the innate origin of causal perception, never tested before at birth. Three experiments were carried out to investigate sensitivity at birth to some visual spatiotemporal cues present in a launching event. Newborn babies, only a few hours old, showed that they significantly preferred a physical causality event (i.e. Michotte's Launching effect) when matched to a delay event (i.e. a delayed launching; Experiment 1) or to a non‐causal event completely identical to the causal one except for the order of the displacements of the two objects involved which was swapped temporally (Experiment 3). This preference for the launching event, moreover, also depended on the continuity of the trajectory between the objects involved in the event (Experiment 2). These results support the hypothesis that the human system possesses an early available, possibly innate basic mechanism to compute causality, such a mechanism being sensitive to the additive effect of certain well‐defined spatiotemporal cues present in the causal event independently of any prior visual experience.     

Attunement and Affordance Learning in Infants

ABSTRACT

From a perceptual learning perspective, infants use social information (like gaze direction) in a similar way as other information in our physical environment (like object movements) to specify action possibilities. In the current study, we assumed that infants are able to learn an affordance upon observing an adult failing to act out that affordance, without appreciating object-directed intentions, or, communicative intent towards the infant. Using a variation of the Re-enactment procedure, we found that when the attention of infants (N = 46, M_age = 20 months) was drawn towards the eyes of the person before she acted out the failed attempt, either by ostensive cues or non-ostensive cues, infants achieved more affordances than when their attention was not directed towards the eyes. As directing the attention of infants to the eyes of another person frequently results in gaze following, this suggests that infants use the gaze direction of another person in order to learn what affordance that other person is trying to realize. In addition, the results of a spatiotemporal analysis on the eye-movements of infants suggest that the gaze and the object movements of the person facilitate learning by directing the attention of infants towards important object-directed actions on crucial moments during the failed attempt demonstrations. These results are discussed in terms of perceptual attunement and affordance learning.     

Infants recognize similar goals across dissimilar actions involving object manipulation

We investigated infants’ ability to recognize the similarity between observed and implied goals when actions differed in surface-level motion details. In two experiments, 10- to 12-month-olds were habituated to an actor manipulating an object and then shown test actions in which the actor contacted the object with a novel hand configuration that implied a goal either similar or dissimilar to the habituation event. Infants in both experiments looked significantly longer at test actions depicting a novel implied goal, suggesting that infants glossed over some surface-level motion details and compared implied goals.     

Infants discriminate manners and paths in non-linguistic dynamic events

Do 14- to 17-month-olds notice the paths and manners of motion events? English- and Spanish-learning infants were habituated to an animated motion event including a manner (e.g., spinning) and a path (e.g., over). They were then tested on four types of events that changed either the manner, the path, both, or neither component. Both English- and Spanish-learning infants attended to changes of manner and changes of path. Thus, infants from two different language communities proved sensitive to components of events that undergird relational term learning.     

Will any doll do? 12-month-olds' reasoning about goal objects

Infants as young as 5 months of age view familiar actions such as reaching as goal-directed (Woodward, 1998), but how do they construe the goal of an actor's reach? Six experiments investigated whether 12-month-old infants represent reaching actions as directed to a particular individual object, to a narrowly defined object category (e.g., an orange dump truck), or to a more broadly defined object category (e.g., any truck, vehicle, artifact, or inanimate object). The experiments provide evidence that infants are predisposed to represent reaching actions as directed to categories of objects at least as broad as the basic level, both when the objects represent artifacts (trucks) and when they represent people (dolls). Infants do not use either narrower category information or spatiotemporal information to specify goal objects. Because spatiotemporal information is central to infants' representations of inanimate object motions and interactions, the findings are discussed in relation to the development of object knowledge and action representations.     

Synchronous change and perception of object unity: evidence from adults and infants.

Adults and infants display a robust ability to perceive the unity of a center-occluded object when the visible ends of the object undergo common motion (e.g. Kellman, P.J., Spelke, E.S., 1983. Perception of partly occluded objects in infancy. Cognitive Psychology 15, 483-524). Ecologically oriented accounts of this ability focus on the primary of motion in the perception of segregated objects, but Gestalt theory suggests a broader possibility: observers may perceive object unity by detecting patterns of synchronous change, of which common motion is a special case. We investigated this possibility with observations of adults and 4-month-old infants. Participants viewed a center-occluded object whose visible surfaces were either misaligned or aligned, stationary or moving, and unchanging or synchronously changing in color or brightness in various temporal patterns (e.g. flashing). Both alignment and common motion contributed to adults' perception of object unity, but synchronous color changes did not. For infants, motion was an important determinant of object unity, but other synchronous changes and edge alignment were not. When a stationary object with aligned edges underwent synchronous changes in color or brightness, infants showed high levels of attention to the object, but their perception of its unity appeared to be indeterminate. An inherent preference for fast over slow flash rates, and a novelty preference elicited by a change in rate, both indicated that infants detected the synchronous changes, although they failed to use them as information for object unity. These findings favor ecologically oriented accounts of object perception in which surface motion plays a privileged role.     

Tracking and anticipation of invisible spatial transformations by 4- to 8-month-old infants

The ability of 4- to 8-month-old infants to track and anticipate the final orientation of an object following different invisible spatial transformations was tested. A violation-of-expectation method was used to assess infants' reaction to possible and impossible outcomes of an object's orientation after it translated or rotated behind an occluder. Results of a first experiment show that at all ages infants tend to look significantly longer at an impossible orientation outcome following invisible transformations. These results suggest that from 4 months of age, infants have the ability to detect orientation-specific information about an object undergoing linear or curvilinear invisible spatial transformations. A second experiment controlling for perceptual cues that infants might have used in the first experiment to track the object orientation replicates the results with a new sample of 4- and 6-month-old infants. Finally, a control experiment involving no motion yielded negative results, providing further support that infants as young as 4 months old use motion information to mentally track invisible spatial transformations. The results obtained in the rotation condition of both experiments are tentatively interpreted as providing first evidence of some rudiments of mental rotation in infancy.