The effect of a looker’s past reliability on infants’ reasoning about beliefs.

We investigated whether 16-month-old infants’ past experience with a person’s gaze reliability influences their expectation about the person’s ability to form beliefs. Infants were first administered a search task in which they observed an experimenter show excitement while looking inside a box that either contained a toy (reliable looker condition) or was empty (unreliable looker condition). The infants were then administered a true belief task in which they watched as the same experimenter hid a toy in 1 of 2 locations. In the test trial, the infants witnessed the experimenter search for the toy in a location that was consistent or inconsistent with her belief about the toy’s location. Results for the true belief task indicated that only the infants in the reliable looker condition looked longer at the incongruent than at the congruent search behavior. These findings are consistent with evidence suggesting that infants encode the identity of agents based on past reliability and implicitly attribute beliefs to others during the 2nd year of life. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive and motor deficits in the performance of an object retrieval task with a barrier-detour in monkeys (Cercopithecus aethiops sabaeus) treated with MPTP: Long-term performance and effect of transparency of the barrier.

Studied 6 monkeys' performance on an object retrieval task to assess neural deficits produced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The task required retrieval of a reward from a transparent box open on 1 side and fastened to a tray in the cage. Orientation of open side, position on tray, and position of banana in box were manipulated to vary difficulty. Ss treated with MPTP were compared with 5 saline-treated controls. MPTP Ss had no gross neurological deficits but did have motor and cognitive deficits during task acquisition 8–22 mo after treatment (J. R. Taylor et al, in press). Task performance was examined for 3 mo after it had been learned. MPTP Ss reached at the barrier significantly more than controls and were less successful at retrieval on 1st reach than controls. Although MPTP Ss took longer to initiate the reach and had more motor problems, MPTP Ss were as likely as controls to retrieve the reward in the end. These deficits were stable throughout testing. An opaque but otherwise identical box was used randomly on some trials. MPTP Ss decreased barrier reaches to control levels on trials with the opaque box, whereas motor problems increased. The task detected performance deficits similar to those found in Parkinson's disease. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The onset of representation and entry into Stage 6 of object permanence development.

Attempted to determine whether infants' performance in 2 search tasks was related to their entry into Stage 6 of object permanence development and thereby to test Piaget's claim that only Stage 6 infants possess the capacity for representation. Ss were 85 10-mo-olds. In these tasks, Ss found either the same toy as or a different toy than they had seen hidden (Task 1) or which their mother had told them to find (Task 2). Two dependent measures used in each task were the Ss' continuation of search and their smiling in reaction to finding a toy. In both longitudinal and cross-sectional designs, Ss in early Stage 6 (i.e., solving a single invisible displacement), but not in Stage 5, responded differentially on these measures. The early Stage 6 Ss continued to search more frequently in reaction to finding the toy in the different than same condition, while they smiled longer and earlier in the same than different condition. Results suggest that infants begin to demonstrate some representative capacity during early Stage 6 of object permanence development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retarded object permanence development in methylmercury exposed Macaca fascicularis infants.

Mothers of 12 full-term, normal birth-weight Macaques (Macaca fascicularis) received methylmercury (MeHg) hydroxide orally in apple juice at 50 μg/kg/day for 4 mo to 2 yrs before conception and at individual doses during pregnancy. Mothers of 12 control infants received apple juice without MeHg. Infants were separated from their mothers on delivery and were laboratory reared. Beginning at 14 days of age, infants were tested for object permanence development using a plain reach task and hiding tasks. Results indicate that the performance of the MeHg-exposed infants on the full hiding task was significantly retarded compared with controls. On average, exposed infants required nearly twice as many sessions and were over 1 mo older than control infants when they would retrieve the fully hidden object. Although not all of the MeHg-exposed infants who exhibited retarded object permanence development showed signs of attentional problems, it is suggested that for some infants, these attentional problems may be an early precursor to later cognitive deficits. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of hiding places and the transition to Stage IV performance in object permanence tasks.

