Piagetian stage IV search errors with an object that is directly accessible both visually and manually

Previous work has shown that infants make the Piagetian stage IV error when the object is covered by a transparent occluder. However, it is not clear whether this happens because nine-month-old infants' failure to understand the identity of hidden objects extends to visible objects, or whether they are puzzled by object relationships involving transparency. Nine-month-old infants were presented with one of three different stage IV tasks in which the object was visible and uncovered at the second location. Stage IV errors were obtained with the object visible, but only when a covered place was provided at the first location. It is concluded that this result is stronger evidence that the stage IV error is not simply a hidden-object phenomenon, and that it may be best explained by taking account of infants' functional place knowledge, as well as their knowledge of object identity.     

Object disappearance and error in Piaget's Stage IV task

Piaget attributes perseverative error in infant manual search to the failure of the infant to conceive of objects as permanent entities which retain their identity when hidden at successive locations A and B. An experiment was performed to test this explanation in which search was compared under three conditions: when the object was hidden at A and B, when the object was covered but visible at A and B, and when the object was visible and uncovered at A and B. Errors occurred under all three conditions taking the form of a conflict in which infants searched persistently either at A or at B. The conflict was at a maximum when the object was hidden, but was evident even when the object was visible but covered. It is suggested that errors may reflect lack of coordination between egocentric and visual frames of reference in relation to which the object is located.     

Perceptual Sensitivity and Motoric Competence in 5- and 6-Month-Old Infants

The authors explored whether 5- to 6-month-old infants were sensitive to perceptual information and how they used perception as a recognition cue to search for a hidden object. In addition, the authors categorized and examined infant grasp by developmental effectiveness to determine any impact on infant search behaviors. In a within-participants design, 20 infants were presented with a toy in 2 occluder conditions. The toy was hidden under either a thick, camouflaging cloth or a thin, semitransparent cloth. The data revealed significant effects of perceptual sensitivity, age, and motor sophistication on search tasks. The results suggest that motor competence might be a limiting factor in infants' abilities to link motoric responses to notions about an object.     

Infants’ coding of location in continuous space

The ability to code location in continuous space is fundamental to spatial behavior. Existing evidence indicates a robust ability for such coding by 12 months, but systematic evidence on earlier origins is lacking. A series of studies investigated 5-month-olds’ ability to code the location of an object hidden in a sandbox, using a looking-time paradigm. In Experiment 1, after familiarization with a hiding-and-finding sequence at one location, infants looked longer at an object being disclosed from a location 12 inches (30 cm) away than at an object emerging from the hiding location, showing they were able to code location in continuous space. In Experiment 2, infants reacted with greater looking when objects emerged from locations 8 inches (20 cm) away from the hiding location, showing that location coding was more finely grained than could be inferred based on the first study. In Experiment 3, infants were familiarized with an object shown in hiding-and-finding sequences at two different locations. Infants looked longer at objects emerging 12 inches (30 cm) away from the most recent hiding location than to emergence from the other location, showing that infants could code location even when events had previously occurred at each location. In Experiment 4, after familiarization with two objects with different shapes, colors, and sounding characteristics, shown in hiding-and-finding sequences in two locations, infants reacted to location violations as they had in Experiment 3. However, they did not react to object violations, that is, events in which the wrong object emerged from a hiding location. Experiment 5 also found no effect of object violation, even when the infants initially saw the two objects side by side. Spatiotemporal characteristics may play a more central role in early object individuation than they do later, although further study is required.     

Going around transparent and grid‐like barriers: detour ability as a perception–action skill

Early detour ability may not generalize immediately across similar problems in different perception–action systems, but instead may reveal a pattern of developmental onset that is more domain‐specific. To investigate this possibility, we examined how 10‐month‐old (n = 24) and 12‐month‐old (n = 24) infants performed detours via different action modes and around barriers that differed in transparency. Infants made reaching and locomotor detours to retrieve an object located behind either an upright transparent barrier or an upright transparent barrier overlaid with a grid pattern. The results indicated that infants were more likely to make reaching than locomotor detours and explored the transparent and grid barriers differently. Additionally, younger infants more often attempted to contact the object through the entirely transparent barrier than did older infants, especially when making a reaching detour. The results suggest that during detour development, infants learn to coordinate relevant perceptual information with emerging actions.     