Three studies with 53 6–10 mo old infants tested T. G. Bower's (1974, 1975) conjecture that infants' Stage IV object permanence difficulties can be attributed to their interpretation of occlusion as replacement. In Study 1, several types of barriers (upright screen, inverted cup, upright box, cloth) were used in a standard object permanence procedure. Results partially support an order of difficulty predicted by Bower's explanation. Ss were consistently delayed, however, in retrieving objects from inside the upright box. Study 2 investigated the role of previous training and found no effect. When barrier size was varied in Study 3, only the smaller box had the lower successful retrieval rate. Measures of looking and mode of manual search indicated that Ss looked appropriately but did not know how to search inside the small box. An argument is made for standardizing barriers and for measuring looking and searching patterns as well as successful retrieval in object permanence studies. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cellular distribution of calbindin D28K mRNAs in the adult mouse brain

Catching a moving object requires the ability to predict the future trajectory of the object. To test whether infants can use visual information predictively, reaching for a toy moving at different speeds was investigated in six infants around 11 months of age. The toy was occluded from view by a screen during the last part of its approach. Gaze arrived at the exit side of the screen and the hand started to move forward before the toy had disappeared behind the occluder; these actions were prospectively geared to certain times before the toy would reappear. In addition, hand-movement duration was found to be related to the time of reappearance of the toy--the information used to regulate duration of hand movement being picked up before the toy disappeared behind the occluder. In a longitudinal experiment, the development of predictive reaching was investigated in two infants between the ages of 20 and 48 weeks. At all ages studied, gaze anticipated the reappearance of the moving toy. However, anticipation with hand movement of the disappearance of the toy and the ability to gear actions prospectively to the time (instead of distance) the toy was away from certain points on the track developed relatively late and marked the transition to successfully catching faster-moving toys.     

Why do infants make A not B errors in a search task, yet show memory for the location of hidden objects in a nonsearch task?

In 4 experiments, infants aged 8 to 12 months were tested on A not B search tasks, and nonsearch A not B tasks following the violation-of-expectation paradigm. A 1-location task and 2 control tasks were also conducted. In the nonsearch tasks, a toy was hidden in A, moved to B, and retrieved after a delay from either A (impossible) or B (possible). Results showed significantly longer looking times at impossible events, indicating some memory for where the object was hidden and an expectation of where it should be found. This effect occurred at delays at which infants made the A not B error when searching, and at a longer delay of 15 s. The results showed clearly that infants have some memory for the object's location, even at delays at which they search at the incorrect location. Discussion centers on how these results are accounted for within explanations of the A not B error. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What comes first? How selective attentional processes regulate the activation of a motor routine in a manual search task.

An intriguing error has been observed in toddlers presented with a 3-location search task involving invisible displacements of an object, namely, the C-not-B task. In 3 experiments, the authors investigated the dynamics of the attentional focus process that is suspected to be involved in this task. In Experiment 1, 2.5-year-old children were tested on a new adaptation of the C-not-B task in which the opening of the experimenter's hand between cloths provided visual information about the correct localization of the toy. Children still emitted a strong response bias toward the last hiding place. In Experiment 2, 2.5-year-old children were tested on a new version of the task that was designed to investigate the role of the central location in the task. This 2nd experiment demonstrated that changing the hand's movement from A to C to B did not enable children to succeed in the task. In Experiment 3, 2.5-year-old children were tested in a situation that is analogous to the C-not-B with open hands task except for the fact that the experimenter dropped the toy under the 1st cloth in the path. Toddlers succeeded when the toy was hidden at Location A but not when it was hidden at Location B. Data indicate that attentional focus on the experimenter's hand motion is contingent on whether that stimulus is critical to performing the task. We argue that these findings provide a potential mechanism through which motor routines can be regulated in accordance with strategic intentions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Constraints on problem solving and inhibition: Object retrieval in cotton-top tamarins (Saguinus oedipus oedipus).

Problem solving relies on a combination of the capacity to generate appropriate solutions and the ability to inhibit prepotent inappropriate responses. Often, problems with the latter prevent some animals from performing well on problem-solving tasks. The authors used the object retrieval task to examine inhibition in cotton-top tamarins (Saguinus oedipus oedipus). They found that, like human infants, tamarins had difficulty retrieving a reward from inside a transparent box when the opening was on the side because they could not inhibit the tendency to reach straight into the solid face of the box. However, subjects trained with an opaque box prior to testing on the transparent box performed perfectly. These results suggest that although the inability to inhibit prepotent biases prevents individuals from acquiring an initial strategy, sufficient training on an effective strategy may allow animals to overcome their initial difficulties with tasks requiring inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Understanding attention: 12- and 18-month-olds know what is new for other persons.

Infants at 12 and 18 months of age played with 2 adults and 2 new toys. For a 3rd toy, however, 1 of the adults left the room while the child and the other adult played with it. This adult then returned, looked at all 3 toys aligned on a tray, showed great excitement ("Wow! Cool!"), and then asked, "Can you give it to me?" To retrieve the toy the adult wanted, infants had to (a) know that people attend to and get excited about new things and (b) identify what was new for the adult even though it was not new for them. Infants at both ages did this successfully, lending support to the hypothesis that 1-year-old infants possess a genuine understanding of other persons as intentional and attentional agents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Priming 4.5-month-old infants to use height information by enhancing retrieval.

How do infants select and use information that is relevant to the task at hand? Infants treat events that involve different spatial relations as distinct, and their selection and use of object information depends on the type of event they encounter. For example, 4.5-month-olds consider information about object height in occlusion events, but infants typically fail to do so in containment events until they reach the age of 7.5 months. However, after seeing a prime involving occlusion, 4.5-month-olds became sensitive to height information in a containment event (Experiment 1). The enhancement lasted over a brief delay (Experiment 2) and persisted even longer when infants were shown an additional occlusion prime but not an object prime (Experiment 3). Together, these findings reveal remarkable flexibility in visual representations of young infants and show that their use of information can be facilitated not by strengthening object representations per se but by strengthening their tendency to retrieve available information in the representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of cue configuration geometry for spatial orientation in human infants (Homo sapiens).

Research with both rats and human infants has found that after inertial disorientation, the geometry of an enclosed environment is used in preference over distinctive featural information during goal localization. Infants (Homo sapiens, 18–24 months) were presented with a toy search task involving inertial disorientation in 1 of 2 conditions. In the identical condition, 4 identical hiding boxes in a rectangular formation were set within a circular enclosure. In the distinctive condition, 4 distinctive hiding boxes were used. Infants searched the goal box and its rotational equivalent significantly more than would be expected by chance in the identical condition, showing that they were sensitive to the geometric configuration of the array of boxes. Unlike the results of studies using a rectangular enclosure, however, in the distinctive condition, infants searched at the correct location significantly more than at other locations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Le changement représentational affectif chez les enfants d'age préscolaire.

Presents a series of experiments focused on preschool children's ability to understand representational change in both the affective and physical domains. In Exp 1, 24 5-yr-olds were asked if they would rather play with a box of crayons or a box of cards. They were also asked how they felt once the box had been opened and they found paper instead of their chosen toy and what was really in the box. Results showed that children correctly answered the questions about past representation in both domains. However, they had difficulty in reporting their present negative emotional state. In Exp 2, 48 5-yr-olds were administered an affective representational task change task in which they first had to rank objects. They were told that they that would receive the most attractive toy but instead were given the least attractive toy (positive-negative emotional sequence) or vice versa (negative-positive emotional sequence). Results indicate that children correctly answered the representational change questions in the negative-positive sequence but not in the positive-negative sequence. Finally, in Exp 3, 24 4-yr-olds failed to perform both the representational change task from Exp 2 and the task from Exp 1. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Young children associate novel words with complex objects rather than salient parts.