Infants' reasoning about opaque and transparent occluders in an individuation task

There has been some debate about whether infants 10 months and younger can use featural information to individuate objects. The present research tested the hypothesis that negative results obtained with younger infants reflect limitations in information processing capacities rather than the inability to individuate objects based on featural differences. Infants aged 9.5 months saw one object (i.e. a ball) or two objects (i.e. a box and a ball) emerge successively to opposite sides of an opaque occluder. Infants then saw a single ball either behind a transparent occluder or without an occluder. Only the infants who saw the ball behind the transparent occluder correctly judged that the one-ball display was inconsistent with the box-ball sequence. These results suggest that: (a) infants categorize events involving opaque and transparent occluders as the same kind of physical situation (i.e. occlusion) and (b) support the notion that infants are more likely to give evidence of object individuation when they need to reason about one kind of event (i.e. occlusion) than when they must retrieve and compare categorically distinct events (i.e. occlusion and no-occlusion).     

Infants' search for visible objects: implications for the interpretation of early search errors

This study examined the error patterns of 9-month-old infants searching for hidden objects and objects that were visible within a container. Although errors occurred in both conditions, there were important differences between them. When the object was hidden, infants showed significant perseveration in that they searched more often at the object's previous hiding place than at a control location. When the object was visible, however, they made fewer errors and the errors they did make were as likely to be to the control location as to the previous hiding place. These results suggest that infants' errors in searching for a visible object reflect lapses of attention rather than systematic misunderstandings of objects or space and so are not incompatible with an information-processing account of early search.     

Young infants' perception of unity and form in occlusion displays

Young infants have been reported to perceive the unity of a center-occluded object when the visible ends of the object are aligned and undergo common motion but not when the edges of the object are misaligned (Johnson & Aslin, 1996). Using a recognition-based paradigm, the authors investigated the possibility that past research failed to provide sufficiently sensitive assessments of infants' perception of the unity of misaligned edges in partial occlusion displays. Positive evidence was obtained in 4-month-olds for veridical perception of the motion and location of a hidden region but not its orientation, whereas 7-month-olds, in contrast to the younger infants, appeared to respond to the orientation of the hidden region. Overall, the results suggest that habituation designs tapping recognition processes may be particularly efficacious in revealing infants' perceptual organization. In addition, the findings provide corroborative evidence for the importance of both motion and orientation in young infants' object segregation and for the difficulty in achieving percepts of the global form of a partly occluded object.     

Why do young infants fail to search for hidden objects?

Recent evidence indicates that infants as young as 3.5 months of age understand that objects continue to exist when hidden (Baillargeon, 1987a; Baillargeon & DeVos, 1990). Why, then, do infants fail to search for hidden objects until 7 to 8 months of age? The present experiments tested whether 5.5-month-old infants could distinguish between correct and incorrect search actions performed by an experimenter. In Experiment 1, a toy was placed in front of (possible event) or under (impossible event) a clear cover. Next, a screen was slid in front of the objects, hiding them from view. A hand then reached behind the screen and reappeared holding the toy. The infants looked reliably longer at the impossible than at the possible event, suggesting that they understood that the hand's direct reaching action was sufficient to retrieve the toy when it stood in front of but not under the clear cover. The same results were obtained in a second condition in which a toy was placed in front of (possible event) or behind (impossible event) a barrier. In Experiment 2, a toy was placed under the right (possible event) or the left (impossible event) of two covers. After a screen hid the objects, a hand reached behind the screen's right edge and reappeared first with the right cover and then with the toy. The infants looked reliably longer at the impossible than at the possible event, suggesting that they realized that the hand's sequence of action was sufficient to retrieve the toy when it stood under the right but not the left cover. A control condition supported this interpretation. Together, the results of Experiments 1 and 2 indicate that by 5.5 months of age, infants not only represent hidden objects, but are able to identify the actions necessary to retrieve these objects. The implications of these findings for a problem solving explanation of young infants' failure to retrieve hidden objects are considered.     

Infants' Object Search: Effects of Variable Object Visibility Under Constant Means-End Demands

Why do infants have difficulty searching for objects hidden by occluders before 8 months when other evidence has indicated they are sensitive to hidden objects months earlier? One explanation suggests that infants know hidden objects exist but lack the means-end skill to retrieve them from occluders. However, this experiment explores the unique contribution of object visibility by presenting 6- and 10-month-old infants with visible and hidden objects that could be retrieved with little to no means-end skill. Results indicate that 6-month-old infants searched significantly less for hidden objects than visible objects, although both conditions were equated for means-end demands. In contrast, there were no differences among 10-month-old infants. These results highlight the effect of object visibility on search and indicate that a means-end deficit cannot be the only cause of search problems. Explanations for the effect of object visibility are discussed.     