How do children learn associations between novel words and complex perceptual displays? Using a visual preference procedure, the authors tested 12- and 19-month-olds to see whether the infants would associate a novel word with a complex 2-part object or with either of that object's parts, both of which were potentially objects in their own right and 1 of which was highly salient to infants. At both ages, children's visual fixation times during test were greater to the entire complex object than to the salient part (Experiment 1) or to the less salient part (Experiment 2)--when the original label was requested. Looking times to the objects were equal if a new label was requested or if neutral audio was used during training (Experiment 3). Thus, from 12 months of age, infants associate words with whole objects, even those that could potentially be construed as 2 separate objects and even if 1 of the parts is salient. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Successful performance by monkeys with lesions of the hippocampal formation on AB? and object retrieval, two tasks that mark developmental changes in human infants.

In this study, (a) what determines success or failure in the AB? and object retrieval tasks and (b) the relation between brain maturation and cognitive development as indexed by these tasks were examined. Intact cynomolgus monkeys and those with bilateral lesions of the hippocampal formation (H+) were tested. Although H+ monkeys exhibited impaired memory by performing poorly on the delayed nonmatching to sample task, they performed well on AB? at delays of 2–25 s. Performance declined as delays increased to 30 s, but H+ monkeys never showed the AB? error pattern. On object retrieval, H+ monkeys succeeded quickly and efficiently, even when required to detour to the box opening. This research demonstrates that memory impairment alone cannot account for deficits on AB? or on object retrieval and strengthens the conclusion (A. Diamond, 1988) that improved performance on AB? and object retrieval during infancy reflects maturation of dorsolateral prefrontal cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infants' use of attentional cues to identify the referent of another person's emotional expression

This study explored 14- and 18-month-old infants' ability to identify the target of an emotional display. In the visual task, infants were presented with 2 boxes. Each box contained an object that could be identified by opening the box lid and looking inside. In the tactile task, the objects had to be pulled out of the boxes before they could be seen. An experimenter expressed happiness as she looked or put her hand inside one box, and disgust as she repeated this action with the other box. Infants were then allowed to explore the boxes. Infants touched both boxes but preferred to search for the happy object. Thus, regardless of age or task, infants identified the target of each emotional display as something inside a box and not the box itself. Infants appeared to use the experimenter's attentional cues (gaze and action) to interpret her emotional signals and behaved as if they understood that she was communicating about the objects.     

Grade Level and Task Difficulty in Learning by Discovery and Verbal Reception Methods.

The present study compared the acquisition, retention, and transfer performance of subjects taught by the verbal reception and discovery methods. First-, third-, and sixth-grade subjects acquired a simple or complex conceptual rule by either the verbal reception or discovery method. The results indicated that discovery subjects took significantly longer than verbal reception subjects to reach the original learning criterion. Verbal reception subjects generally demonstrated performance which was superior to discovery subjects on all measures of retention and transfer. The level of task difficulty interacted with the method of instruction so that increases in task difficulty led to an increase in the differential effectiveness of the two teaching methods. Differences in experience with the two instructional methods was proposed as one of the variables contributing to the above results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The dawning of a past: The emergence of long-term explicit memory in infancy.

The ability to recall information about the past is thought to emerge in the 2nd half of the 1st year of life. Although there is evidence from both cognitive neuroscience and behavioral psychology to support this hypothesis, there is little longitudinal evidence with which the question can be addressed. Infants' memory abilities were tested between the ages of 9 and 16 months using elicited and deferred imitation. Infants' memory for events was tested after delays ranging from 1 to 6 months. The results suggest that at 9 months of age, infants are able to store and retrieve representations over delays of as many as 4 weeks but not over long delays. In contrast, 10-month-olds have at their disposal a system that allows encoding and retrieval of event representations over delays of up to 6 months. These results support the idea that the system that underlies long-term ordered recall emerges near the end of the 1st year of life. (PsycINFO Database Record (c) 2010 APA, all rights reserved)