Search behaviour of cats (Felis catus) in an invisible displacement test: cognition and experience

An invisible displacement test was administered to cats in order to test the hypothesis that search behaviour in this species is influenced by their limited capacity for object permanence as well as by their previous experience with the environment. Experiment 1 compared three groups of cats in a five-choice hiding task in which the hiding places could be discriminated by their spatial positions. Two groups received a visible displacement training before the invisible displacement test and one group did not. Experiment 2 compared two groups of trained subjects in the same task, but the hiding places could be discriminated by spatial and visual cues. The results confirmed that cats are unable to solve problems with invisible displacements. The visible displacement training improved their performance, but was not sufficient to make them succeed. Experience with the hiding potential of the covers also gives more persistence to search behaviour. Finally, the distribution of search attempts is not determined by the proximity to the target and is influenced only partially by the subjects' previous experience. Like Stage 5 infants, cats rely mainly on their immediate perception. They search for an object in the last location they have seen it disappear or under the nearest cover from this location.     

Infants’ understanding of auditory events

Infants’ reaching‐in‐the‐dark was studied in a sample of normal 7.5–11‐month‐olds to determine whether infants can use sound cues to localize and recognize the action and objects of complex events. Infants were shown an event in which a moving, sounding object rotated clockwise through the infant's reaching space in the light and dark. Infrared recorded videotapes were later coded for reaching behaviour. Results showed that infants were able to localize the object on most trials in the dark but were slower and less efficient than in the light. Infants grasped the object at first contact and contacted the object near its salient feature in the dark, suggesting recognition of the object. Further, contact time was 1.7 s less when infants grasped the object at first contact in the dark (recognition) than when they touched the object, suggesting that recognition of the object improves reaching efficiency. There were no age and gender differences. In sum, the results support the use of the reaching‐in‐the‐dark method to demonstrate auditory localization of moving sounds and to reveal infants capacity to use represented information to guide subsequent action. Copyright © 1999 John Wiley & Sons, Ltd.     

To reach or not to reach? Perception of body effectivities by young infants

Two experiments compared 6‐month‐old infants as they reach for an object. All were proficient reachers but with different levels of sitting ability. The object was presented at various distances, within and beyond reach of the infant. In the first experiment, the scaling of perceived reachability in infants with different postural abilities (i.e. non‐sitter, near‐sitter, and sitter infants) was explored. The second experiment investigated the role of proprioception in the scaling of perceived reachability by non‐sitter and sitter infants. In general, results suggest that perceived reachability is calibrated in relation to the degree of postural control achieved by the infant. Infants demonstrate a sense of their own situation in the environment as well as a sense of their own body effectivities. Both determine the execution, or non‐execution, of reaching for a distal object by young infants. Copyright © 1999 John Wiley & Sons, Ltd.     

Infants' intermodal perception of two levels of temporal structure in natural events

Infants' intermodal perception of two levels of temporal structure uniting the visual and acoustic stimulation from natural, complex events was investigated in four experiments. Films depicting a single object (single, large marble) and a compound object (group of smaller marbles) colliding against a surface in an erratic pattern were presented to infants between 3 and months of age using an intermodal preference and search method. These stimulus events portrayed two levels of invariant temporal structure: (a) temporal synchrony united the sights and sounds of object impact, and (b) temporal microstructure, the internal temporal structure of each impact sound and motion, specified the composition of the object (single vs. compound). Experiment 1 demonstrated that by 6 months infants detected a relation between the audible and visible stimulation from these events when both levels of invariant temporal structure guided their intermodal exploration. Experiment 2 revealed that by 6 months infants detected the bimodal temporal microstructure specifying object composition. They looked predominantly to the film whose natural soundtrack was played even though the motions of objects in both films were synchronized with the soundtrack. Experiment 3 assessed infants' sensitivity to temporal synchrony relations. Two films depicting objects of the same composition were presented while the motions of only one of them was synchronized with the appropriate soundtrack. Both 6-month-olds showed evidence of detecting temporal synchrony relations under some conditions. Experiment 4 examined how temporal synchrony and temporal microstructure interact in directing intermodal exploration. The natural soundtrack to one of the objects was played out-of-synchrony with the motions of both. In contrast with the results of Experiment 2, infants at 6 months showed no evidence of detecting a relationship between the film and its appropriate soundtrack. This suggests that the temporal asynchrony disrupted their detection of the temporal microstructure specifying object composition. Results of these studies support on invariant-detection view of the development of intermodal perception.     

Place versus response as the basis of spatial errors made by young infants

Nine-month-old infants search successfully for an object which they have seen hidden in one position, but they frequently continue to search for it there after observing it being hidden in a new position. This error can be explained in terms either of egocentric response perseveration or of perseveration to a particular place in space. In order to distinguish between these hypotheses, 80 infants were presented with a problem consisting of several different conditions which separated response, position on a table, and absolute spatial position as factors leading to errors in search for hidden objects. The results strongly support the egocentric response hypothesis. The reason for this response perseveration strategy is discussed in terms of the lack of active experience of spatial displacements among 9-month-old infants.     

不同母语环境下16个月婴儿词汇表征中声调的语义特性

采用跨通道注视偏好范式(IPLP)下的声调错读任务, 探究16个月中英婴儿熟悉词汇表征中普通话声调的音位语义特性(phonological specificity)。结果发现在先正确命名再声调错读的任务顺序下, 中英婴儿均在正确命名时表现出命名效应, 在错读时不能再认目标图片, 表现出错读效应, 说明普通话声调对16个月中英婴儿而言都具备语义特性。     

Will infants search when ‘no toy’ is hidden? A study of implicit assumptions about the development of object permanence

In the Piagetian tradition, presence or absence of a sense of object permanence is inferred from whether an infant does or does not search when an object is occluded. This line of reasoning entails an implicit assumption, i.e. an infant will not search if no object is seen to disappear. This assumption was evaluated in three studies of 9- and 12-month-old infants' responses to ‘hiding’ toy and ‘no toy’ in different orders in one and two positions. The infants did not search for ‘no toy’ when it preceded toy hiding, but they did search for ‘no toy’ when it followed ‘toy’ under some conditions.     

Serial search and comparison of features of imagined and perceived objects

Four experiments studied the spatial information processing involved in making a series of same-different comparisons of features of two objects. When the path between successively compared features on one object was antiparallel with the corresponding path on the other, comparison of a series of features took longer and produced many more errors. These results were observed both when the objects were externally presented and when one object was imagined and the other externally presented. Knowing the location of the next feature seems much more important for effective search than does monitoring the location of the feature used in the preceding comparison. When paths between corresponding features are parallel, search of features of one object may guide search of the other. When the directions between corresponding features are incongruous, search for the next angle may produce a competition for processes or processing resources, or may produce interfering cross-talk between the spatial information processing of the concurrent search tasks. Because of incongruity, as demonstrated in this study, serial search of objects at different orientations is difficult.     

The development of spatial understanding in infancy

This paper examines the development of spatial understanding between 8 and 24 months. In particular, it examines whether young infants code changes in the position of an object or themselves in geographic or egocentric terms. The infants sat in a baby chair which was attached to a circular table in such a way that either the infant could be rotated around the edge of the table or the table-top itself could be rotated. Rotation of infant or table could be performed independently or simultaneously. Infants were shown an object which was then hidden under one of either two or three identical cups sitting on the table. Before the infant was allowed to search for the toy, either the table, the infant, or both were rotated, a procedure which resulted in an invisible displacement of the object in terms of geographical and/or egocentric spatial position. Rotations of 60, 90, 120, and 180° were used. Three groups of infants were tested, one cross-sectional (12–24 months), one longitudinal (12–24 months), and one consisting of a group of infants already known to be accelerated in object concept development (8–20 months). The cross-sectional results indicated that egocentric responding continues well into the second half of the second year of life. Even with fortnightly exposure to the tasks, egocentric responding was still evident in some longitudinal babies as late as 19 months. The results of the accelerated group suggest that acceleration through the sequence of object concept development facilitates development of spatial understanding in a wider sense, that is, in the sense of understanding the interrelation of positions in space. The implications of these results for competing theories of the source of object concept errors are discussed.     

Infants' perception of concavity and convexity of shaded objects

The discriminative sensitivities of 30 4‐month‐old and 30 8‐month‐old infants for concave and convex objects were measured using the preferential‐looking method. Five cylinder‐like objects with different magnitudes of concave or convex shaded surfaces and outline contours were presented to the infants in pairs. The results indicated that the 4‐month‐old infants could discriminate better between object convexities than between object concavities. In contrast, the 8‐month‐old infants were able to equally discriminate between object concavities and object convexities, and their sensitivity to both object concavity/convexity was much higher than that of the 4‐month‐old infants. This difference in the sensitivity to object concavity and convexity suggested that younger and older infants might have differential abilities for cue utilization for recovering object structures.